21 st Century Facilities

21

Century Facilities

– 24 X 7 reliability needed

– Non linear loads cause harmonics • VFD

• Computers

– Switching transients disrupt operations – Less customer support from Utilities – Pressure to hold energy costs down

– Compressed schedules for expanding facilities – Effect of EMF on computers and equipment

– How to expand facilities to meet customer needs cost effectively

Formula For Successful Facilities

• Engineering Design • Quality Installation • Acceptance Testing

• Regular and Complete Maintenance – Preventative Maintenance Testing

Testing for All Phases of Facility

Improvements

• Load analysis for facility improvements

• Trouble shooting and correction of problems • Acceptance Testing for New Projects

• Switchboards and/or Switchgear • Circuit Breakers

• Preventative Maintenance • Forensic Testing

Testing – Load Analysis

• Measuring existing loads with portable test equipment – 120V to 480V, 0 – 3000 Amps

– Recorded values

– Volts - Power Factor – Amps - KVA

– KW - KVAR – Measure harmonic distortion

– THD - Voltage & Current – Individual harmonics

• Measure loads for emergency generator sizing • Motor starting studies

CURRENT Trend Monitoring

Testing – Acceptance Testing

– Medium Voltage – Transformers – Switchgear – Cables – PFC – Air Switches – SF6 Circuit Breakers – Below 600V

– Switchboards and Switchgear – Motor Control Centers

Acceptance Testing Cont’d.

– Short Circuit Study verifies overcurrent protective

devices meet requirement for interrupting available fault current.

– Coordination Study graphically shows how overcurrent protective devices coordinate to have the CB closest to the fault open.

• Ground Resistance Testing

– 3 Point Fall of Potential Method

Transformer Testing

• On Line, no shutdown

• Excellent analytical technique developed by IEEE to evaluate condition of transformer

• IEEE/ANSI C57 Distribution, Power and Regulating

Transformers. C57.104 is the Standard for Interpretation. • NFPA 70B

– Section 7-2.81 Oil Tests

Transformer Testing Cont.’d

• Mineral Oil is complex hydrocarbon molecular compound – At normal conditions it is very stable

– Heat, corona and arcing break molecule down to sub elements (combustible gases) (H₂, CH₄, etc.)

– Analysis of dissolved combustible gases gives the condition of the transformer.

– Trending of gases is very helpful in the analysis.

• DGA is one of the best ways to monitor the condition of the transformer and help the Owner plan repairs or

Infrared Thermography Scan

• Heat breaks down electrical insulation • 10° C Rule = ½ life

• Infrared thermography scanning

– Looks at thermal image of switchgear, busbars, connections, cables, etc.

– Hot spots and irregularities are discovered by trained technicians

– Problem areas can be corrected before they cause shutdowns or cause fires.

• Scanning Saves Equipment

– Technician scanning is much faster that tightening all bolts. – Cannot see some circuit breaker problems without IR.

Infrared Thermography Scan

Spot 1 Rise over Spot 2 60.84°F

Circuit Breaker Testing

– Results vary with size and construction of circuit breaker • less than 100 microhms for medium voltage

– Contact resistance exposes problems not detectable with IR when there is little load current.

• Insulation Resistance – Phase to ground – Phase to phase • Functionality Tests – Close, Open – Trip

Circuit Breaker Testing Cont’d.

– Secondary Injection Testing

– Electronic CB test sets for accurate testing • Square D

• Cutler Hammer • GE

• Siemens

• New Circuit Breakers with on-board secondary injection testing • Cutler Hammer 1150 Trip Unit

Cable Testing

• New Cables

– Insulation resistance testing using hi pot at manufacturer’s recommended values

– NETA use Table 10.6 of Acceptance Testing Specs. – Leakage current should be <10 micro Amps for new cables.

• Existing Cables

– Watch out! – Be careful what voltage you use on old cables.

– Conservative approach

• RMS X Square Root of 2 = Peak voltage • Use peak value as DC value

Relay Testing

• Relays are typically used on medium voltage systems

– Older electro mechanical style relays (typical single phase) – Newer models–microprocessor based, 1 Phase + 3 Phase

– Incorporate metering and relay tripping. – Programmable on site

– Fault analysis logging for retrieval • Short Circuit and Coordination Studies

– At least 50% of facilities are not coordinated • Poor maintenance

Power Quality -

Today’s Perspective

• The quality of power 30 years ago was not much of an issue – Linear Devices

• Today many devices disrupt and corrupt the quality of the power

– Utility Side

• Voltage Sags • Impulses

• Transient Disturbances • Loss of One Phase

Power Quality – Today’s Perspective

• Switch mode power supplies (non-linear device) – Harmonic Distortion

– Overloaded neutrals – Transformer heating • SCR (non-linear device) • Loose wiring

PQ Testing

• Power Quality Analyzer – 3 phase microprocessor based analyzer that samples the voltage waveform 128 times per second. We set thresholds for voltages. By exceeding the thresholds, the machine is activated to record the “events” as they occur.

• Harmonic testing and analysis

– Measure voltage and current THD – Analyze individual harmonic values

• Engineering investigation of problem and surrounding power distribution system by power quality engineer.

Main Switchboard Voltage Sag

Vc Ic Channel Y1 Y2 Delta Channel Y1 Y2 Delta Time X1 X2 Delta Voltage 285.185 205.967 79.218 Current 277.037 200.082 76.955

Main SWBD Voltage Sag on Phase C-N

Three Phase Wye

Main SWBD Utility Capacitor

Switching Transient – Phase B-N

2.1KA 0.0A -2.1KA 500.0V 0.0V -500.0V 2.50 ms/div 0.00ns 50.00ms Impulse Disturbance Model 7100 M SWBD 12/03/01 09:48:07.93 AM

Three Phase Wye

Utility Capacitor

Switching Transient Phase B-N

2.3KA 0.0A -2.3KA 550.0V 0.0V -550.0V 2.50 ms/div 0.00ns 50.00ms Impulse Disturbance Model 7100 M SWBD 12/03/01 11:43:11.90 AM Three Phase Wye

Vb

Channel Y1 Y2 Delta

Channel Y1 Y2 Delta

Time X1 X2 Delta

Panel NEH1 Power Source

Switching Transient – Phase A-N

575.0A 0.0A -575.0A 650.0V 0.0V -650.0V 2.50 ms/div 0.00ns 50.00ms Impulse Disturbance Model 7100 Pnl NEH1 01/03/02 02:00:54.74 PM

Three Phase Wye

Panel NEH1 Power Source

Switching – Phase B-N

Three Phase Wye

Harmonic Distortion – Voltage Waveform

Harmonic Distortion - Current

How Do You Spot PQ Problems?

• Computer data errors that cannot be explained by hardware or software

• Lights flicker (not in a storm).

• Equipment power supplies have burned or damaged boards. • Transformers overheating.

• Circuit breaker nuisance tripping. • Motors overheating or failing easily.

• Voltages vary significantly from loose wiring. • Computer screens wave or are disrupted.

Power Quality and Facility

Maintenance Are Related

• Loose connections are one of the leading power quality problems

• Lack of coordination of overcurrent protection devices can cause blackouts that could have been avoided.

– Coordination Study – Short Circuit Study

• Preventative Maintenance

– Infrared thermography scan – looks for hot spots – Transformer Testing

– Oil Quality

– Dissolved Gas Analysis – Cable Testing

– Test Circuit Breakers

Conclusion

– Harsh environments

– Power Quality Problems – Need for 24/7 Reliability – Compressed schedules

• A successful 21st _{Century Facility needs four solid legs to}

stand on:

– Engineering Design – Quality Installation – Maintenance

Conclusion Cont’d.

• Excellent resources and standards from IEEE, NETA and NFPA for Testing and Maintenance

• A proper test is worth a thousand opinions. The right test equipment and experience will aid the Design Engineer in ensuring success for the Customer.