ABB REX 521 - I2> and I2

106
1MRS751802-MUM
Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
7.1.16. I2> and I2>>
The function blocks I2> and I2>> are designed for negative phase sequence
protection whenever the operating characteristic is appropriate. The function blocks
are applied in protecting power generators or synchronous motors against thermal
stress and damage
.
Fig. 7.1.16.-1 Function block symbol of I2> and I2>>
1
Includes the delay of the signal relay.
2
Includes the delay of the heavy-duty output relay.
Negative phase sequence (NPS) protection, low-set stage I2> and high-set stage I2>>
Operation mode Not in use
Definite time
Inverse time
Start value 0.01...0.50 x I
n
Operate time 0.1...120.0 s
K 5.0...100.0 s
Start delay 0.1...60.0 s
Minimum time 0.1....120.0 s
Maximum time 500...10000 s
Cooling time 5...10000 s
Number of phases 2...3
Note! The values below apply when f/fn = 0.95...1.05:
Operation accuracies ±2.5% of set value or ±0.01 x In
Start time Injected negative-sequence current = 2.00 x start value:
internal time <32 ms
total time <40 ms
1
Reset time 40...1000 ms (depending on the minimum pulse width set
for TRIP output)
Reset ratio Typical 0.96 (range 0.96...0.98) in definite-time mode
Retardation time Total retardation time when negative-sequence current
drops below the start value <45 ms
2
Operate time accuracy in definite-time mode Depends on the frequency of the current measured: ±2%
of set value or ±20 ms
2
Accuracy class index E in inverse-time mode Depends on the frequency of the current measured:
±2% of the calculated ideal operate time or ±20 ms
2
I2>
BLOCK
GROUP
RESET
START
TRIP
CBFP
BLOCK_OUT
I2>>
BLOCK
GROUP
RESET
STAR
T
TRIP
CBFP
BLOCK_OU
T