Relay Assignment Practices - GE Multilin 489 Instruction Manual

CHAPTER 5: SETPOINTS
5.1.3

Relay Assignment Practices

489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
Note that a lockout time will occur due to overload trip (see Model Setup on page 5–71 for
additional details).
Alarms
A 489 alarm feature may be assigned to operate any combination of four output relays:
2 Auxiliary, 3 Auxiliary, 4 Auxiliary, and 5 Alarm. When an alarm becomes active, the
appropriate LED (indicator) on the 489 faceplate will illuminate when an output relay(s) has
operated. Each alarm feature may be programmed as latched or unlatched. Once a
latched alarm feature becomes active, the reset key must be pressed to reset that alarm. If
the condition that has caused the alarm is still present (for example, hot RTD) the Alarm
relay(s) will not reset until the condition is no longer present. If on the other hand, an
unlatched alarm feature becomes active, that alarm will reset itself (and associated output
relay(s)) as soon as the condition that caused the alarm ceases. As soon as an alarm
occurs, the alarms messages are updated to reflect the alarm and the 489 display defaults
to that message. Since it may not be desirable to log all alarms as events, each alarm
feature may be programmed to log as an event or not. If an alarm is programmed to log as
an event, when it becomes active, it is automatically logged as a date and time stamped
event.
Control
A 489 control feature may be assigned to operate any combination of five output relays:
1 Trip, 2 Auxiliary, 3 Auxiliary, 4 Auxiliary, and 5 Alarm. The combination of relays available
for each function is determined by the suitability of each relay for that particular function.
The appropriate LED (indicator) on the 489 faceplate will illuminate when an output relay(s)
has been operated by a control function. Since it may not be desirable to log all control
function as events, each control feature may be programmed to log as an event or not. If a
control feature is programmed to log as an event, each control relay event is automatically
logged with a date and time stamp.
There are six output relays. Five of the relays are always non-failsafe, the other (Service) is
failsafe and dedicated to annunciate internal 489 faults (these faults include setpoint
corruption, failed hardware components, loss of control power, etc.). The five remaining
relays may be programmed for different types of features depending on what is required.
One of the relays, 1 Trip, is intended to be used as a trip relay wired to the unit trip breaker.
Another relay, 5 Alarm, is intended to be used as the main alarm relay. The three remaining
relays, 2 Auxiliary, 3 Auxiliary, and 4 Auxiliary, are intended for special requirements.
When assigning features to relays 2, 3, and 4, it is a good idea to decide early on what is
required since features that may be assigned may conflict. For example, if relay 2 is to be
dedicated as a relay for sequential tripping, it cannot also be used to annunciate a specific
alarm condition.
In order to ensure that conflicts in relay assignments do not occur, several precautions
have been taken. All trips default to the 1 Trip output relay and all alarms default to the
5 Alarm relay. It is recommended that relay assignments be reviewed once all the setpoints
have been programmed.
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