Auxiliary Overvoltage Protection - GE 845 Instruction Manual

CHAPTER 4: SETPOINTS
Auxiliary Overvoltage
Protection
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
The 845 relay provides one Auxiliary Overvoltage (OV) element per protection group, or a
total of 6 elements. Each Auxiliary OV element is used to protect voltage sensitive loads
and system components against sustained overvoltage conditions. This element can be
used for monitoring zero-sequence voltage (from an "open corner delta" VT connection),
permissive functions, source transfer schemes, restoration and similar functions.The
Auxiliary OV element can be set as an instantaneous element with no time delay or may be
set as a definite time element. The input voltage is the auxiliary voltage.
The settings of the Auxiliary OV Protection function are applied to the auxiliary voltage
input to produce pickup and trip flags. The Auxiliary OV pickup flag is asserted, when the
voltage on auxiliary input is above the PKP value. The Auxiliary OV trip flag is asserted if the
element stays picked up for the time defined by pickup time delay. The element drops from
pickup without operation, if the measured voltage drops below 97-98% of the pickup value
before the time for operation is reached.
Path:
Setpoints > Protection > Group 1(6) > Voltage > Auxiliary OV
FUNCTION
Range: Disabled, Trip, Alarm, Latched Alarm, Configurable
Default: Disabled
PICKUP
Range: 0.00 to 3.00 x VT in steps of 0.01 x VT
Default: 1.50 x VT
This setting sets the auxiliary overvoltage pickup level specified per times VT.
For example, a Pickup setting of 1.10 x VT with 13800:115 VT translates into 15.08kV (or
126.5V secondary).
PICKUP DELAY
Range: 0.000 - 6000.000s in steps of 0.001s
Default: 1.000s
DROPOUT DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 1.000 s
BLOCK
Range: Off, Any operand from the list of FlexLogic operands
Default: Off
RELAYS
Range: Do Not Operate, Operate
Default: Do Not Operate
PROTECTION
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