Power Quality for Information Technology System
ITS OBVIOUS THE TOLERANCE IS DIFFRENT
But What isn t Tobvious? HOW MANY OF YOU HAVE : A COMPUTER AT HOME? =
Computers are not screens and Keyboards COMPUTERS ARE NOT SCREENS AND KEYBOARDS THEY ARE : INFORMATION TECHNOLOGY EQUIPMENT
SURGE SUPPRESSION SYSTEM SURGE SUPPRESSION SYSTEM SURGE SUPPRESSION SYSTEM SURGE SUPPRESSION SYSTEM SURGE SUPPRESSION SYSTEM PRASA Computers Today TELCO PROTECTORS STRUCTURAL LIGHTNING PROTECTION RISER COMPUTER ROOM 3 φ UPS TVSS ACCUvAR PANELS PANELS TVSS ACCUvAR CONFERENCE ROOMS PD U K-RATED Liebert Liebert NETWORKS TVSS ACCUvAR PANELS ACCUvAR Liebert OFFICES TVSS & VOLTAGE REGULATORS OFF-LINE UPS Liebert SECURITY FIRE TELCO PANELS PANELS ATF WORK STATIONS ON- UPS LIEBERT SERVICE ENTRANCE ACCUvAR STATIC X-FER SWITCH Liebert TVS S GENERATORS
POWER QUALITY DEFINITIONS PER IEC / IEEE Transient Surge Line Noise Short duration Voltage,Current or Power problem lasting typically < 3 m S. Voltage increase of typically > 2 X the peak nominal system. High frequency voltage or current typically < 5 KHz. Magnitude 0-8 pu. T.O.V. Temporary increase in RMS voltage 1.1-1.4pu Temporary Duration 26/31Cycles - 1 min. Overvoltage T.O.V. area Voltage nominal Swell 1.1-1.8pu Instantaneous increase in RMS voltage nominal Duration.5-25/30 cycles Sag.3 -.9 Instantaneous decreases in RMS voltage nominal Duration.5-25/30 cycles Increase in RMS voltage 1.1-1.2 pu Duration >1 min. Overvoltage Undervoltage Decrease i RMS voltage 0.8-09pu Duration > 1 min. IEEE Std.1159-1995 Voltage nominal Voltage nominal Voltage nominal Voltage nominal
Power Quality Problems POWER QUALITY THE BIG PUZZLE HARMONICS WIRING METHODS EARTHING SYSTEMS EMI RFI LIGHTNING
Revised ITIC / IEEE 110 Curve 500 % Of Nominal Voltage 400 300 200 100 0 120% 110% 90% 80% 70% 0.0001 0.001 0.01 0.1 1.0 10 100 0.020 0.5 Duration in Seconds
IEEE Power Quality
TODAY S FACILITY WIDE POWER QUALITY PRASA Power Quality Strategy Redundancy REACTIVE IMPROVED UPTIME Monitoring Maintenance UPS Generators Static Switches Voltage Regulators PROACTIVE DAMAGE PREVENTION Active Tracking Filters (TVSS/Protectors) Transient Noise Filters Wiring Bonding Earthing
11 PRASA Common Earthing, Bonding and Wiring MULTIPLE EARTHS AC POWER COMMUNICATION CLEAN POWER
Incorrect isolated Earthing Mains Service Entrance Distribution Panelboard Isolated Earth Receptacle ITE Equipment N N N G IG IG PE Earthing Electrode Isolated Earthing Electrode
Multiple Earthing INTERCONNECT VOICE, SIGNAL AND DATA LINES TO AC POWER EARTH
IBM Earthing All grounds entering the room should be interconnected somewhere with in the building to provide a common ground potential. This includes any separate power sources, lighting and convenience outlets, and other grounded objects, such as buliding steel,plumbing, and duct work. The equipment grounding conductor to the green - wire common of the computer power ceners must be electrically attached (bonded ) to the enclosure and to the connector grounding terminal. See Figur 5-1 on page 5-4. Conduit must not be used as the only grounding means, and it must be connected in parallel with any grounding wires it contains. IBM GENERAL INFORMATION MANUAL IM-PP 5.2
15 PRASA NFPA 780 / BS665 / IEC6124 Earthing
Distribution Wiring Poor System Design COMPUTERS Service Entrance 208/120V 415/240V Electronic Loads Other Loads Low Cost, Low Power Quality MOTOR DRIVES LIGHTING SYSTEMS
Distribution Wiring Better System Design COMPUTERS Service Entrance 208/120V 415/240V Electronic Loads 208/120V 415/240V Other Loads Dedicated Feeds Results in Better Power Quality DRIVES LIGHTING SYSTEMS
Good Power Quality Earthing Requires : Good Surge Suppression and Filtering to Work Properly
Circuit Breakers and Fuses Protect For over Current
ITS OBVIOUS SURGE Transients SURGE NOISE Transients are (typically a few milliseconds duration) Surge - LARGE AMPLITUDE VOLTAGE / CURRENT PROBLEM > 2x nominal Vp EFFECT- HARDWARE DAMAGE SOLUTION- TVSS WITH FILTERING ( LIFE INSURANCE) NOISE- SMALL AMPLITUDE FAST RISE VOLTAGE PROBLEM < 2 x nominal Vp EFFECT- SOFTWARE / HARDWARE ERRORS, SYSTEM LOCK-UP SOLUTION- FILTERING SYSTEMS OF CAPACITORS ARE GOOD CAPACITORS & INDUCTORS ARE BETTER ( HEALTH INSURANCE )
SURGES Ite Threshold Levels Transients DISTURBANCE IN VOLTS E- FLASH OVER I - ENERGY EFFECT d v / d t BOUNDRY FUZZY REAL WORLD EVENTS NANO MICRO MILLI SECONDS
IBM Power Quality Power Quality The Quality of equipment can make a big difference in the performance of IBM equipment.power disurbances or transients can cause equipment power failures or errors.transients can come into the site on the power company lines but are often caused by produced by welders, cranes, motors, induction heaters, elevators, copy machines and other disturbances is to have transient - producing equipment The best way to prevent problems caused by power disturbances is to have transient - producing on a separate power service than the one that supplies power to the IBM equipment. IBM GENERAL INFORMATION MANUAL IM-PP 5
Statistics on Power Problems Under voltage, Over voltage, outages and others Voltages Spikes 40% Transient Voltage and noise 48.5% IEEE Report Impact of Utility Distribution Systems on Power Line Disturbance 1976 GW-Allen and Seagall. According to prominent IEEE report, 88.5% of all external and internal power disturbances are transients, spikes and noise.
IEEE STD 1100 Emerald Book SECTION 8.4.2.5 SURGE PROTECTIVE DEVICES Recommended practice is that surge protective devices be applied to service entrance electrical switchboards and panelboards, and panelboards on the secondary of separately derived systems that support information technology equipment (ITE), telephone, telecommunications,signaling,television and other forms of electronic load equipment.
Semiconductor Failure DEGRADATION FROM SURGE CURRENT HEATING SUBSTRATE RESISTANCE CHANGES INTERMITTANT OPERATION PUNCTURED SUBSTRATE
Transient Sources Lightning Strikes Utility Line Work / System Faults Motors Arc Welders Transfer Switches Power Factor Correction Capacitors surge E = I x R + L di / dt switch time
Transient Sources Power Quality Audit Objectives To stop the interruption of your business To protect you from huge business loss To protect you from certain power related danger
Power Quality Audit Objectives To stop the interruption of your business To protect you from huge business loss To protect you from certain power related danger
Power Quality Management Power quality Accounting, the first step. track power quality problem Power Management, a powerful tool to: Measure power quality at each stage Pin-point areas of Wastage, failure, danger Resulting in Corrective Measures, Savings
Audit Standards Federal information processing standards publication standard-guideline of electrical power. IEEE standard 1100-1992 Grounding & powering sensitive electronic equipment 1992 Conforms to National electric code( NFPA 70)
31 PRASA Procedure Install power quality analyzers at all the main breaker & any suspected location Collect power quality data & perform voltage & current harmonics analysis at the main building power & at the other location Perform a facility walk through.inspect switch gear, wiring, grounding practices, existing power conditioning, load equipments Analyze the recorded data. Compare susceptibility of sensitive loads to power quality data recorded. If any problems are found, asses if they are due to utility cause or customer;s loads. Isolate the cause & extent of the problems
32 PRASA Test Values The Standard equipments used by Emerson monitors & records a wide range of power characteristics & disturbances. Voltage regulation Phase voltage imbalance Total connected load current Building transformer detailing Frequency regulation Phase rotation Power factor Line disturbances Voltage & current total harmonic distortion Crest factor Phase symmetry
Deliverables Detailed report describing the Analysis Recommended solutions Customer will receive the information regarding - Power A analysis - Power B analysis - Power C analysis & in each stage they will get the details voltage, current frequency & harmonic data. Turn around time for the report is two weeks after final data collection
34 PRASA Our Guiding Principle Power is Expensive But Quality power Is Unique