MOL · capability 07 of 08
Wiring faults that leave a meter reading plausibly.
If two current phases are swapped, a CT (current transformer) polarity is reversed or a voltage connection is crossed, the meter still displays plausible voltages and currents. Active power, reactive power and power factor are all wrong, but nothing on the bill looks unusual enough to query. Faults of this kind run for years without being noticed.
Power information
| Red | White | Blue | Total | |
|---|---|---|---|---|
| P (W) | 491.29 | 117.57 | 108.14 | 717.00 |
| Q (var) | 253.90 | 275.23 | 182.35 | 711.48 |
| S (VA) | 553.02 | 299.29 | 212.00 | 1010.09 |
| PF | 0.89 Ind | 0.39 Ind | 0.51 Ind | 0.71 Ind |
Voltages and currents
| Red | White | Blue | |
|---|---|---|---|
| Voltage | 231.10 V | 234.00 V | 234.00 V |
| V-angle | 0.00° | 239.00° | 120.00° |
| Current | 2.39 A | 1.28 A | 0.91 A |
| I-angle | 332.67° | 172.13° | 60.67° |
3-Phase 4-Wire. Voltage and current are drawn to separate scales: voltage as thin lines, current as heavy lines.
A phasor snapshot is stored with every reading.
MOL captures a phasor snapshot each time it reads a meter: the magnitude and angle of every voltage and current. Plotted, a correct installation has a shape an engineer recognises immediately, and an incorrect one does not.
A reversed CT places a current almost 180 degrees from its correct position. A swapped phase pair changes the phase sequence. Neither fault shows in the energy register, which is why both can remain undetected for a long time.
The snapshot is stored with the reading, so if a bill is challenged there is evidence of how the meter was connected at the time.
Meters record events as well as consumption.
A modern meter keeps an event log of covers opened, phases lost, clock adjustments and attempts to interfere with the meter. On most installations the log is never read, because reading it requires a site visit.
MOL collects the event log with the readings and reports significant events as they occur, instead of leaving them to be found during a later investigation.
- Tamper
- Cover removal, terminal cover, magnetic interference, reverse energy where no generation exists.
- Supply
- Phase loss, phase failure, over- and under-voltage, voltage imbalance.
- Metering
- Clock drift and reset, programming change, demand reset, register rollover.
- Communications
- Failure to respond, repeated retries, or a meter that has stopped reporting entirely.
PMT's last-gasp gateways report a loss of supply as it happens.
PMT's last-gasp gateways send a message as the power fails, reporting that supply has been lost. When enough gateways report at once, the topology model narrows the report from a list of customers without supply to the highest point in the network where the fault could be.
The crew is directed to a transformer rather than to the address of the first customer who called.
Notification before customers call
Notification comes from the last-gasp gateways, not from customers. On a large-power-user estate the first call often comes long after the trip.
Restoration confirmed by the meters
Meters report when supply returns, so a job is closed on evidence rather than on the crew's assumption that supply is back.
Timestamped outage records
Start, extent and restoration are timestamped from the network itself. Interruption reporting requires this, and a spreadsheet cannot provide it.
See this applied to your own data.
PMT will run it against a month of your readings and show you the results.