Satec Expertmeter EM720 Operation Manual page 107

Chapter 5 Configuring the EM720
Configuring Digital Triggers
Fault Indication and Cross Triggering
EM720 Power Quality and Revenue Meter
The picture above shows the factory set Fault recorder
options. Notice that the Overcurrent trigger can be used
along with the second Undervoltage trigger combined by
logical AND. If you wish to use the only Overcurrent
trigger, disable
trigger.
The Zero-Sequence Voltage trigger and the Voltage
Unbalance trigger are disabled by default. Both are very
sensitive to phase unbalances. If you want to use them,
adjust the thresholds according to your network conditions
before enabling triggers.
The Current Unbalance trigger has a different calculation
algorithm than
measurements. Since the unbalance readings give a
relation of the maximum deviation from the average to
the phase average current, the value could produce high
readings for low currents. The Current Unbalance trigger
used with the Fault recorder indicates a relation to the CT
rated current and is not sensitive to low currents.
If you use external triggering through digital inputs, you
should individually link each digital input to the Fault
recorder (see Configuring Digital Inputs
When the Fault recorder is triggered either by the fault
detector or through digital inputs, it generates a number
of specific internal events that can be monitored through
the control setpoints to give a fault indication via relay
contacts. The following describes fault events produced by
the Fault recorder:
FAULT DETECTED - the fault detector has detected a fault
event using the device's own measurements
EXTERNAL TRIGGER - the
been launched by an external trigger through one of the
digital inputs
FAULT EVENT - the Fault recorder has been launched
either by its own fault detector, or by an external trigger
These events can be found under the STATIC EVENTS
group in the setpoint trigger list (STATIC in this context
means that an event is asserted all the time while its fault
condition exists).
The FAULT DETECTED event can be effectively used for
cross triggering multiple fault recorders to simultaneously
record fault data at different locations when one of the
devices detects a fault. Each device should have a setpoint
programmed to
FAULT DETECTED event, and one digital input linked to
the Fault recorder.
Configuring Recorders
(uncheck) the second
the common
Fault
close relay
Undervoltage
current unbalance
in Chapter 5).
recorder has
contacts on the
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