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CHAPTER 6: SETPOINTS
Negative sequence overvoltage
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
The relay has one Negative Sequence Overvoltage element. The negative sequence
overvoltage may be used to detect the loss of one, or two phases of the source, a reversed
voltage phase sequence, or non-system voltage conditions.
The following path is available using the keypad. For instructions on how to use the
keypad, please refer to Chapter 3 - Working with the Keypad.
PATH:
SETPOINTS > S3 PROTECTION > NEGATIVE SEQ OV
NEG SEQ OV FUNCTN
Range: Disabled, Alarm, Latched Alarm, Trip
Default: Disabled
The selection of the Latched Alarm, Alarm, or Trip setting enables the Negative
Sequence OV function. The output relay #1 "Trip" will operate, if the function is selected
as a Trip and the negative sequence voltage computed by the relay is above the NEG
SEQ OV PKP setting for a time greater than the selected NEG SEQ OV DELAY time. The
"ALARM" LED will not turn on if the neg. sequence OV function is set to Trip. The "ALARM"
LED will flash upon an OV operating condition with the neg. sequence OV function
selected as Alarm, and will self-reset, when the operating condition clears. If Latched
Alarm is selected as a Neg. Seq. OV function, the "ALARM" LED will flash during the OV
condition, and will stay "ON" after the condition clears, until the reset command is
initiated. The output relay #1 "Trip" will not operate if the Latched Alarm or Alarm
setting is selected. Any or all of the output relays 3 to 6 can be selected to operate when
the NEG SEQ OV FUNCTN is selected as Latched Alarm, Alarm, or Trip.
NEG SEQ OV PKP
Range: 0.00 to 1.25 x VT in steps of 0.01
Default: 0.30 x VT
This setting defines the negative sequence OV pickup level.
NEG SEQ OV DELAY
Range: 0.1 to 600.0 sec in steps of 0.1 sec
Default: 2.0 s
This setting specifies the time delay before negative sequence OV operation.
OUTPUT RELAY 4 to 6 / OUTPUT RELAY 5 to 6
Range: Do not operate, Operate
Default: Do not operate
Any assignable output relay can be selected to operate upon Negative Sequence
Overvoltage operation. When the SWITCHING DEVICE is selected as BREAKER, the
assignable output relays will be Output Relay 4 to 6. When the SWITCHING DEVICE is
selected as CONTACTOR, the assignable output relays will be Output Relay 5 to 6.
BLOCK 1/2/3
Range: Off, Contact Input 1 to 10, Virtual Input 1 to 32, Remote Input 1 to 32, Logic
Element 1 to 16
Default: Off
Three blocking inputs are provided for Negative Sequence Overvoltage. When any of the
selected blocking inputs is on, the NEG SEQ OV function is blocked. The available
selections for each block can be any Contact input, Virtual Input, Remote Input, or Logic
Element.
S3 PROTECTION
6–105
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