GE Multilin 489 Instruction Manual page 267

CHAPTER 7: TESTING
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
Minimum Pickup Check
Connect the relay test set to inject Channel X current (I
terminal and out of H3 terminal (Phase A). Increase I
differential element picks up.
Record this value as pickup.
Switch off the current.
The theoretical pickup can be computed as follows:
I
XPU
Single Infeed Fault
Set the I
Set the fault current equal to CT.
Apply the fault.
Switch off the current.
Record the operating time.
Set the I
Set the fault current equal to 5 × CT.
Apply the fault.
Switch off the current.
Record the operating time.
Slope 1 Check
Connect the relay test set to inject Channel Y current (I
terminal and out of H6 terminal.
The angle between I
Set pre-fault current, I
Set fault current, I
At this value the relay should operate according to the following formula:
I
=
XOP1
Set fault current, I
Apply the fault.
The relay should operate.
Switch off the current.
Set fault current, I
Apply the fault.
The relay should restrain.
Switch off the current.
×
Pickup setting CT
=
prefault current equal to 0.
x
prefault current equal to 0.
x
and I will be 180°.
x Y
and I equal to zero.
x Y
equal to 1½ CT.
Y
2 Slope 1 setting 3 CT ×
–
--------------------------------------------- - × ---------------
2 Slope 1 setting 2
+
equal to 0.95 × I
x XOP1
equal to 1.05 × I
x XOP1
) into the G3
x
until the
x
(EQ 7.5)
) into the G6
Y
(EQ 7.6)
.
.
7–17