Apparatus required to perform D.c Shunt generator Characteristics

Transcription

1 Apparatus required to perform D.c Shunt generator Characteristics 1. Voltage transducer: For the electronic measurement of voltages: DC, AC, pulsed..., with a galvanic isolation between the primary circuit (high voltage) and the secondary circuit (electronic circuit). The specification of transducer as follows: Model LV 25-P/SP5 Primary nominal r.m.s. current 10 ma Primary current, measuring range 0... ± 14 ma Measuring resistance RM min RM max With ± 15 ± 10 ma max 100 Ω 340 ± 14 ma max 100 Ω 180 Ω Secondary nominal r.m.s. current 25 ma Conversion ratio 2500 : 1000 Supply voltage (± 5 %) ± 15 V Current consumption 10 + IS ma RMS voltage for AC isolation test,50 Hz, 4.2 kv Overall Accuracy TA = 25 C ± 0.8 % Linearity < 0.2 % Offset current TA = 25 C ± 0.15 ma Response 90 % of VPN 25 μs Ambient operating temperature C Ambient storage temperature C Primary coil TA = 85 C 300 Ω Secondary coil TA = 85 C 117 Ω 2. Current transducer: For the electronic measurement of current: DC, AC, pulsed mixed, with a galvanic isolation between the primary circuit (high power) and the secondary circuit (electronic circuit). The specification of transducer as follows: Model LA 25-NP Primary nominal r.m.s. current 25 At Primary current, measuring range 0... ± 36 At Measuring resistance RM min RM max RMmin RMmax with ± 15 ± 25 At max 100 Ω 340 ± 36 At max 100 Ω 180 Ω Secondary nominal r.m.s. current 25 ma Conversion ratio : 1000 Supply voltage ± 15 V Current consumption 10 + IS ma RMS voltage for AC isolation test,50 Hz, 2.5 kv Overall Accuracy TA = 25 C ± 0.5 % Linearity < 0.2 % Offset current TA = 25 C ± 0.15 ma Response 90 % of Ipmax < 1 μs Ambient operating temperature C Ambient storage temperature C Primary coil TA = 25 C < 1.25 mω Secondary coil TA = 70 C 110 Ω

2 Features Closed loop (compensated) multi-range current transducer using the Hall Effect. Insulated plastic case recognized according to UL 94-V0. Applications AC variable speed drives and servo motor drives. Static converters for DC motor drives. Battery supplied applications. Uninterruptible Power Supplies. (UPS) Switched Mode Power Supplies (SMPS). Power supplies for welding applications. 3. RPM Indicator: RPM indicator is used to indicate speeds of wide range of rotating machine. Available with various options like direct displays, high / low setting of speed range, PC connectivity through DAQ card. Here simple motor-tachometer application is used where each rotation of the motor shaft is to be detected. Conceptual approach is shown in Figure consists of a ring magnet on the motor shaft and a radiallymounted digital output Hall Effect sensor. As the ring magnet rotates with the motor, its south pole passes the sensing face of the Hall sensor with each revolution. The sensor is actuated when the South Pole approaches the sensor and deactuated when the South Pole moves away. Thus, a single digital pulse will be produced for each revolution. Fig. Hall Effect conceptual approach Features Dust proof membrane keyboard Wide range of rpm Four digit display Pulse counting Specifications Range: 0.01 to 9999 rpm (4 digit unit)

3 Input: Proximity / Encoder / Optical sensor / mv Decimal point: Floating / Selectable Supply: 230 V 50 Hz AC Size: 96x96 mm depth 100 mm 4. Data Acquisition Card: The output of the voltage transducer and speed indicator is in analog form. So to perform the experiment from computer it is necessary to convert this signal into digital and also it should be compatible to software which is used to show the results of experiments. Hence interfacing card is used called as Data Acquisition Card (DAQ) USB 6212 is used. It is developed by National Instruments. This card is comes under the M series of DAQ. DAQ hardware digitizes 5 signals, performs D/A conversions to generate analog output signals, and measures and controls digital I/O signals. Figure 2.3 features components common to all M Series devices. I/O C Analog Input O N N E Analog Output Digital I/O Digital Routing and Clock Generation Bus Interface Bus C T Counters RSI O PFI R Fig. General M Series Block Diagram The NI USB-6212 is designed specifically for mobile or space-constrained applications. Plug-and-play installation minimizes configuration and setup time, while direct screw-terminal connectivity keeps costs down and simplifies signal connections. This product does not require external power. The USB-6212 also features new NI signal streaming technology, which gives DMA-like bidirectional high-speed streaming of data across the USB bus. The specification of this card is given below: Product Name Product Family Form Factor DAQ Product Family Measurement Type USB-6212 Multifunction Data Acquisition USB M Series Quadrature encoder, Voltage Analog Input

4 Channels 16, 8 Single-Ended Channels 16 Differential Channels 8 Resolution 16 bits Digital I/O Bidirectional Channels 32 Physical Specifications Length 16.9 cm Width 9.4 cm Height 3.1 cm I/O Connector Screw terminals Timing/Triggering/Synchronization Triggering Digital 5. Three Phase Induction Motor As generator requiring low starting torque and constant speeds, squirrel-cage induction motor is the best choice, because of its ruggedness, simplicity. The specification of motor is as follows: 7 Input: V 50 Hz Winding Connection: Delta Rotor :Squirrel cage rotor Output:7.5 KW Type:TEFC(Totally Enclosed Fan- Cooled) Insulation class: B Current:15 A Efficiency: 85 % Speed :1420 RPM 6. DC Generator In order to achieve wider speed range, change in the voltage applied to motor is necessary. For that purpose separately excited dc generator is used. A change in the generator field current varies the voltage applied to the motor armature, and, therefore, the motor speed is changed. The specifications of the generator are as follows: 10 H.P. Speed:1450 RPM Rating : Continuous

5 Current: 38.2 A Output voltage: 220V Wound: Shunt 7. Star Delta Starter: This starter is used because stator winding of induction motor is in delta. The motor stator has six terminals that can be connected in star at the time of starting and when motor gains sufficient speed, it will reconnect the six terminals in delta. Actually when stator in star then the phase voltage is 1/ 3 times the line voltage, so the starting current decreases to 1/3 of the normal current. When motor gain sufficient speed stator terminals are connected in delta so phase voltage equals line voltage. In automatic star delta starter, there are two push buttons, one for starting and other for stop. Normally we have to start and stop the motor manually. But in this setup we are doing this remotely. Actually the functions of two push buttons are now performed by two relays. Now when we operate the relay the two contacts of the starting push button closes and the plunger closes and connects the terminals in star. After a present time the other plunger operates and connects the motor terminals in delta and then motor runs smoothly. When we have to stop the motor the normally closed contacts of the stop buttons has to be opened. So relay connected across it is when disconnected it opens the two terminals and power supply is disconnected from the motor. The control signal for the relays is given by the computer. So in this way we can start and stop the machine from any remote panel using computer. 8. Webcam An online webcam (D-Link DCS 5220) has been used to provide continuous live video of the operating setup to the remote user. When the user is performing the experiment through LabView UI, Live Video streaming allows him/her to observe the DC Generator-Motor etc. This helps the remote user get the feel of performing the experiment even when he is not physically present near the machine. Hence, the Virtual Machine becomes real. 9. Solid State Relay: The relay is used to start and control the load remotely. The relay is controlled by the computer output signal. Here we have used relays which can allow the dc supply and ac supply. The specifications of the relay which is used for AC: Company: Auto nix Input voltage: 3-35 V DC Output: V AC Current:10 A The specifications of the relay which is used for DC: Company: Auto nix Input voltage: 3-35 V DC Output: V DC Current:10 A Voltage applied to the control line of an SSR causes the LED to shine on the photo-sensitive diode. This produces a voltage at gate, causing the Triac to turn on and the load is connected to the line. There is some circuitry to discharge the gate when the LED is turned off, speeding the relay's turn-off.