TC 1818a Control Module Operating Guide SWM-015.5
This guide is intended solely for use by owners of Thermon HeatChek TM heat tracing control and monitoring units. This manual describes operation for TC 1818 controllers with fi rmware released in 2010. Earlier versions of fi rmware may not include all features described in this manual. This manual is considered proprietary and is protected by copyright. Use by others without expressed written consent of Thermon is strictly prohibited. Thermon 1999, 2005, 2008, 2010 HeatChek and TraceView are tradenames of Thermon Manufacturing Company.
TC 1818a Control Module INDEX The TC 1818a Module... 4 TC 1818a Module Specifications... 8 Typical HeatChek Control and Monitoring Units... 9 Programming The TC 1818a... 10 The TC 1818a in Operation... 37 Configuring the TC 1818a for Ambient Sensing or Dual RTD Control... 51 Programming and Operating the TC 1818a in an Ambient Sensing Control Mode... 55 Programming and Operating the TC 1818a with Dual Input RTDs for a Single Control Circuit... 60 Typical Control Applications... 62 Communications... 71 Options and Accessories... 72 Help... 73 Attachment A: TC 1818a Command Flowchart
TC 1818a Control Module THE TC 1818a MODULE The TC 1818a is a microprocessor-based temperature control and monitoring module developed specifi cally for heat tracing. The multi-circuit module can provide heat tracing control, digital information display and alarms for high temperature, low temperature, high current, low current, high ground leakage current, circuit fault, and damaged temperature sensor for up to eighteen heat tracing circuits. Resettable minimum and maximum temperatures seen are retained for display on demand. The TC 1818a module operates independently and can also be connected to a data highway for remote systems communication functions through a personal computer or a distributed control system (DCS). 4
Operating Guide DATA DISPLAY The TC 1818a module utilizes a backlit Liquid Crystal Display (LCD) for reporting temperatures, currents, and other operating parameters. Alarm LED's in conjunction with the information display indicate high temperature, low temperature, high heater current, low heater current, high ground leakage, sensor fault, and circuit fault alarm status. Additional LED s indicate status of power to the TC 1818a, power to the heat tracing circuits, CPU status, and the general controller alarm status. DATA ENTRY The TC 1818a has a 16 key "tactile feel" membrane switch keypad which provides for modifi cation (with security key access) of all control parameters as well as permits inquiries into the status of any circuit being controlled or monitored. ALARM RELAY The TC 1818a module is provided with three independent normally open, close on alarm, solid state alarm relay contacts, rated 1A at 120/240 VAC. The fi rst of these relays activates in the event of any alarm. The second relay contact activates when any "trip" designated alarms occur. Inverse mode operation on either of these alarms is also confi gurable. The third alarm contact provides information regarding the status of internal module CPU diagnostics. CONTROL RELAY The TC 1818a module can be confi gured with up to eighteen DC outputs each having a sink current capability of 100 ma @ 24 VDC for switching up to 18 solid state power relays. MODULE POWER The TC 1818a module is convertible from 120 VAC to 208/ to 240 VAC instrument voltage (50 to 60 HZ) from a slide selector switch. COMMUNICATIONS Each TC 1818a module is provided with an RS-485 communications port for connection through a two wire twisted shielded pair network into a PC. The Modbus ASCII or RTU protocol at 9600 baud rate communications streams may also be interfaced into the distributed control system (DCS). INPUT/OUTPUT MODULE INTERLINK Each TC 1818a can be interlinked with up to three six point sensor input modules and three six circuit power output modules through ribbon cable connections. 5
TC 1818a Control Module The TC 1818a is designed to be an integral part of a HeatChek TM control and monitoring unit. Each unit typically includes one or more TC 1818a modules, power output modules, and sensor input modules, all inter-connecting wiring and ribbon cables, and an electrical enclosure suitable for the environment. POWER OUTPUT MODULES Each TC 1818a power output module is confi gured with six solid state power relays. The single switch SSR30 relays utilized are zero crossing solid state with a single cycle surge capacity of 600A and a one second overcurrent capacity of 80A. The dual switch SSR15 relays are zero crossing solid state with a single cycle surge capacity of 500A and a one second overcurrent capacity of 80A. Design current rating limits for these power output modules are determined by the relay type, enclosure size, ambient conditions, and heat sink style (maximum of 30A per single switch relay and 15A for each switch in a dual switch relay). See Table 1 for details. Each power output module is provided complete with input/output terminal blocks for up to six heat tracing circuits, ribbon cable up to 15 ft (4.6 m) in length, connectors for linking to the TC 1818a control module, and a "touch safe" polycarbonate cover mounting assembly. Table 1: Current Rating Maximum Total Heater Current Through Solid State Relays Per Enclosure Enclosure Option Heat Sink Style C 6SSR30C Heat Sink Style C 6SSR15C PS4, SS4 360A 180A PS5, SS5 576A 288A Current ratings are based on outdoor ambients of 104 o F (40 o C) with solar loading. Contact the factory for ratings at higher ambient conditions or for ratings in larger enclosure sizes. The 6SSR30C includes six single switch solid state relays suitable for controlling up to 30 amperes per switch. The 6SSR15C includes six dual switch solid state relays suitable for controlling up to 15 amperes per switch. 6
Operating Guide CONTROL AND MONITORING UNIT A HeatChek control and monitoring unit utilizing the TC 1818a module, solid state relay power output modules, sensor input modules, and a NEMA 4 or 4X enclosure is approved/certifi ed for use in Class I, Division 2 Hazardous (classifi ed) as well as Ordinary (non-classifi ed) Locations. These units include the following warning markings: CAUTION! CIRCUITS MAY BE ENERGIZED This marking intends that the user must disconnect all power sources to the panel prior to servicing. This marking indicates a location that must be grounded in accordance with local and national requirements. 7
TC 1818a Control Module TC 1818A MODULE SPECIFICATIONS The TC 1818a module has the general specifi cations as detailed below: Control and Monitoring Capacity: Eighteen resistive heat tracing circuits up to 30 amps per circuit (depending on switch type) Module Supply Voltage: Operating Frequency: Power Consumption: 110-120 VAC or 208-240 VAC 50 to 60 Hz Nominal 40 watts per TC 1818a module Module Operating Ambient: -40 o F to +140 o F (-40 o C to +60 o C) Maximum Storage Ambient: 158 o F (70 o C) Data Retention: Power Clamp Function: Non volatile EEPROM Programmable for power levels from 20 to 100% maximum power Input: Up to eighteen 3 wire 100 ohms @ 32 o F (0 o C) platinum RTD's Temperature Range (Control): Control: -40 o F to 932 o F (-40 o C to 500 o C) with programmable control band in increments of one degree On-Off, On-Off with Softstart, Proportional, Proportional Self-Adjust Module Dimensions: 4-1/2" x 19" x 7-1/2" (114 mm x 482 mm x 191 mm) Operating Current Alarm Ground Leakage Alarm/Trip: Self-Test Frequency: High: 1.0 to 30.0 A Low: 0.0 to 30.0 A 30 to 150 ma Programmable from 2 to 99 hours 8
Operating Guide TYPICAL HEATCHEK CONTROL AND MONITORING UNITS The TC 1818a is modular in construction and can be confi gured in a variety of HeatChek control and monitoring units. INFORMATION Additional design selection and engineering information may be found in Form T-1008-E. Specifi c wiring and equipment arrangement details are usually provided in drawings included within the HeatChek control and monitoring unit at time of shipment. 9
TC 1818a Control Module PROGRAMMING THE TC 1818A MODULE ACCESSING THE PROGRAM MODE Turn the key to the vertical position and then press the PROG key to enter the programming mode. PROG The TC 1818a will then display the following message: PROGRAM MODE ENABLED SELECT FUNCTION KEY Then select the desired function key (e.g. MAINTAIN TEMP). MAINTAIN TEMP If the function key is not a global function (e.g. CONFIG, DATA HWY, etc.) then the following message appears. PROGRAM CIRCUIT=1 Select the desired circuit by pressing the UP or DOWN arrow keys and then pressing the ENTER key. In order to set all circuits to a common value, press the UP arrow key until "ALL THE SAME VALUE" appears. PROGRAM = ALL THE SAME VALUE Press ENTER to globally set a control or operating parameter. 10
Operating Guide MAINTAIN TEMPERATURE (PROGRAM MODE) The following is a typical message which might appear: MAINTAIN TEMP=104 F NEW VALUE=104 F Momentarily pressing the UP or DOWN arrow keys will cause the NEW VALUE to change by 1 degree increments. Holding the key down results in a 10 degree incremental change. If an upper or lower limit is reached, a MAX or MIN message will appear on the second line. This indicates that either the absolute maximum or minimum value has been reached or that the value has reached an alarm value. MAINTAIN TEMP=104 F NEW VALUE=50 F Once the desired temperature value is set, press the ENTER key to save the value. The controller will then exit the programming mode and return to the Scan Mode RETURN TO SCAN MODE 11
TC 1818a Control Module HIGH TEMPERATURE ALARM (PROGRAM MODE) Pressing the HIGH TEMP ALARM function key results in a display message such as the following: HIGH TEMP ALARM HIGH TEMP ALARM=160 F NEW VALUE=160 F The TC 1818a is set to alarm at 160 o F on the current circuit number. Should the control temperature reach 160 o F, the red "ALARM ON" LED on the TC 1818a will begin to fl ash and the "HIGH TEMP" LED will illuminate when the circuit in alarm appears on the INFORMATION DISPLAY. In addition, the alarm relay contact will close (depending on confi guration, inverse action may occur). To change the current value, press the UP or DOWN arrow keys to increase or decrease the current HIGH TEMP ALARM setpoint. HIGH TEMP ALARM=160 F NEW VALUE=120 F 12
Operating Guide Once the desired temperature value is set, press the ENTER key to save the value. Next, the following typical message will appear: 2 HIGH TEMP SEEN=200 F RESET? (Y/N) At some point since this controller was last reset, the temperature has attained 200 F. Press the UP arrow key and ENTER to clear this value and begin anew at the current value. Pressing ENTER or PROG key results in the current value of 200 F being retained. Subsequently, the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 13
TC 1818a Control Module LOW TEMPERATURE ALARM (PROGRAM MODE) Pressing the LOW TEMP ALARM function key results in a display message such as the following: LOW TEMP ALARM LOW TEMP ALARM=50 F NEW VALUE=50 F The TC 1818a is set to alarm at 50 o F on the current circuit number. Should the control temperature drop to 50 o F, the "ALARM ON" LED on the TC 1818a will begin to fl ash and the "LOW TEMP" LED will illuminate when the circuit in alarm appears on the INFORMATION DISPLAY. In addition, the alarm relay contact will close (depending on confi guration, inverse action may occur). To change the present value, press the UP or DOWN arrow keys to increase or decrease the present LOW TEMP ALARM setpoint.once the desired temperature value is set, press the ENTER key to save the value. LOW TEMP ALARM=50 F NEW VALUE=35 F 14
Operating Guide Next, the following typical message will appear: 2 LOW TEMP SEEN=40 F RESET? (Y/N) At some point since this controller was last reset, the control temperature has dropped to 40 F. Pressing the ENTER key results in the present value of 40 F being retained. Press the UP arrow key and ENTER to clear the stored value and begin anew at the current value. Subsequently, the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 15
TC 1818a Control Module HEATER CURRENT (PROGRAM MODE) Pressing the HEATER CURRENT key (when the TC 1818a is confi gured with solid state relays and is set for On-Off with Soft Start, Proportional, or Proportional with Self-Adjust) results in a display message as typically given below: HEATER CURRENT POWER AT MAINT TEMP=22% NEW VALUE=22% In this case, the power clamp function is currently in the active or enabled mode. In this mode, the TC 1818a will (through the zero crossing solid state relay provided) use cycle omission techniques to limit the maximum power available to the heater to the value shown (to some value less than the heater would ordinarily provide) at the temperature control setpoint. For more details, refer to pages 27 and 28. Pressing the ENTER key will retain the current mode of operation. Pressing the UP or DOWN arrow key and pressing ENTER will result in the altering of the power percentage and hence result in the limiting of heater power when "ON" at the temperature control setpoint. 16
Operating Guide The TC 1818a will now return to Scan Mode. RETURN TO SCAN MODE The TC 1818a is provided with a built-in "Soft Start" power up feature when confi gured in the On-Off with Soft Start, Proportional, or Proportional Self-Adjust modes. This feature will utilize cycle omission techniques to ramp up to maximum allowable heater power in a span of approximately 5.5 minutes. This ramp up feature is designed to specifi cally address a) cold start power surges associated with self limiting and power limiting heaters, and b) minimize overshoot which may sometimes be present when utilizing high output heaters in low heat loss applications. Should the TC 1818a be confi gured in the On-Off mode, no programming functions such as Power Clamping are available. In addition, no "Soft Start" control functions will be active. 17
TC 1818a Control Module GROUND CURRENT (PROGRAM MODE) Pressing the GROUND CURRENT function key results in a display message such as the following: GROUND CURRENT GROUND CURRENT ALARM=40mA NEW VALUE=40mA The TC 1818a is set to alarm at heater and associated wiring ground leakage current of 40mA on the chosen circuit number. Should the ground leakage value reach 40mA, the "ALARM ON" LED on the TC 1818a will begin to fl ash and the "GROUND CURRENT" LED will illuminate when the circuit in alarm appears on the INFORMATION DISPLAY. In addition, the alarm relay contact will close (depending on confi guration, inverse action may occur). To change the value, press the UP or DOWN arrow keys to increase or decrease the GROUND CURRENT ALARM setpoint. GROUND CURRENT ALARM=40mA NEW VALUE=30mA Once the desired new value is set, press the ENTER key to save the value. Subsequently, the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 18
Operating Guide HIGH CURRENT ALARM (PROGRAM MODE) Pressing the HIGH CURRENT ALARM function key results in a display message such as the following: HIGH CURRENT ALARM HIGH CURRENT ALARM=20.0A NEW VALUE=20.0A The TC 1818a is set to alarm at heater current levels above 20 Amperes on the present circuit number. Should the heater current reach 20A, the "ALARM ON" LED on the TC 1818a will begin to fl ash and the "HIGH CURRENT" LED will illuminate when the circuit in alarm appears on the INFORMATION DISPLAY. In addition, the alarm relay contact will close (depending on confi guration, inverse action may occur). To change the value, press the UP or DOWN arrow keys to increase or decrease the HIGH CURRENT ALARM setpoint. HIGH CURRENT ALARM=20.0A NEW VALUE=25.0A Once the desired new value is set, press the ENTER key to save the value. Subsequently, the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 19
TC 1818a Control Module LOW CURRENT ALARM (PROGRAM MODE) Pressing the LOW CURRENT ALARM function key results in a display message such as the following: LOW CURRENT ALARM LOW CURRENT ALARM=1.0A NEW VALUE=1.0A The TC 1818a is set to alarm at heater current levels below 1 Ampere. Should the heater current drop to 1A, the "ALARM ON" LED on the TC 1818a will begin to fl ash and the "LOW CURRENT" LED will illuminate when the circuit in alarm appears on the INFORMATION DISPLAY. In addition, the alarm relay contact will close (depending on confi guration, inverse action may occur). To change the value, press the UP or DOWN arrow keys to increase or decrease the LOW CURRENT ALARM setpoint. LOW CURRENT ALARM=1.0A NEW VALUE=2.0A Once the desired new value is set, press the ENTER key to save the value. Subsequently, the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 20
Operating Guide CONFIG (PROGRAM MODE) The CONFIG key provides access to setting all global control parameters on the TC 1818a. Pressing the CONFIG key results in the following display prompt: RTD FAULT TURNS CKT ON CHANGE? (Y/N) A "Yes" entry will result in an "Open" relay condition in the event of a RTD sensor failure. Press the UP arrow key for "Yes" or DOWN arrow key for "No." Then press the ENTER key to save. A "No" entry will result in a "Closed" relay condition in the event of a RTD sensor failure. Subsequently, the TC 1818a follows with the below message on the information display: GROUND CURRENT TRIP OFF CHANGE? (Y/N) The TC 1818a is currently set to NOT trip the heater circuits if a high ground leakage condition occurs, but rather will only "fl ash" the "ALARM ON" LED and close the standard alarm relay (open in inverse operation). To retain the present mode of GROUND CURRENT TRIP operation, press the ENTER key. Pressing the UP arrow key and ENTER will result in the TC 1818a setting being changed to GROUND CURRENT TRIP ON. 21
TC 1818a Control Module The TC 1818a will then prompt for the preferred HIGH CURRENT trip setting. HIGH CURRENT TRIP OFF CHANGE? (Y/N) The TC 1818a is currently set to NOT trip the heater circuits if a high heater current alarm condition occurs, but rather will only "fl ash" the "ALARM ON" LED and close the standard alarm relay (open in inverse operation). To retain the present mode of HIGH CURRENT ALARM operation, press the ENTER key. Pressing the UP arrow key and ENTER will result in the TC 1818a setting being changed to HIGH CURRENT TRIP ON. Once set in this manner, the heater circuits will trip (open heater relay contacts) should a heater current alarm condition occur. The TC 1818a will now require that the operator 1) press the ACKNOWLEDGE key, 2) and the high current alarm condition be cleared prior to automatic control being restored. The TC 1818a next prompts for the HIGH TEMP ALARM trip setting. HIGH TEMP TRIP OFF CHANGE? (Y/N) 22
Operating Guide The TC 1818a is currently set to NOT trip the heater circuits if a high temperature alarm condition is reached, but rather to only "fl ash" the "ALARM ON" LED and close the standard alarm relay (open in inverse operation). To retain the present mode of HIGH TEMP ALARM operation, press the ENTER key. Pressing the UP arrow key and ENTER will result in the TC 1818a setting being changed to HIGH TEMP TRIP ON. Once set in this manner, the heater circuits will trip (open heater relay contacts) should a high temperature alarm condition occur. The TC 1818a will now require that the operator 1) press the ACKNOWLEDGE key, 2) and the high current alarm condition be cleared prior to automatic control being restored. The TC 1818a is provided with On-Off, On-Off with Soft Start, Proportional, and Proportional with Self-Adjust control options. The information display next prompts for the type of control to be selected. In the ON-OFF control mode, the heater circuit will turn on and off within the programmed control band value. CONTROL = ON/OFF CHANGE? (Y/N) Press the DOWN arrow and ENTER key to accept this control type. Otherwise, to change the control type, press the UP arrow key and the ENTER key. The ON-OFF with SOFT-START option allows the circuit to be gradually powered up by zero crossing cycle omission over a span of approximately 5.5 minutes. Thereafter, the heater circuit will turn on and off within the programmed control band value. CONTROL = SOFT/START CHANGE? (Y/N) 23
TC 1818a Control Module To retain the present setting, press the ENTER key. To change the control type, press the UP arrow key and the ENTER key. The PROPORTIONAL option will now control the heater within the programmed control band using a proportional algorithm. This algorithm will adjust the power at maintain from 20% - 100% (or programed value). CONTROL = PROPORTIONAL CHANGE? (Y/N) To retain the present setting, press the ENTER key. To change the control type, press the UP arrow key and the ENTER key. CONTROL = SELF ADJUST CHANGE? (Y/N) With the SELF-ADJUST feature, the TC 1818a will measure the inherent system error and will automatically adjust the proportional control parameters to decrease the deviation from setpoint to a minimal value. To retain the present setting, press the ENTER key. To change the control type, press the UP arrow key and the ENTER key. Note the SELF-ADJUST control option is only available in the SINGLE RTD controller confi guration. 24
Operating Guide The TC 1818a offers the option of setting the standard alarm relay switch to be "Closed on Alarm" or "Open on Alarm." The information display next prompts for alarm preferences. STD ALARM CLOSED ON ALARM CHANGE? (Y/N) Press the ENTER key to retain the current setting. Press the UP arrow key and the ENTER key to change the alarm switch action. The TC 1818a also offers the option of setting the second TRIP alarm relay switch to be "Closed on Alarm" or "Open on Alarm." The information display next prompts for alarm preferences. TRIP ALARM CLOSED ON ALARM CHANGE? (Y/N) 25
TC 1818a Control Module Press the ENTER key to retain the current setting. Press the UP arrow key and the ENTER key to change the alarm switch action. The TC 1818a is standardly provided with a SELF TEST function which turns each of the heater circuits "On" and "Off" and looks for the appropriate changes in the relay heater current. During the heater "On" state, the TC 1818a also checks for the presence of both "LOW CURRENT" alarms and "GROUND CURRENT" alarms. The TC 1818a prompts for the desired settings for the "SELF TEST." AUTO SELF TEST = OFF NEW VALUE = OFF MIN. The SELF TEST function is currently disabled. Press the ENTER key to retain this setting. Press the UP arrow key and the ENTER key to change to an automatic SELF TEST interval from 2 to 99 hours. Subsequently the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 26
Operating Guide CONTROL BAND (PROGRAM MODE) Pressing the CONTROL BAND key results in the following display prompt: CONTROL BAND=3 o F NEW VALUE=3 o F If confi gured in the "On-Off" or "Soft Start" control mode, the TC 1818a will turn on the heater at the maintain temperature setpoint and will turn off at 3 o F above this value. ON-OFF CONTROL WITH 100% POWER Maintain Temp 100% 0% Heater Power Control Band If programmed to operate in the "Proportional Mode", and the "Power at Maintain Temperature" is set at 100%, the TC 1818a will operate at 100% power below the maintain temperature setpoint and will ramp down in power within the control band and subsequently turn off when above the maintenance temperature plus control band. PROPORTIONAL WITH 100% POWER Maintain Temp 100% 20% 0% Heater Power Control Band 27
TC 1818a Control Module If the "Power at Maintain Temperature" has been programmed to some other value (for example, 62%), the TC 1818a will operate at that power level value at the maintenance temperature and the control band range will adjust as shown below. PROPORTIONAL WITH 62% POWER 100% Maintain Temp Control Band 62% 20% 0% Heater Power Adjusted Control Band When confi gured in the "Proportional with Self-Adjust" mode, the TC 1818a will initially operate in the "Proportional Mode" and will subsequently begin to automatically adjust the slope of the power ramp down. The "Power at Maintain Temperature" will decrease until power output matches the demand. PROPORTIONAL WITH SELF-ADJUST Maintain Temp 100% 55% Steady State 0% Heater Power Control Band 28
Operating Guide To retain present control band setting, press the ENTER key. Press the UP or DOWN arrow key to increase or decrease the control band and press ENTER to save the new value. Subsequently, the TC 1818a returns to the Scan Mode. RETURN TO SCAN MODE 29
TC 1818a Control Module HEATER ENABLE (PROGRAM MODE) The TC 1818a can be factory confi gured for operation with a variety of pipe sensing, ambient sensing, and RTD assignment confi gurations. When programming the HEATER ENABLE settings in one of these control confi gurations, the following alternate prompt window messages may appear. For the controller confi guration SINGLE RTD INPUTS, the following message will appear Prompt Window Message ENABLED CHANGE? (Y/N) DISABLED CHANGE? (Y/N) FORCE HEATER ON? (Y/N) Explanation The ENABLED prompt will appear on all process sensing circuits. These circuits will turn on when the TC 1818a senses a process temperature below the maintain temperature setpoint. The DISABLED prompt allows the option of disabling this control circuit for service work. The FORCE HEATER ON prompt allows the option of temporarily turning on the heater circuit for diagnostic purposes. For the controller confi guration 1 AMB / SINGLE RTD INPUTS, the following message will appear. Prompt Window Message ENABLED (AMBIENT SENSE) CHANGE? (Y/N) ENABLED (PIPE SENSE) CHANGE? (Y/N) DISABLED CHANGE? (Y/N) FORCE HEATER ON? (Y/N) Explanation The ENABLED (AMBIENT SENSE) prompt will appear for all ambient sensed heater circuits. These heater circuits will turn on when the TC 1818a senses an ambient temperature on Heater Circuit 1 which is below the maintain temperature setpoint. Other circuits may appear as ENABLED (PIPE SENSE). In that case, these heater circuits will turn on when the TC 1818a senses a pipe or heated surface temperature which is below the maintain temperature setpoint. In this controller confi guration, CIRCUIT 1 must be set as AMBIENT SENSE. The DISABLED prompt allows the option of disabling this control circuit for service work. The FORCE HEATER ON prompt allows the option of temporarily turning on the heater circuit for diagnostic purposes. 30
Operating Guide For the controller confi guration 2 AMB/ SINGLE RTD INPUTS, the following message will appear. Prompt Window Message ENABLED (AMBIENT SENSE) CHANGE? (Y/N) ENABLED (PIPE SENSE) CHANGE? (Y/N) DISABLED CHANGE? (Y/N) FORCE HEATER ON? (Y/N) Explanation The ENABLED (AMBIENT SENSE) prompt will appear for all ambient sensed heater circuits. These heater circuits will turn on when the TC 1818a senses an ambient temperature on Heater Circuit 1 or 2 which is below the maintain temperature setpoint. Other circuits may appear as ENABLED (PIPE SENSE). In that case, these heater circuits will turn on when the TC 1818a senses a process temperature which is below the maintain temperature setpoint. In this controller confi guration, CIRCUIT 1 and 2 must be set as AMBIENT SENSE. The DISABLED prompt allows the option of disabling this control circuit for service work. The FORCE HEATER ON prompt allows the option of temporarily turning on the heater circuit for diagnostic purposes. For the controller confi guration 1 or 2 RTD INPUTS, the following message will appear. Prompt Window Message ENABLED (ONE RTD) CHANGE? (Y/N) ENABLED (TWO RTD'S) CHANGE? (Y/N) DISABLED CHANGE? (Y/N) FORCE HEATER ON? (Y/N) Explanation These heater circuit prompts appear when using dual RTD input controller confi gurations. In these cases, the heater circuits will turn on when the TC 1818a senses a process temperature (on one or both RTD sensors) which is below the maintain temperature setpoint. The DISABLED prompt allows the option of disabling this control circuit for service work. The FORCE HEATER ON prompt allows the option of temporarily turning on the heater circuit for diagnostic purposes. 31
TC 1818a Control Module For the controller confi guration 1 AMB/ 1 or 2 RTD INPUTS, the following message will appear. Prompt Window Message ENABLED (AMBIENT SENSE) CHANGE? (Y/N) ENABLED (TWO RTD'S) CHANGE? (Y/N) ENABLED (ONE RTD) CHANGE? (Y/N) DISABLED CHANGE? (Y/N) FORCE HEATER ON? (Y/N) Explanation These prompts appear when using dual RTD process sensing as well as ambient sensing circuit controller confi gurations. These heater circuits will turn on when the TC 1818a senses an ambient temperature (based on the value of the RTD reading in Circuit 1) which is below the maintain temperature setpoint. Other circuit prompts may appear as ENABLED (ONE RTD or TWO RTD'S). In these cases, the heater circuits will turn on when the TC 1818a senses a process temperature (on one or both RTD sensors) which is below the maintain temperature setpoint. Except in the case of CIRCUIT 1 which must be AMBIENT SENSE in this factory confi guration, all other circuits may be set as AMBIENT SENSE or ONE or TWO RTDS control. The DISABLED prompt allows the option of disabling this control circuit for service work. The FORCE HEATER ON prompt allows the option of temporarily turning on the heater circuit for diagnostic purposes. For the controller confi guration 2 AMB/ 1 or 2 RTD INPUTS, the following message will appear. Prompt Window Message Explanation ENABLED (AMBIENT SENSED) CHANGE? (Y/N) ENABLED (ONE RTD) CHANGE? (Y/N) ENABLED (TWO RTD) CHANGE? (Y/N) These prompts appear when using dual RTD process sensing as well as ambient sensing circuit controller confi gurations. These heater circuits will turn on when the TC 1818a senses an ambient temperature (based on the lower value of the RTD reading in Circuit 1 and 2) which is below the maintain temperature setpoint. Other circuit prompts may appear as ENABLED (ONE RTD or TWO RTDS). In that case, these heater circuits will turn on when the TC 1818a senses a process temperature (on one or both RTD sensors) which is below the maintain temperature setpoint. Except in the case of CIRCUIT 1 and 2 which must be AMBIENT SENSE in this controller confi guration, all other circuits may be set as AMBIENT SENSE or ONE or TWO RTDS control. 32
Operating Guide Prompt Window Message Explanation DISABLED CHANGE? (Y/N) FORCE HEATER ON? (Y/N) The DISABLED prompt allows the option of disabling this control circuit for service work. The FORCE HEATER ON prompt allows the option of temporarily turning on the heater circuit for diagnostic purposes. Starting programming by pressing the PROG key. PROG Subsequently, press the HEATER ENABLE key. HEATER ENABLE Select the desired circuit by pressing the UP or DOWN arrow keys and then pressing the ENTER key. Depending on the TC 1818a controller confi guration, variations in the prompt message may be seen. PROGRAM CIRCUIT = 1 A prompt message as shown below will then appear. ENABLED CHANGE? (Y/N) This heater circuit is currently enabled and will turn on when the TC 1818a senses a temperature below the maintain temperature setpoint. 33
TC 1818a Control Module If the TC 1818a is set for an ambient control confi guration the following two enable prompt messages will appear. ENABLED (AMBIENT SENSE) CHANGE? (Y/N) Pressing the DOWN arrow key will leave the heater enabled in the ambient sense mode. Press the UP arrow key and the ENTER key. The TC 1818a will now prompt as follows. ENABLED (PIPE SENSE) CHANGE? (Y/N) Pressing the DOWN arrow key and the ENTER key will result in enabling the heater as a pipe sensing circuit. Pressing the UP arrow key will result in the following new prompt. DISABLED CHANGE? (Y/N) Pressing the DOWN arrow key and the ENTER key wil result in disabling the heater circuit and thus result in the removal of external heat from the pipe or heated surface. The TC 1818a will next prompt as follows. FORCE HEATER ON? (Y/N) Press the UP arrow key and the ENTER key to retain this setting. In this operating mode, the heater will remain ON as long as no programmed alarm limits are exceeded. Pressing the DOWN arrow and ENTER key will result in the TC 1818a returning to SCAN MODE. RETURN TO SCAN MODE 34
Operating Guide DATA HIGHWAY (PROGRAM MODE) Pressing the DATA HIGHWAY key results in the following display prompt: DATA HIGHWAY=4 NEW VALUE=4 The TC 1818a is currently identifi ed as address number 4. This unique address allows the data highway communications software to identify the information being sent by the controller with a location and heater circuit number. To retain the present address value, press the ENTER key. Press the UP or DOWN arrow key to increase or decrease the address value and press ENTER to confi rm the new address. The TC 1818a has the capability to choose the Modbus ASCII or the Modbus RTU protocols. MODBUS ASCII CHANGE? Y/N Pres the ENTER key to retain the current Modbus protocol. Press the UP arrow key to change the protocols. Press the ENTER key to confi rm the new settings. 35
TC 1818a Control Module The TC 1818a allows the successive numbering of circuit numbers for a group of modules. As shown below, the TC 1818a prompts for the beginning circuit number for the control module being programmed. 1ST CIRCUIT NUMBER=1 NEW VALUE = 1 MIN. Press the ENTER key to retain the current beginning circuit number. Press the UP arrow key to arrive at the desired starting point and the ENTER key to confi rm the new starting circuit number. The TC 1818a then returns to the Scan Mode. 36
Operating Guide THE TC 1818A IN OPERATION POWER UP (SCAN MODE) On power up, the TC 1818a will display the following two start-up screen messages. THERMON TC 1818a COPYRIGHT 1995-10 18 RTD INPUTS 18 RELAY OUTPUTS This prompt message indicates that this TC 1818a controller has been confi gured to control eighteen heater circuits with eighteen individual RTD inputs. Depending on the TC 1818a controller confi guration, variations in the above message sequence may be seen. Then the TC 1818a will go into Scan Mode. 37
TC 1818a Control Module Once in Scan Mode operation, in the standard factory confi guration the TC 1818a will sequentially indicate the temperature reading along with the maintain temperature. CKT 1 TEMP=51 F MAINTAIN TEMP=50 o F CKT 4 TEMP=51 F MAINTAIN TEMP=50 F CKT 2 TEMP=122 F MAINTAIN TEMP=120 F CKT 5 TEMP=122 F MAINTAIN TEMP=120 F CKT 3 TEMP=605 F MAINTAIN TEMP=600 F CKT 6 TEMP=605 F MAINTAIN TEMP=600 F Upon displaying all temperature information for all confi gured circuits, the TC 1818a will subsequently return to the fi rst circuit and repeat the display sequence. Refer to page 53 for more details on alternate control options and prompt messages. 38
Operating Guide WHEN IN ALARM (SCAN MODE) Un-Acknowledged Alarms When an alarm condition occurs, the "ALARM ON" LED will begin to fl ash, the "ALARM TYPE" LED's will illuminate when the specifi c circuit in alarm appears on the INFORMATION DISPLAY, and the standard alarm relay will close. Acknowledged Alarms To acknowledge an alarm condition, press the ALARM ACK key. The fi rst alarm condition will be indicated in the INFORMATION DISPLAY. Pressing the ALARM ACK key again will acknowledge this alarm. Repeat this sequence to determine the nature of additional alarms. Acknowledged alarms are indicated by the suffi x Ack appearing when the alarm condition is displayed. Acknowledged alarms will continue to be displayed until the alarm condition clears. When all alarms have been acknowledged then the ALARM ON light on the controller will cease fl ashing but will stay ON until all alarm conditions have cleared. Manual Reset If a TRIP option has been set on a circuit, then all alarms for that circuit must be acknowledged before they will clear. When TRIP has been triggered, the alarm for that trip must be acknowledged and the alarm condition must clear before automatic control is restored. Automatic Reset When no TRIP options have been set, the alarms will automatically clear when the alarm condition has cleared. 39
TC 1818a Control Module ACCESSING DATA (DISPLAY MODE) Press the MAINTAIN TEMP key to display the Maintain Temperature for all circuits as typically shown. MAINTAIN TEMP MAINTAIN TEMP CIRCUIT 1=50 F MAINTAIN TEMP CIRCUIT 4=50 F MAINTAIN TEMP CIRCUIT 2=120 F MAINTAIN TEMP CIRCUIT 5=120 F MAINTAIN TEMP CIRCUIT 3=600 F MAINTAIN TEMP CIRCUIT 6=600 F RETURN TO SCAN MODE Press the HEATER CURRENT key to display the Heater Amperage for all enabled circuits as typically shown. HEATER CURRENT HEATER CURRENT CIRCUIT 1=1.0A HEATER CURRENT CIRCUIT 4=1.0A HEATER CURRENT CIRCUIT 2=5.0A HEATER CURRENT CIRCUIT 5=5.0A HEATER CURRENT CIRCUIT 3=20.0A HEATER CURRENT CIRCUIT 6=20.0A RETURN TO SCAN MODE 40
Operating Guide Press the CONFIG key to display the global settings for all trip and control functions, to view the interval between self tests, and to do a manual SELF TEST on the circuits. A typical display sequence is shown. RTD FAULT TURNS CKT OFF GROUND CURRENT TRIP ON HIGH CURRENT TRIP OFF HIGH TEMP TRIP ON CONTROL = ON/OFF STD ALM CLOSED ON ALARM TRIP ALM CLOSED ON ALARM 2 RTD ALARM DEADBAND TEMP = 1 F * * NOTE: This information screen only appears when a circuit is confi gured for dual RTD inputs. AUTO SELF TEST ON INTERVAL 2 HOURS CIRCUIT TEST IN PROGRESS TESTING CIRCUIT #1 CIRCUIT TEST IN PROGRESS TESTING CIRCUIT #4 CIRCUIT TEST IN PROGRESS TESTING CIRCUIT #2 CIRCUIT TEST IN PROGRESS TESTING CIRCUIT #5 CIRCUIT TEST IN PROGRESS TESTING CIRCUIT #3 CIRCUIT TEST IN PROGRESS TESTING CIRCUIT #6 RETURN TO SCAN MODE 41
TC 1818a Control Module Press the CONTROL BAND key to display the control band settings for all circuits as typically shown. CONTROL BAND CONTROL BAND CIRCUIT 1=2 F CONTROL BAND CIRCUIT 4=2 F CONTROL BAND CIRCUIT 2= 3 F CONTROL BAND CIRCUIT 5=3 F CONTROL BAND CIRCUIT 3= 10 F CONTROL BAND CIRCUIT 6=10 F Subsequently, the TC 1818a returns to Scan Mode. RETURN TO SCAN MODE 42
Operating Guide Press the GROUND CURRENT key to display ground leakage current from heater and associated wiring on all circuits as typically shown. GROUND CURRENT GROUND CURRENT CIRCUIT 1=15mA GROUND CURRENT CIRCUIT 4=15mA GROUND CURRENT CIRCUIT 2=5mA GROUND CURRENT CIRCUIT 5=5mA GROUND CURRENT CIRCUIT 3=10mA GROUND CURRENT CIRCUIT 6=10mA Subsequently the Information display will begin displaying the ground leakage alarm/trip settings for each circuit. GROUND CURRENT ALARM CIRCUIT 1=40mA GROUND CURRENT ALARM CIRCUIT 4=40mA GROUND CURRENT ALARM CIRCUIT 2=30mA GROUND CURRENT ALARM CIRCUIT 5=30mA GROUND CURRENT ALARM CIRCUIT 3=50mA GROUND CURRENT ALARM CIRCUIT 6=50mA Upon completion of the display of the ground current alarm/trip values on all circuits, the TC 1818a returns to Scan Mode. RETURN TO SCAN MODE 43
TC 1818a Control Module Press the HEATER ENABLE key to display if the heater status is set as enabled. The heater status can be enabled, disabled, forced on, or tripped. HEATER ENABLE HEATER CIRCUIT 1= ENABLED HEATER CIRCUIT 4 = ENABLED HEATER CIRCUIT 2= ENABLED HEATER CIRCUIT 5 = ENABLED HEATER CIRCUIT 3= ENABLED HEATER CIRCUIT 6 = FORCED ON Refer to page 54 for more details on alternate HEATER ENABLE prompt messages. Subsequently, the TC 1818a returns to Scan Mode. RETURN TO SCAN MODE 44
Operating Guide Press the HIGH TEMP ALARM key to display the High Temperature Alarm Setpoint and Highest Temperature Seen for all circuits as typically shown. HIGH TEMP ALARM HIGH TEMP ALARM CIRCUIT 1=130 F HIGH TEMP ALARM CIRCUIT 4=130 F HIGH TEMP ALARM CIRCUIT 2=20 F HIGH TEMP ALARM CIRCUIT 5=200 F HIGH TEMP ALARM CIRCUIT 3=700 F HIGH TEMP ALARM CIRCUIT 6= 700 F The TC 1818a will then begin to scroll through the highest stored value of temperature for each circuit. HIGH TEMP SEEN CIRCUIT 1=200 F HIGH TEMP SEEN CIRCUIT 4=200 F HIGH TEMP SEEN CIRCUIT 2=300 F HIGH TEMP SEEN CIRCUIT 5=300 F HIGH TEMP SEEN CIRCUIT 3=700 F HIGH TEMP SEEN CIRCUIT 6=700 F Subsequently, the TC 1818a returns to Scan Mode. RETURN TO SCAN MODE 45
TC 1818a Control Module Press the HIGH CURRENT alarm key to display the High Heater Current Alarm setpoint as typically shown. HIGH CURRENT ALARM HIGH CURRENT ALARM CIRCUIT 1=5.0A HIGH CURRENT ALARM CIRCUIT 4=5.0A HIGH CURRENT ALARM CIRCUIT 2= 10A HIGH CURRENT ALARM CIRCUIT 5=10A HIGH CURRENT ALARM CIRCUIT 3=30A HIGH CURRENT ALARM CIRCUIT 6=30A The TC 1818a then returns to Scan Mode. RETURN TO SCAN MODE Press the DATA HWY key to display the Data Highway address setting for the module and check the data highway communication status (respectively). DATA HWY DATA HIGHWAY ADDRESS=18 COMM STATUS=IN A "COMM STATUS" of IN or OUT denotes direction of the message transmittals (the absence of IN or OUT indicates that data highway communications link has not been established). Subsequently, the TC 1818a then returns to Scan Mode. RETURN TO SCAN MODE 46
Operating Guide Press the LOW TEMP ALARM key to display the Low Temperature Alarm Setpoint and Lowest Temperature Seen for all circuits as typically shown. LOW TEMP ALARM LOW TEMP ALARM CIRCUIT 1=35 F LOW TEMP ALARM CIRCUIT 4=35 F LOW TEMP ALARM CIRCUIT 2=75 F LOW TEMP ALARM CIRCUIT 5=75 F LOW TEMP ALARM CIRCUIT 3=450 F LOW TEMP ALARM CIRCUIT 6=450 F The TC 1818a will then begin to scroll through the lowest stored value of temperature for each circuit. LOW TEMP SEEN CIRCUIT 1=37 F LOW TEMP SEEN CIRCUIT 4=37 F LOW TEMP SEEN CIRCUIT 2=75 F LOW TEMP SEEN CIRCUIT 5=75 F LOW TEMP SEEN CIRCUIT 3=550 F LOW TEMP SEEN CIRCUIT 6=550 F Upon completing the display of all the LOW TEMP SEEN data, the TC 1818a returns to Scan Mode. RETURN TO SCAN MODE 47
TC 1818a Control Module Press the LOW CURRENT alarm key to display the Low Heater Current Alarm setpoint for all circuits as typically shown. LOW CURRENT ALARM LOW CURRENT ALARM CIRCUIT 1=1.0A LOW CURRENT ALARM CIRCUIT 4=1.0A LOW CURRENT ALARM CIRCUIT 2=8.0A LOW CURRENT ALARM CIRCUIT 5=8.0A LOW CURRENT ALARM CIRCUIT 3=12.0A LOW CURRENT ALARM CIRCUIT 6=12.0A After scanning through all circuits, the TC 1818a returns to Scan Mode. RETURN TO SCAN MODE 48
Operating Guide UNDERSTANDING ALARM CONDITIONS When temperature related alarm conditions do occur, the below information may be useful in establishing the cause and appropriate action. HIGH TEMPERATURE (HIGH TEMP) Low Limit: Maintain temperature plus control band value High Limit: 1100 o F or 600 o C Range: 0 o F to 1100 o F or 0 o C to 600 o C Cause: Sensed temperature exceeds programmed high temperature alarm setpoint Controller Action Taken: Alarm Only or Alarm and Trip Heater (if trip is set) LOW TEMPERATURE (LOW TEMP) Low Limit: -40 o F or -40 o C High Limit: Maintain temperature value Range: -40 o F to 1099 o F or -40 o C to 599 o C Cause: Sensed temperature is below programmed low temperature alarm setpoint Controller Action Taken: Alarm Only RTD FAULT Cause: Controller Action Taken: RTD resistance not in the 70 to 300 ohms range Alarm and heater are energized or alarm and heater are turned off depending on programming confi guration. 49
TC 1818a Control Module When heater related alarms occur, the below information may be useful in establishing a cause and an appropriate action. HIGH CURRENT (HIGH CURRENT) Low Limit: Low current alarm value High Limit: 30.0A Range: 1 to 30.0A Cause: Heater current is more than high current alarm value Controller Action Taken: Alarm Only or Alarm and Trip Heater (if trip is set) LOW CURRENT (LOW CURRENT) Low Limit: 0.0A High Limit: High current alarm value Range: 0 to 30.0A Cause: Heater current is less then low current alarm value Controller Action Taken: Alarm Only HIGH GROUND CURRENT (HIGH GND CUR) Low Limit: 30mA High Limit: 150mA Range: 30 to 150mA Cause: An excessive heater/wiring leakage current is present Controller Action Taken: Alarm Only or Alarm and Trip Heater (if trip is set) CIRCUIT FAULT (CKT FAULT) Checks For: Damaged relay or loss of current during "heater on" cycle Cause: Relay locked open or closed, breaker off, or heater/wiring disconnected Controller Action Taken: Alarm Only POWER OFF Cause: Controller Action Taken: Reset Procedure: Loss of voltage to unit None Power off message will clear itself after 30 minutes or can be manually cleared with the ALARM ACK key 50
Operating Guide CONFIGURING THE TC 1818A FOR AMBIENT SENSING OR DUAL RTD CONTROL The TC 1818a is standardly confi gured for process sensing with one RTD input assigned to each relay output circuit. The operating descriptions in this manual to this point have covered using the TC 1818a when set up as a "Standard Control" confi guration. Depending on the fi rmware level, the TC 1818a can also be factory or fi eld confi gured for up to fi ve other control confi gurations. The six possible control confi gurations are identifi ed in the below list. Configuration SINGLE RTD INPUTS Description Conventional process sensing control - one RTD input for each heat tracing circuit. 1 AMB/SINGLE Ambient sensing RTD in Circuit 1 controlling all RTD INPUTS designated ambient sensing circuits with conventional process sensing control on all process sensing circuits (one RTD input for each heat tracing circuit). 2 AMB/SINGLE Ambient sensing RTD's in Circuit 1 and 2 and controlling RTD INPUTS all designated ambient sensing circuits based on the lowest RTD reading with conventional process sensing control on all process sensing circuits (one RTD input for each heattracing circuit). 1 or 2 RTD INPUTS Single and dual RTD process sensing control - one or two RTD inputs for each heat tracing circuit as designated. 1 AMB/ 1 or 2 RTD INPUTS Ambient sensing RTD in Circuit 1 controlling all designated ambient sensing circuits with single or dual RTD process sensing control on all process sensing circuits. 2 AMB/ 1 or 2 RTD INPUTS Ambient sensing RTD's in Circuit 1 and 2 and controllingl all designated ambient sensing circuits based on the lowest RTD reading with single or dual RTD process sensing control on all process sensing circuits. 51
TC 1818a Control Module In order to factory or fi eld program the TC 1818a for any confi guration other than the standard SINGLE RTD INPUTS, fi rst momentarily press the DATA HWY key. DATA HWY Next press and hold the MAINTAIN TEMP key for about 5 seconds. MAINTAIN TEMP The following prompt window message will next appear. ITEM TO CONFIGURE Press the CONFIG key. CONFIG The current setting for the TC 1818a control confi guration will appear. SINGLE RTD INPUTS CHANGE? (Y/N) Press the UP arrow key and ENTER to change or press the DOWN arrow key and ENTER to accept the current confi guration and then return to SCAN MODE. RETURN TO SCAN MODE 52
Operating Guide It is intended that this confi guration setting be set prior to programming in all heat tracing circuit parameters. If it is necessary to change the settings once the unit is installed in the fi eld, it is recommended that all heat tracing circuit parameters be entered again. ALTERNATE CONTROL CONFIGURATIONS IN OPERATION Information screens will vary slightly depending on which alternate control confi guration is enabled. A summary of the alternate message screens which may be seen during the SCAN MODE of operation are listed below: Message Window CKT 1 TEMP = 51 F HEATER POWER= 100% AMB CKT 1 TEMP = 51 F HEATER FORCED ON CKT 1 TEMP = 51 F MAINTAIN TEMP = 50 o F PS Description Where a heater circuit on the TC 1818a controller has been programmed for ambient sensing control operation, this information screen indicates the temperature being read by the RTD on this circuit number and also indicates the percentage of power being supplied to the circuit. When the power clamping function or ambient proportional control is utilized, the percentage "time on" can vary from 100% to as low as 20%. This information screen indicates that the temperature being read by the RTD on this circuit number is 51 o F and that the heater has been "forced on". In the "forced on" mode, the circuit will remain on as long as no programmed alarm limits are exceeded. This programmed setting is primarily used for fi eld diagnostic testing. Where a heater circuit on the TC 1818a controller has been programmed for process temperature sensing operation, this information screen indicates the temperature being read by the RTD on this circuit number as well as the actual maintain temperature programmed. 53
TC 1818a Control Module Message Window CKT 1 TEMP = 51 F, 53 F HEATER POWER=100% AMB CKT 1 TEMP = 51 F, 53 F HEATER FORCED ON CKT 1 TEMP = 51 F, 53 F MAINTAIN TEMP = 50 F PS Description Where a heater circuit on the TC 1818a controller has been programmed for ambient sensing control operation with dual RTD inputs, this information screen indicates the temperatures being read by the RTDs on this circuit number and also indicates the percentage of power being supplied to the circuit. When the power clamping function or ambient proportional control is utilized, the percentage "time on" can vary from 100% to as low as 20%. This information screen indicates that the temperatures being read by the dual RTDs programmed to sense temperature for this circuit number and that the heater has been "forced on". This program setting is primarily used for fi eld diagnostic testing. Where a heater circuit on the TC 1818a controller has been programmed for dual RTD process temperature sensing operation, this information screen indicates the temperatures being read by the RTDs on this circuit number as well as the actual maintain temperature programmed. When inquiring as to the heater status (enabled, disabled, forced on, or tripped) by pressing the HEATER ENABLE key, the following alternate message screens may be seen: Message Window HEATER CIRCUIT 3= ENABLED AMB Description This information screen identifi es the Circuit 3 as being enabled as an ambient sensing RTD circuit. HEATER CIRCUIT 3= ENABLED PS This information screen identifi es the Circuit 3 as being enabled as a process temperature sensing RTD circuit. HEATER CIRCUIT 4= ENABLED 1RTD This information screen identifi es the Circuit 4 as being enabled with one RTD sensor input. HEATER CIRCUIT 4= ENABLED 2RTD This information screen identifi es the Circuit 4 as being enabled with dual RTD sensor inputs. 54
Operating Guide PROGRAMMING AND OPERATING THE TC 1818A IN AN AMBIENT SENSING CONTROL MODE The TC 1818a control module should fi rst be confi gured to allow wide band proportional temperature control in ambient sensing control applications. The simplest controller confi guration to implement ambient sensing control are the single RTD input controller confi gurations listed below: 1 AMB/ SINGLE RTD INPUTS 2 AMB/ SINGLE RTD INPUTS When programmed for one of these controller confi gurations, the TC 1818a control module will accept one ambient sensing RTD input (Circuit 1) or two ambient sensing RTD inputs (Circuit 1 and 2), and will read this input or the lower of the two values into all other ambient sense enabled circuits for control purposes. While most of the TC 1818a operation in this mode is identical to that previously described (recognizing, of course, that the temperature being acted upon is the ambient value), there are a few differences which are described in the following sections. 55
TC 1818a Control Module HEATER ENABLE (PROGRAM MODE) To program the control mode of each circuit, press sequentially the PROG key and the HEATER ENABLE key. The TC 1818a will prompt for the selection of the desired circuit (or All the Same Value). PROGRAM CIRCUIT=1 Press the UP or DOWN arrow key and ENTER. The TC 1818a will indicate the present setting (Ambient Sensing, Pipe Sensing, or Disabled). Press the UP arrow key to change the value and then the ENTER key to accept the new value. ENABLED (AMBIENT SENSE) CHANGE? (Y/N) ENABLED (PIPE SENSE) CHANGE? (Y/N) The confi guration restrictions on combinations of process (pipe) sensing and ambient sensing circuits are: Circuit 1 for single RTD sensor input must be retained as ambient sensing control circuit. Circuit 1 and 2 for dual RTD sensor inputs must be retained as ambient sensing control circuits. Proportional control mode must be utilized on both ambient and process (pipe) sensed circuits. 56
Operating Guide MAINTAIN TEMP (PROGRAM MODE) In order to set the maintain temperature when using ambient sensing control, press the PROG key. The TC 1818a will prompt for the function to program. PROGRAM MODE ENABLED SELECT FUNCTION KEY Press the MAINTAIN TEMP key. The TC 1818a will next prompt for the selection of the desired circuit (or All the Same Value). PROGRAM CIRCUIT=2 Press the UP or DOWN arrow key and ENTER. The TC 1818a will prompt for the maintain temperature as follows: MAINTAIN TEMP=120 F NEW VALUE=120 F When in ambient sensing control mode, the minimum ambient temperature should be entered here (this is the 100% heater power value in wide band proportional control). To change the present maintain temperature value, press the UP or DOWN arrow key until the proper value is displayed. MAINTAIN TEMP=120 F NEW VALUE=-20 F Press the ENTER key to accept the new value. The TC 1818a will then return to the Scan Mode operation. 57
TC 1818a Control Module CONTROL BAND (PROGRAM MODE) In order to set the control range for ambient sensing control, press the PROG key. The TC 1818a will prompt for the function to program. PROGRAM MODE ENABLED SELECT FUNCTION KEY Press the CONTROL BAND key. The TC 1818a will next prompt for the selection of the desired circuit (or All the Same Value). PROGRAM CIRCUIT=1 Press the UP or DOWN arrow key and ENTER. The TC 1818a will prompt for the control band as follows: CONTROL BAND=5 F NEW VALUE=5 F 58
Operating Guide When in wide band ambient sensing control mode, the control band will be between the minimum ambient temperature (the 100% heater power value) and the ambient temperature at which power off is to occur (the process fl uid minimum desired temperature value). To change the present control band value, press the UP or DOWN arrow key until the proper value is displayed. CONTROL BAND=5 F NEW VALUE=70 F Press the ENTER key to accept the new value. Note that with these settings, full power to the heaters will occur at -20 F and power will turn off at 50 F. The TC 1818a will then return to the Scan Mode operation. RETURN TO SCAN MODE SCANNING DATA (DISPLAY MODE) When in the SCAN mode of operation, the TC 1818a will display the following screen on all ambient sensed control circuits in a single RTD controller confi guration. Circuit 1 Ambient Sensing RTD CKT 3 TEMP= -20 F HEATER POWER=100% AMB or Circuit 1and 2 Ambient Sensing RTD's CKT 3 TEMP= -20 F, -19 F HEATER POWER=100% AMB The TC 1818a thus indicates the RTD input temperature which represents the ambient temperature values measured on Circuit 1 (and Circuit 2 if confi gured) and is additionally indicating the power level that this particular circuit is operating at. 59
TC 1818a Control Module PROGRAMMING AND OPERATING THE TC 1818a WITH DUAL INPUT RTDS FOR A SINGLE CONTROL CIRCUIT The TC 1818a control module may be factory or fi eld confi gured to allow for using single or dual RTD inputs on either ambient sensing or process sensing applications. The following three controller confi guration options are available for this purpose: Controller Configuration 1or 2 RTD INPUTS 1AMB/ 1 or 2 RTD INPUTS Application Process sensing applications Process sensing applications and single ambient sensor in fi rst circuit 2 AMB/ 1 or 2 RTD INPUTS Process sensing applications and ambient sensors in fi rst and second circuit The above factory confi guration options are specifi cally designed for controlling a heat tracing circuit with either single or dual RTD input sensor control circuits. When setting up circuit assignments for these factory confi guration types, the heat tracing circuits that are to be set up with dual RTD's will always be assigned in pairs. That is, the RTD's on Circuit 1 and 2, Circuit 3 and 4, Circuit 5 and 6, and so on should be considered as paired circuits. As one example, when dealing with dual RTD's with process sensing, if Circuit 6 were to be programmed for a dual RTD input control the TC 1818a controller would use the RTD's in Circuit 5 and 6 in controlling the power relay for Circuit 6. The relay associated with Circuit 5 could be disabled or could be used to control a second pass of heater if Circuit 5 were also confi gured as a dual RTD process sensing input (using RTD 5 and RTD 6 for control). 60
Operating Guide As another example, in a "1 AMB/ 1 or 2 RTD INPUTS" controller confi guration, if Circuit 6 were to be programmed for a dual RTD input control it would again use the RTD's in Circuit 5 and 6 in controlling the power relay for Circuit 6. In this case, however, the relay on Circuit 5 could additionally be used as a control power relay on an ambient sensed circuit operating based on the RTD input from Circuit 1. The specifi c control strategy for a dual RTD control circuit in any of these factory confi guration types is as follows: The heat tracing circuit controls off of the lowest RTD reading except in the event that a temperature value on either RTD falls within the alarm dead band of the high temperature alarm value. In this event, that RTD will become the controlling temperature reading. The heat tracing circuit will go into low or high alarm if either RTD reading in the pair exceeds the programmed low or high alarm limit value. For more details on setting up a mixed single and dual RTD control mode, refer to Examples 5 and 6. 61
TC 1818a Control Module TYPICAL CONTROL APPLICATIONS EXAMPLE 1 - AMBIENT SENSING FREEZE PROTECTION - PROPORTIONAL CONTROL WITH SOLID STATE RELAY OUTPUT When confi gured with solid state relays, the TC 1818a may be used in ambient sensing wide band proportional control. This method of control is ideal in tracing designs where simple ambient sensing RTD's and freeze protection is required. In this mode of control, the TC 1818a will (by cycle omission techniques) proportionally increase the power to the heat tracing as the ambient temperature drops. A typical application for this type of control might be the freeze protection of water lines in a water treatment facility. Assume the following heat tracing operating design Heat Tracing Type: Self-Regulating Parallel Heater Cable Safety Factor: 30% Minimum Ambient: -20 F Minimum Water Maintain Temp: 40 F A typical list of the key TC 1818a settings is as given below: Control Parameter Setting Controller Confi guration 1 AMB/ SINGLE RTD INPUTS Control Method Proportional Maintain Temperature* -20 F Percent Power at Maintain Temp. 100% Control Band 60 F * Note that the maintain temperature is the temperature where 100% power is supplied to the heater. Having set in these values along with appropriate alarm settings, the following control can typically be achieved. Pipe Temperature Power 100% Pipe 20% Power 75 55 35 0% -20 Ambient Temperature (degf) 40 62
Operating Guide EXAMPLE 2 - FOUNDATION HEAVE PROTECTION - PROPORTIONAL WTH SELF-ADJUST CONTROL WITH SOLID STATE RELAY OUTPUT Cryogenic vessels and refrigerated rooms often utilize heating systems beneath to prevent heaving due to the freezing of the soil/foundation base structure. A typical heat tracing application of this type might require an operating tracing design as follows: Internal Room Temperature: -27 F Minimum Maintain Temperature of Soil: 40 F Maximum Foundation Temperature: 80 F Heater Cable Type: Constant Wattage Design Safety Margin: 42% The TC 1818a control module using foundation temperature sensing RTD's in each heating zone can be typically set at the control settings given below: Control Parameter Setting Controller Confi guration SINGLE RTD INPUTS Control Method Proportional with Self-Adjust Maintain Temperature 50 F Control Band 30 F High Alarm Temperature 90 F High Temperature Trip On Low Alarm Temperature 38 F 63
TC 1818a Control Module These settings assume the system was designed with a 42% safety margin. By clamping the power to the 70% value, the heater output should match the heat load. The heater should be continually operating using cycle omission techniques in a warming mode (and will thus minimize condensation within the heating system). After attaining 50 F, the TC 1818a will linearly reduce power (the minimum level of power is 20% after 9 F rise) until an equilibrium value between 50 F and 80 F is obtained. In the unlikely event that the 80 F setting is exceeded, the control will de-energize the heater circuit. A high temperature alarm will activate should the RTD sensor detect a temperature above the 90 F value and the circuit will trip. Having set in these values as well as the appropriate other limit/control values, the following typical control can be achieved. Power 100% 70% Typical Controlled Soil Temperature 20% 0% 50 52 59 Soil Temperature (degf) 80 64
Operating Guide EXAMPLE 3 - PROCESS TEMPERATURE MAINTENANCE - PROPORTIONAL CONTROL WITH SOLID STATE RELAY OUTPUT The TC 1818a features the option of proportional control for those applications where close temperature control is required on process piping which may have varying process temperature conditions. A typical heat traced piping application might be a corn syrup viscosity control application. Due to the sensitivity of the syrup to color degradation the syrup must be maintained below 90 F. Typical heat tracing design requirements are listed as follows: Syrup Maintain Temperature: 80 F Heater Cable Type: Constant Wattage Maximum Syrup Temperature: 90 F The TC 1818a control module utilizing pipe sensing RTD's could be typically set as shown below: Control Parameter Setting Controller Confi guration SINGLE RTD INPUTS Control Method Proportional Maintain Temperature 80 F Control Band 10 F High Alarm Temperature 90 F High Temperature Trip On Low Alarm Temperature 75 F Power at Maintain Temperature 100% Having set in these values as well as the appropriate other limit/control values, the following typical control can be achieved. Power 100% Pipe Control Point 20% 0% 80 83 Controlband Pipe Temperature (degf) 90 65
TC 1818a Control Module EXAMPLE 4 - PROCESS TEMPERATURE CONTROL - MECHANICAL RELAYS Extremely versatile, the TC 1818a can be confi gured with RM-1 or RM-2 mechanical relay output options. This option is often selected in high heat output tracing applications where either high current or high voltage switching is required. One such tracing application might be the temperature maintenance of a long sulfur transfer line. Typical tracing design requirements are listed as follows: Heater Cable Type: Mineral Insulated Series Cable Voltage Switched: 277 Vac Current Switched: 49A Sulfur Maintenance Temperature: 282 F Sulfur Freeze Point: 260 F Sulfur Congeal Point: 320 F The TC 1818a control module with pipe sensing RTD's could be typically as shown below: Control Parameter Setting Controller Confi guration SINGLE RTD INPUTS Control Method On/Off Maintain Temperature 282 F Control Band 5 F High Alarm Temperature 300 F Low Alarm Temperature 260 F Having set in these values as well as the appropriate other limit/control values, the following typical control can be achieved. Pipe Temperature (degf) 290 280 Time 66
Operating Guide EXAMPLE 5 - PROCESS TEMPERATURE CONTROL - SINGLE AND DUAL RTD SENSING It is sometimes considered advantageous to use dual RTD sensors on a critical heat tracing application such as a 50% caustic line. In this way, the power to the heater can be based on the input of two discrete temperature inputs rather than one. In addition, in the event of an RTD fault, the operator can be alarmed, the circuit can be acknowledged, and the RTD can be repaired without turning the heat tracing circuit OFF. For this application, the typical design requirements are as listed below: Product Maintenance Temperature: 80 F Product Freeze Point: 54 F Heater Cable Type: Self Regulating Parallel Cable Maximum Caustic Temperature: 100 F The TC 1818a control module utilizing pipe sensing RTD's could be typically set as indicated below: Control Parameter Setting Controller Confi guration 1 or 2 RTD INPUTS Control Method Proportional Maintain Temperature 80 F Control Band 5 F High Alarm Temperature 90 F High Temperature Trip ON Low Alarm Temperature 60 F Power at Maintain Temperature 100% 67
TC 1818a Control Module Considering that we have only three heat tracing circuits, the TC 1818a would be set up as a six point unit with a controller confi guration of "1 or 2 RTD INPUTS". The heat tracing circuit assignments would be as follows: Circuit No. Setting 1 Enabled (2 RTD) 2 Disabled 3 Enabled (2 RTD) 4 Disabled 5 Enabled (2 RTD) 6 Disabled In this case power relays on circuits 2, 4 and 6 will not be connected to the heat tracing. Alternately, in a case where both power relays were to be used to maximize the current switching capability, the following circuit assignments could also be used. Circuit No. Setting 1 Enabled (2 RTD) 2 Enabled (2 RTD) 3 Enabled (2 RTD) 4 Enabled (2 RTD) 5 Enabled (2 RTD) 6 Enabled (2 RTD) In this circuit assignment, all circuit relays are controlling off of dual RTD inputs. Note that this confi guration is also applicable in center feed arrangements for two heat tracing circuits running in opposite directions from power. 68
Operating Guide EXAMPLE 6 - PROCESS TEMPERATURE AND AMBIENT SENSING CONTROL - SINGLE AND DUAL RTD SENSING In many applications there are a variety of control applications. Some may be the critical applications such as the 50% caustic in Example 5 and some may be simple water freeze protection. For this combination application, the typical design requirements are as listed below: 50% Caustic Product Maintenance Temperature: 80 F Product Freeze Point: 54 F Heater Cable Type: Self Regulating Parallel Cable Maximum Caustic Temperature: 100 F Number of Circuits: Two Process Sensing Water Product Maintenance Temperature: 50 F Product Freeze Point: 32 F Heater Cable Type: Self Regulating Parallel Cable Number of Circuits: Four Ambient Sensing The TC 1818a control module utilizing pipe sensing RTD's could be typically set as indicated below: Control Parameter Setting Controller Confi guration 1 AMB/ 1 or 2 RTD INPUTS Control Method On-Off Caustic Circuits Maintain Temperature 80 F Control Band 5 F High Alarm Temperature 90 F High Temperature Trip ON Low Alarm Temperature 60 F Water Circuits Maintain Temperature 50 F Control Band 5 F High Alarm Temperature 120 F High Temperature Trip Off Low Alarm Temperature 40 F Considering that we have only six heat tracing circuits, the TC 1818a would be set up as a six point unit with a controller confi guration of "1 AMB/ 1 or 2 RTD INPUTS". 69
TC 1818a Control Module The heat tracing circuit assignments would be as follows: Circuit No. Setting 1 Enabled (Ambient Sensed) 2 Enabled (Ambient Sensed) 3 Enabled (2 RTD) 4 Enabled (Ambient Sensed) 5 Enabled (2 RTD) 6 Enabled (Ambient Sensed) In this case, power relays on circuits 1, 2, 4 and 6 will be controlling ambient sensed circuits based on the RTD input on Circuit 1. Circuit 3 and its power relay will be controlling based on the RTD inputs from Circuit 3 and Circuit 4. Circuit 5 and its power relay will be controlling based on the RTD inputs from Circuit 5 and Circuit 6. 70
Operating Guide COMMUNICATIONS The TC 1818a is standardly provided with an RS485 communications port. This port allows for communication through a Modbus ASCII and RTU protocols to a PC workstation or to the facility distributed control system (DCS). Through this communications link, most of the operating parameters which are programmable at the module can be accessible at the central PC workstation or DCS system console. For communications linking between the TC 1818a and a PC workstation, refer to the TraceView TM Network Explorer Operating Guide. For communications linking information between the TC 1818a and the facility distributed control system (DCS), refer to DCS Operations Guide, SWM-008.X. 71
TC 1818a Control Module OPTIONS AND ACCESSORIES Thermon can provide a variety of options and accessories to complete the installation. Some typical accessories are listed below. SW-TVNE TraceViewTM Network Explorer is a PC-based communications software package developed specifi cally for centralized control and monitoring of the various fi eld mounted HeatChekTM units. TraceView Network Explorer, operating within the Windows environment, allows the changing of control and alarm setpoints, adjustment of controller operating parameters, and acknowledgement of all alarms from the control room or motor control center. TraceView Network Explorer permits the viewing of heat tracing isometrics on demand and allows online access to heat tracing and controller diagnostic information. Continuous data logging and reporting of heat tracing operations/alarm status as well as historical trend data storage (for later retrieval to spreadsheet or database software) is also provided. TraceView Network Explorer can be confi gured for up to sixteen communication ports (with each program instance allowing up to 247 HeatChek control and monitoring units 1 ). Communications can be achieved at distances up to 4000 ft. (1220 m) on the RS485 two wire twisted shielded communication link. RTD-100 This three wire resistance temperature detector (RTD) is rated to 500 F (260 C). Provided with a standard aluminum termination head, the RTD sensor is insulated with fi berglass and shielded with Type 316 stainless steel housing. IM-1 Interface module for linking RS485 two-wire twisted shielded pair into RS232 port of PC. DCALXX Interposing DC alarm relays can be added for use in ordinary and hazardous locations to interface to plant DCS systems. 1 A minimum of one repeater module is recommended for every thirty-one control and monitoring modules confi gured into a data highway. 72
Operating Guide HELP This HeatChek control and monitoring unit is intended to be used with only the support of this instruction booklet. If special support needs do arise, Thermon provides local support through its area representatives and affi liate companies as well as through a toll free user support line. For toll free support dial 1-800-820-HEAT(4328). Information may also be obtained by accessing the Thermon Website at www.thermon.com. 73
TC 1818a Control Module ATTACHMENT A: TC 1818A COMMAND FLOWCHART Note: Security key must be in the vertical position for the TC 1818 to allow programming. MAINTAIN TEMPERATURE PROGRAM NEW PROG MAINTAIN TEMP ENTER ENTER CIRCUIT VALU E CONTROL BAND PROGRAM NEW PROG CONTROL BAND ENTER ENTER CIRCUIT VALUE HIGH TEMPERATURE ALARM PROGRAM NEW RESET HIGH PROG HIGH TEMP ALARM ENTER ENTER ENTER CIRCUIT VALUE TEMP SEEN LOW TEMPERATURE ALARM PROGRAM NEW RESET LOW PROG LOW TEMP ALARM ENTER ENTER ENTER CIRCUIT VALUE TEMP SEEN HIGH CURRENT ALARM PROGRAM NEW PROG HIGH CURRENT ALARM ENTER ENTER CIRCUIT LOW CURRENT ALARM PROGRAM VALU E NEW PROG LOW CURRENT ALARM ENTER ENTER CIRCUIT VALU E 74
Operating Guide ATTACHMENT A: TC 1818A COMMAND FLOWCHART Note: Security key must be in the vertical position for the TC 1818 to allow programming. GROUND CURRENT ALARM PROGRAM NEW PROG GROUND CURRENT ENTER ENTER CIRCUIT VALU E DATA HIGHWAY PROGRAM NEW PROG DATA HWY ENTER ENTER CIRCUIT VALU E CIRCUIT # ENABLE (PIPE SENSE) CIRCUIT # ENABLE (AMBIENT SENSE) HEATER ENABLE/DISABLE CIRCUIT # DISABLE PROG HEATER ENABLE PROGRAM CIRCUIT CHANGE? YES NO ENTER FORCE HEATER ON YES NO CIRCUIT FORCED ON CIRCUIT ENABLED/DISABLED ALARM ACKNOWLEGE ALARM ACK CIRCUIT # REPORTED FAULT ALARM ACK CIRCUIT # REPORTED FAULT ACK REPORTED FAULT HAS BEEN ACKNOWLEDGED 75
THERMON... The Heat Tracing Specialists 100 Thermon Dr. P.O. Box 609 San Marcos, TX 78667-0609 Phone: (512) 396-5801 Facsimile: (512) 396-3627 1-800-820-HEAT http://www.thermon.com Part Number: 80505