User's Manual

ANSI Electric Meter v3.1 User’s Guide 55
Power Threshold on Exhausted Credit
This is the active power level setting, in watts, at which the load disconnect turns off
when prepay credit is exhausted (goes to 0). The Maximum Power Duration
Threshold setting also affects this feature.
Load Disconnect Re-Synchronization
In some situations, the internal state of the load disconnect contactor (meaning the
desired status of the load disconnect contactor as requested by NES System Software
or the meter program) may not match the actual physical state of the load disconnect
contactor. When this occurs, the meter may attempt to re-synchronize
by changing the physical state of the load disconnect contactor to match the internal
state. A Load Disconnect State Changed alarm will be reported if the
resynchronization attempt succeeds, and a Disconnect Switch Error alarm is
reported if it fails.
You should be aware that re-synchronizations will only be attempted if the load
disconnect contactor was synchronized properly before the error occurred, and no
Disconnect Switch Error alarm has yet been logged for this condition (meaning that
multiple re-synchronizations will not be attempted for the same error condition).
If the meter is not able to determine the physical state of the load disconnect
contactor and this condition persists for at least 2.5 seconds, then the meter logs a
Disconnect Switch Error alarm and no re-synchronization will be attempted. Some
examples of when this can occur are:

The load disconnect contactor is open, and there is load side
generation. Note that you can configure the meter to trigger the Load
Side Voltage Detected alarm when load side voltage is detected.
 The meter is not wired correctly.
 The link is open and the measured instantaneous power level is non-
zero or the sensor on the load disconnect contactor indicates closed.
 Some form of hardware error has occurred.
Resynchronization can be configured to be always enabled, always disabled or
enabled only once the meter has been commissioned. The latter is recommended as it
avoids anomalous behavior when the meter is used in pre-installation lab situations
where the link is open.
Generally, the disconnect switch is not resynchronized when the meter powers up. If
an out-of-sync condition is detected when the meter powers up, the state of the load
disconnect contactor will be left as it is (meaning that it will be closed if it was closed
before it powered down, or open if it was open before it powered down).
Note: If voltage will be applied variably to the load conductors with the test voltage
link open, then it must not be not applied initially (for several seconds) after
the meter powers up to ensure that the meter has effectively disabled
resynchronization attempts.
However, if the state of the load disconnect contactor is changing as the meter
powers down, then the meter will resynchronize the internal state of the load
disconnect contactor so that it matches the current physical state when it powers
back on. A Load Disconnect State Change will be logged, as well as a Disconnect
Switch Error event (argument format 1) in this case.