Understanding Power Quality Monitoring

1. Understanding Power Quality Monitoring Basics of Power Quality Monitoring

2. Objectives • What is Power Quality and how do we determine Methods of test. • Describe the nature of several different types of power-related problems. • Describe the methods for testing for the different types of problems. Basics of Power Quality Monitoring

3. What is Power Quality Except for complete failure, most really don’t pay close attention to the power we are supplied. With the emergence of the “Electronics Age” there has be a change in the requirement of our electrical distribution systems. Unlike traditional load, like lighting or motors, Sensitive loads are more susceptible to power disturbances. Electronic equipment requires a much more stable power source. Basics of Power Quality Monitoring

4. Importance of Power Quality • Consequences of poor Power Quality can result in: • Lost productivity • Lost/corrupt data • Damaged equipment • Poor power efficiency • U.S. companies waste an estimated $26 billion on electrical power-related issues each year* *Electrical Contractor Magazine, “Surveying Power Quality Options” March 2000 Basics of Power Quality Monitoring

5. Power Quality • There is no absolute definition of power quality, but many define it as the degree to which both the utilization and the performance of electric power affects the performance of an electrical distribution system. • Organizations such as the IEEE -Institute of Electrical and Electronics Engineer and ANSI -American National Standards Institute are setting Stringent requirements for power Quality. • IEEE 519-81 Recommended limits on Harmonics • ANSI C84.1 Specification on normal voltage ratings and tolerances Basics of Power Quality Monitoring

6. Power Quality • Power and Power Factor • Measure of how efficiently Power is used • Disturbances • Momentary disruptions to the Electrical system • Harmonics • Integers of the Fundamental Frequency which have an effect on the electrical systems and loads Basics of Power Quality Monitoring

7. Power Quality Power And Power Factor • Power is measured in KW or Kilowatts • Kilowatt is defined as Volts x Amps x Cos Φ • Φ is the phase angle difference between the Voltage and current. Most utilities have an additional charge if PF is less than .95 to .90 Basics of Power Quality Monitoring

8. Power Quality Disturbances • The NIST -National Institute of Standards and Technology shows that disturbances can be defined in two categories, • Steady State or Intermittent. • Steady state disturbances are Noise, Harmonics, long term Over-voltage or Under-voltage conditions. • Intermittent disturbances are Sages, Swells, Impulse, Transients, and interruption, Basics of Power Quality Monitoring

9. Power Quality Power disturbances • Voltage Sags and Swells • Under-voltage or Over-voltage • Transients spikes, impulses and surges • Outages • Harmonics • Noise Basics of Power Quality Monitoring

10. Power Quality • Voltage Sag • Momentary decrease in line Voltage • Caused by the start of heavy loads or fault occurrence on source. • Voltage Swells • Momentary increase in line Voltage • Occurs due to sudden load decrease or de-energizing of heavy equipment. Basics of Power Quality Monitoring

11. Power Quality • Over-Voltage • Abnormally high voltage • Power voltage regulation • Under-Voltage • Abnormally low Voltage • Result for clearing of a fault or intentional utility regulation. Basics of Power Quality Monitoring

12. Power Quality • Impulse (Transients): • Short duration high amplitude pulses are surges that are superimposed on a normal voltage waveform. • Vary widely from twice the normal voltage to several thousand volts in time from < microsecond to a few hundreds of a second. • Result for loads cycling on and off in a building, utility, or lighting Basics of Power Quality Monitoring

13. Power Quality • Outages • Outage is a complete loss of power lasting from a few milliseconds to several hours. • Caused by power system failure due to damage to supply lines or equipment failure Basics of Power Quality Monitoring

14. Power Quality • NOISE: is an unwanted signal or distortion that is superimposed on a normal voltage waveform • Normal Mode noise • Common Mode noise • RFI: Radio Frequency interference • EMI: Electromagnetic interference Basics of Power Quality Monitoring

15. Power Quality Harmonics • Harmonics are multiple of the fundamental frequency • For us in the USA this is 60 Hz • Harmonics in our electrical systems are normally caused by distortion of either our Voltage or Current waveform • Major cause of harmonics is electronic loads that draw there currents in short pulses. Basics of Power Quality Monitoring

16. Power Quality Harmonics • Non-Linear loads • Computers, printer, copiers, electronics lighting • Adjustable speed drives and other microprocessor controlled equipment • Effects on electrical systems or odd harmonics 3rd, 5th, 7th etc. Basics of Power Quality Monitoring

17. Harmonics Harmonics • Total Harmonic Distortion • Expressed as %THD • Percentage of distortion to the sine wave • Should not exceed 5% of line voltage or 20% of current • Harmonic FFT’s • Breakdown of the THD to the individual harmonics • Show the amount of harmonic as a percentage of the fundamental. Knowing each harmonic and its effect can help in determines the impact on the system Basics of Power Quality Monitoring

18. Power Quality- Standards ITIC (CBEMA) Curve • ITIC, Information Technology Industry Council is just one of may professional or governing agency that have adopted acceptable tolerance for power delivered to our sensitive electronic equipment. Basics of Power Quality Monitoring

19. Plan, Investigate & Test • Where to start • Plan your site survey • Investigate suspected areas • Test or monitor • Analyze results or date Basics of Power Quality Monitoring

20. Plan Make a block diagram of you facility. Basics of Power Quality Monitoring

21. Investigate • Investigate suspected areas • Try to establish time of occurrence and duration history • Equipment usage cycles or new equipment instillation • Personnel • Interview others- Find out what they have observed Basics of Power Quality Monitoring

22. Test • Power and Power Factor, Inductive or Capacitive reactance, or how efficient we use the power that is delivered. • A Power Analyzer is the tool of choose when the measurement of Power usage are efficiency is desired. • Disturbances, like Sage Swell and Impulse are normally generated within a facility and affecting our sensitive electronics equipment • In the pass Power analyzers my have been used at a main or sub-panel, but were not cost effective for branch circuit monitoring. • Today, however we have a small inexpensive tools that can be plug at the device or equipment that is being effected. Basics of Power Quality Monitoring

23. Testing • Most power quality failures may be tracked down to one of three areas. • Supply- Utilities and its distribution. • Internal Distribution- Feeders and Branches, Grounding, wiring and termination • Internal Loads- load disturbances and Harmonics Basics of Power Quality Monitoring

24. Testing Supply – Utilities Disturbance • Supply Disturbances and service area • Utility faults, • switching transients, regulation • Lighting, • Transients, outages • Accidents to Transmission lines • outages • Failure of backup sources • Outage, under of over voltages Basics of Power Quality Monitoring

25. Testing Internal Disturbances • Many studies have been conducted and found that 80% of power Quality problems are generated within a facility • Of this, 80% of those are related to inadequate wiring or poor grounding. • Power and Power reactance. • Line to Neutral Voltage • Sags& Swells, under-voltage & over-voltage, Impulse, Distortion. • Neutral to Ground Voltage • High resistance grounds, Load imbalance, Harmonics Basics of Power Quality Monitoring

26. Testing • A Hospital is wanting to add new diagnostic equipment. • Before the equipment is added to the service they need to determine if the present system can handle the additional load. Basics of Power Quality Monitoring

27. Testing • This is an example of data taking at a hospital in North Carolina. Two observation can be made from this data. • First, is a drop in Voltage during Wednesday, not seen in any other days data. Why? • Second, is a load imbalance, where phase 2 and 3 are drawing around 40 amps more that phase 1 Basics of Power Quality Monitoring

28. Testing • When we look at the Power of each phase we can also see that Phase 1 average is 4000 Watts less that phase 2 and 3. Both phase 2 and 3 average in the range of 7000 Watts. Basics of Power Quality Monitoring

29. Testing Branch Circuits • Line to Neutral Voltage • Transients, Sags& Swells, Voltage drops, Flat toping • Neutral to Ground Voltage • Tripling harmonics, High ground impedance. Basics of Power Quality Monitoring

30. Testing Branch Circuits • Voltage Distortioncan be caused by large harmonic currents from Nonlinear loads or Power sources with no sinusoidal Voltage Characteristic • Linear loads have small effects on voltage distortion. • Non-Linear loads have a larger effect on voltage distortion Excessive Current drawn as the Voltage waveform reaches Peak can cause Voltage distortion. Referred to as Flat Topping or Clipping. Basics of Power Quality Monitoring

31. Testing Branch Circuits • Major loads affected • Computers • Copiers, Laser printers, and other Large office loads • HVAC Equipment • Industrial equipment, Like ASD’s (Adjustable Speed Drives) • Lighting • UPS systems Basics of Power Quality Monitoring

32. Testing • Key Points for comparison • Only important evens are logged • Events are sorted by Time (log) • Events are sorted by Type (event) • Waveform shape is measured for THD Basics of Power Quality Monitoring

33. Testing Events Log? • Sag – low voltage for brief periods (dips) • Swell- high voltage for brief periods (surges) • Voltage Transient- impulses (spikes) • THD for Total Harmonic Distortion (noise) Basics of Power Quality Monitoring

34. Testing What cause the event and When ? • Amplitude of the event • Number of Cycles (duration) • Time of event • Date of event Basics of Power Quality Monitoring

35. Test Equipment • Test or Monitor , Basic measurement tools • Circuit Analyzer • Multimeter or ClampMeters • (True RMS responded) • Receptacle Event Recorder • Power Quality Monitor. • Infrared temperature device Always follow proper Safety precautions Lock-out Tag-out, safety gear like glasses and gloves Basics of Power Quality Monitoring

36. Test Equipment • Most equipment, like circuit Analyzers, meters and clamps are slow responding. • They sample at speeds around 2 or 3 times a second. • OK for steady state problems • To slow for intermittent disturbances. • Intermittent disturbances require equipment which samples at a number of samples per cycle. Basics of Power Quality Monitoring

37. Test Equipment • 160 Series SureTest Circuit Analyzers • 830 Voltage Performance Monitor • 800 Series Power Analyzer Basics of Power Quality Monitoring

38. SureTest Circuit Analyzers • Circuit Analysis • Measures voltage drop under full 15 Amp load, • Neutral to Ground Voltage • Ground Impedance • Hot and Neutral Conductor Impedance. Basics of Power Quality Monitoring

39. 830 Voltage Performance Monitor • 830 Voltage Performance Monitor is great for evaluation clean Power on a branch circuits. • Sag • Swells • Impulses • %THD • Depth and duration of each event is log with time and date stamp • The powerful box with the Power Quality Engineer inside Basics of Power Quality Monitoring

40. 800 Series Power Analyzer • Power measurements • kW, Power Factor, kVA, kVAR • Harmonic measurements • %THD, harmonic factorization to 51st harmonic • Disturbances • Capture level 2 transients (0.5µs) Basics of Power Quality Monitoring