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345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
S3 PROTECTION
CHAPTER 6: SETPOINTS
Phase instantaneous
overcurrent
protection
The 345 relay has two identical instantaneous overcurrent protections - Phase IOC1, and
Phase IOC2 per protection group. Each of them consists of three separate instantaneous
overcurrent relays; one per phase, with identical settings. .
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 > S3 SETPOINT GROUP 1(2) > S3 PHASE IOC1(2)
PH IOC1(2) FUNCTION
Range: Disabled, Latched Alarm, Alarm, Trip
Default: Disabled
The selection of the
Latched Alarm
,
Alarm
, or
Trip
setting enables the Phase IOC
function. The output relay #1 “Trip” will operate when the
Trip
setting is selected, and the
Phase IOC is operational. The “ALARM” LED will not turn on if the IOC is operational when
set to the
Trip
function. The “ALARM” LED will flash upon phase IOC operation, and with
the IOC function selected as
Alarm
, will self-reset when the operation clears. Until the
Reset command is initiated, if
Latched Alarm
is selected, the “ALARM” LED will flash
during IOC operation, and will stay “ON” after the operation clears. Output relay #1 “Trip”
will not operate if the
Latched Alarm
or
Alarm
function is selected.
PH CT INPUTS
Range: CT(W1), CT(W2)
Default: CT(W1)
The Phase Instantaneous Overcurrent menu provides a selection for either CT(W1) input
currents or CT(W2) currents. If CT(W1) is selected, the PH IOC element will use the ratings
of the Winding 1 CTs entered on the relay under SYSTEM SETUP/S2 CURRENT SENSING. If
the CT(W2) setting is selected, the relay will use the CT ratings associated with
transformer Winding 2.
PH IOC1(2) PKP
Range: 0.05 to 20.00 x CT in steps of 0.01 x CT
Default: 1.00 x CT
This setting sets the instantaneous overcurrent pickup level. For example, a PKP setting
of 0.9 x CT with 300:5 CT translates into 270A primary current.
PH IOC1(2) DELAY
Range: 0.00 to 300.00 sec in steps of 0.01 sec
Default: 0.00 sec
This setting provides selection for the time delay used to delay the protection operation.
RLY1 TRIP W1 BKR and RLY2 TRIP W2 BKR
Range: Do not operate, Operate
Default: Do not operate
The menu for the two trip output relays - RLY1 TRIP W1 BKR and RLY2 TRIP W2 BKR - is
available only if the
Trip
setting is selected as the function for the Phase Instantaneous
Overcurrent element. One or both trip output relays can be selected to operate upon
Phase IOC operation.
NOTE
NOTE:
The "RLY1 TRIP W1 BKR" and "RLY2 TRIP W2 BKR" setpoints will be displayed on the OC
menu regardless of the selected OC function. These output relays will not operate if
either
Alarm
or
Latched Alarm
is selected as an OC function, regardless of the Operate/
Do Not Operate value selected. The output relays are operational only if the OC function
is selected as
Trip
.