Marc's Technical Pages: Power Quality Symptoms and Solutions

Contents

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DEFINITIONS
ORGANIZATIONS
SYMPTOMS
CAUSES
1. types of network connections
2. phase rotation
3. changing colours
4. issues: the main players
5. culprits
  1. the way things are done
  2. arcing
    1. natural (lightning)
    2. accidental (tracking)
    3. spurious (contact)
    4. 3364 desired (welding)
  3. 3320 motors
    1. getting started
      1. motor starts and flicker
    2. normal operation
    3. 60Hz motors @ 50Hz
    4. 3325 speed controlled
  4. technology
    1. leakage
    2. simple technology
      1. light dimmers
    3. switch mode power supplies
    4. multi-phase rectifiers (6/12 pulse)
    5. 3335 uninterrupted power supplies
      1. neutral transients and noise
  5. protection
    1. over-sensitive / nuisance tripping
    2. 'surge' & impulse arrestors
    3. 3343 incorrect protection
  6. network impedances
  7. 3380 natural causes
    1. cable capacitance
    2. AC and vibration
MEASUREMENT TECHNIQUES
1. safety
2. before we start, a word on calibrations
3. instruments in power quality:
4. using what's in the PQ bag:
5. who to consider:
  1. about the suppliers
  2. what has, and not, done the job
6. measuring aids
  1. 230V mains tester
  2. defeating socket shutters
  3. in-line monitoring adapter
  4. 'soft-earthing' instruments
  5. 4523 isolated earth spike
  6. signal isolating transformer
  7. creating a phantom neutral
  8. simple current limiter
    1. simple load bank
  9. 4570 mains noise detector for oscilloscopes
  10. measuring earth leakage and noise currents
  11. 4580 measuring busbar vibration
7. pushing the limits
  1. 4410 voltage
    1. 4411 measuring beyond 230VAC
    2. measuring in excess of 1kV
  2. the correct sized clamp
    1. current too low
    2. current too high
  3. 4450 accuracy
  4. powering from the measurement point
  5. powering from DC mains
8. course of action
  1. the 7-day rule
  2. hiring vs. buying power quality kit
9. connecting up
  1. go to pop!
  2. 4702 planning the connection
  3. 4703 the basics of current flow
  4. 4705 tracing circuits
  5. tracing matching neutrals
  6. 4710 single phase
    1. combined loads
  7. 4720 three phase
    1. 4720#1 3-phase means 3-phase
    2. 4721 direct connection (below 1kV)
    3. 4722 indirect connection (through VTs)
    4. Grounded Phase VTs ("two watt-meter method")
  8. determining flicker causes
  9. capturing high fault currents and transients
  10. testing power factor correction capacitors
  11. ground currents
    1. residual currents (single & 3-phase)
    2. 4752 ground currents and computer systems
  12. intermittent/nuisance tripping
10. programming the instrument
11. 4900 working at a distance
INTERPRETING THE READINGS
1. never dismiss a thing
2. but don't over-analyse!
3. 5100 understanding the readings
4. 5200 what to look for
  1. look to the current (VA vs W)
  2. voltage-current relationships
    1. calculating feed/line impedance
    2. 5212 determining flicker severity
    3. 5213 looking for imbalance
    4. determining load linearity
    5. leakage currents
    6. determining fault direction
  3. inrush currents
    1. flicker induced inrush
  4. harmonic content
  5. 5250 dc component
  6. resonance
  7. noise
  8. recognising signatures
  9. 5290 digging deeper
5. 5600 the lies some instruments tell
  1. mains socket testers
  2. multimeters
  3. insulation testers
  4. portable appliance testers (PATs)
  5. phase rotation meters
6. faults
  1. phase-to-phase short
  2. hi-tech load induced flicker
  3. 5312 faulty input rectifier/thyristor
7. applying specifications to readings
8. presenting the findings
SOLUTIONS
1. what's all the fuss
2. 6010 areas of responsibility
  1. preventing damage is owner's responsibility
3. "throw technology at technology" = bad idea
4. 6030 adapt scenario before employing more
  1. tripping at switch-on
5. 6100 choosing low or high impedance paths
  1. choosing high impedance paths
    1. using inductors
  2. removing the problem through isolation
    1. using common mode chokes
  3. using the simple devices supplied (ferrite cores)
6. 6200 grounds, ground loops, earth leakage
  1. 6220 remove the loop, keep the ground
    1. converting TNC-S to TNS
  2. on computer terminals
  3. 6230 in instrumentation
  4. 6240 combatting leakage induced nuisance trips
7. coping with inrush currents
  1. 6310 minor scale
    1. PFC capacitors
  2. 6320 major scale
8. 6400 waveform impurity correction
  1. 6410 hi-tech power supplies
  2. active harmonic filters
  3. combatting noise
9. from spikes to momentary swells & sags
  1. we cannot stop lightning
  2. reasons for installing impulse protection
  3. surge & impulse protection solutions
    1. a modular surge protection system
    2. individual appliance surge protection
    3. 6533 across independent grounds/earths
  4. 6540 dealing with momentary voltage dips/sags
  5. 6550 dealing with momentary voltage swells/surges
  6. 6551 dealing with long-term voltage swells/surges
10. sustained low/high voltage
  1. auto-transformers
11. 6900 some novel ideas
  1. A SuperCap UPS
A FEW MYTHS
"I'm STUCK"
"Other Resources"

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