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1 PRODUCT DESCRIPTION
Within the LPS-D, the DC battery voltage across each of the open trip contacts (or SCRs) may be continuously
monitored to determine if the associated trip circuit is intact. If the monitored DC voltage drops to zero, then the
trip circuit has failed to open, or the breaker 52/a contact, which is normally wired in series with the trip coil, has
opened. This function is intended to replace the red light indicator typically used for trip-circuit monitoring, and
it can be selectively disabled for each breaker.
There are four trip contacts (or SCRs) in the LPS-D. The voltage across each contact (or SCR) is monitored
separately. Any combination of trip circuits may be monitored by General Setting 107: NUM_MON.
Operation of the Trip Circuit Monitor causes a noncritical alarm event. If one or more breaker poles are opened
in some manner other than by a trip issued by the LPS-D, then the 52/a contact normally wired in series with
the trip coil opens and drops the voltage across the open contact to zero. To avoid a noncritical alarm for this
condition, closure of the associated 52/b contact disables the Trip Circuit Monitor function for the involved pole.
Two separate alarms are provided. The output relays associated with these alarms are not user programma-
ble. Both of these alarms have form C contacts and are energized under normal conditions.
•
The critical alarm de-energizes when the relay self-test logic detects a problem that warrants taking the
relay system out of service.
The power supply alarm de-energizes when the power supply fails or is turned off.
•
A user programmable non-critical alarm is also provided. Operation of the non-critical alarm will cause an
event to be logged, and may be programmed to a user-assigned output contact. The non-critical alarm is de-
energized in normal conditions. The default inputs to the non-critical alarm include the following conditions:
1. Trip Circuit Alarm
2. Zone Flags On Alarm
3. Overcurrent Alarm
4. Unbalance Current Alarm Detector
Additional inputs, such as line over load alarm, may be added by the user via Xpression Builder.
Metering values may be obtained by using the keypad, or through remote communications. The following
quantities are available: RMS voltage and current, phasor voltage and current, Watts, Vars, Power Factor, sys-
tem frequency, and Breaker health. The voltage and current values are accurate to 1% of reading. Refer to
Chapter 8.1.3: CONTROL KEYS on page 8–2 for a description on how to use the metering function.
Two different breakers may be selectively tripped or closed via the local keypad or a remote PC connected to
the RS232 port. The commands are as follows:
•
Trip Breaker 1 and Trip Breaker 2 use the same output contacts or SCRs as a fault trip command.
•
Close Breaker 1 and Close Breaker 2 use separate auxiliary relays. The contact of each auxiliary relay
must be wired to the appropriate breaker's close circuit.
Remote breaker tripping and closing are enabled or disabled with a jumper on the Processor module as shown
in Figure 3–5: INPUT BOARD DIAGRAM on page 3–7. The LPS-D is shipped from the factory with this jumper
removed and Breaker Control enabled. Install the jumper to disable Remote Breaker Control.
GE Power Management
LPS-D Line Protection System
1.5 OTHER FEATURES
1.5.13 TRIP CIRCUIT MONITOR
1.5.14 ALARMS
1.5.15 METERING
1.5.16 BREAKER CONTROL
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