Voltage Restrained Overcurrent - GE Multilin 489 Instruction Manual

7.3.10 Voltage Restrained Overcurrent Accuracy
7–20
Courtesy of NationalSwitchgear.com
Setup the relay as shown in FIGURE 7–3: Secondary Injection Test Setup #3 on page 7–19.
In the
S2 SYSTEM SETUP
GENERATOR RATED MVA:
GENERATOR VOLTAGE PHASE-PHASE:
In the
S2 SYSTEM SETUP
VT CONNECTION TYPE:
VOLTAGE TRANSFORMER RATIO:
In the
S5 CURRENT ELEMENTS
OVERCURRENT ALARM:
O/C ALARM LEVEL:
OVERCURRENT ALARM DELAY:
O/C ALARM EVENTS:
In the
S5 CURRENT ELEMENTS
PHASE OVERCURRENT TRIP:
ENABLE VOLTAGE RESTRAINT:
PHASE O/C PICKUP:
CURVE SHAPE:
O/C CURVE MULTIPLIER:
O/C CURVE RESET:
The trip time for the extremely inverse ANSI curve is given as:
⎛
⎜
A
+
Time to Trip M × ⎜
=
⎜
⎝
where:M =
O/C CURVE MULTIPLIER
I = input current
I =
PHASE O/C PICKUP
p
A, B, C, D, E = curve constants, where A = 0.0399, B = 0.2294, C = 0.5000, D = 3.0094,
and E = 0.7222
K = voltage restrained multiplier <optional>
The voltage restrained multiplier is calculated as:
K
-------------------------------------------------------------------------- -
=
rated phase-to-phase voltage
and has a range of 0.1 to 0.9.
Using Secondary Injection Test Setup #3 on page 7–19, inject current
and apply voltage as per the table below.
Verify the alarm/trip elements and view the event records in the
EVENT RECORD
GEN. PARAMETERS
"100 MVA"
VOLTAGE SENSING
"Open Delta"
"100:1"
OVERCURRENT ALARM
"Unlatched"
"1.10 x FLA"
"2 s"
"On"
PHASE OVERCURRENT
"Latched"
"Yes"
"1.5 x CT"
"ANSI Extremely Inv."
"2.00"
"Instantaneous"
B D
---------------------------- - ------------------------------------ -
+
I 2
I
⎛ ⎞
------------------ - C
------------------ - C
–
–
⎝ ⎠
K 〈 〉 ×
I
K 〈 〉
× I
p
p
setpoint
setpoint
phase-to-phase voltage
menu.
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 7: TESTING
menu, set:
"12000"
menu, set:
menu, set:
menu, set:
⎞
E
⎟
------------------------------------ -
+
⎟
3 (EQ 7.8)
I
⎛ ⎞
------------------ - C
⎟
–
⎝ ⎠
K 〈 〉
× I
⎠
p
(EQ 7.9)
A5