Switches - GE 889 Instruction Manual

SYSTEM

Switches

4–88
The Single Line Diagram (SLD) from the 8 Series relays can be configured with up to 9
disconnect switches. The disconnect switch detection is performed by monitoring the
state/states of either one or preferably two contact inputs 89a and 89b. Monitoring the
status of the switch using both auxiliary contacts 89a, and 89b is recommended, however
using only one of them is also possible.When both contacts are programmed, the switch
can be monitored for state discrepancy, i.e. both auxiliary contacts OFF, or both auxiliary
contacts ON during operation. Discrepancy Alarm Delay can be programmed to reflect the
transition of the switch during operation from Closed to Opened, and Opened to Closed. If
no auxiliary contact discrepancy is detected after the time delay expires, the switch will be
in one of its normal states, i.e. Opened or Closed. However, if contact inputs discrepancy is
detected after the time delay expires, the relay will issue a "SW1(9) Discrepancy" target
message and illuminate the ALARM LED. The switch discrepancy condition can be reset by
the operand assigned under Reset Alarm setpoint, providing both contact inputs 89a and
89b show normal states on the relay.
Path:
Setpoints > System > Switches > Switch 1(9)
NAME
Range: 13 alphanumeric characters
Default: SW 1
Assign a user-defined name to the disconnect switch. This name is used in the SLD, flash
messages related to disconnect switch 1, and the event recorder.
CONTACT INPUT 89a
Range: Off, Any FlexLogic operand
Default: Off
Select an operand (usually NO aux. contact wired to contact input in the relay) to reflect
the status of the Disconnect Switch auxiliary contact 89a.
CONTACT INPUT 89b
Range: Off, Any FlexLogic operand
Default: Off
Select an operand (usually NC auxiliary contact wired to contact input in the relay) to
reflect the status of the Disconnect Switch auxiliary contact 89b.
ALARM DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 2.000 s
This setting specifies the required time interval to overcome transient disagreement
between the 89a and 89b auxiliary contacts during disconnect switch operation. If
transient disagreement still exists after this time has expired, SW1(9) Discrepancy
FlexLogic operand is asserted for alarm and/or blocking purposes.
RESET ALARM
Range: Off, Any FlexLogic operand
Default: Off
Select an operand from the list of FlexLogic operands, which when asserted resets the
Switch Discrepancy state. Please note that resetting the discrepancy alarm will work
only after no discrepancy condition exists between the switch aux contacts 89a and
89b.
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS