ABB REF610 - Operate Time Tolerances Specified by the Standard

inverse characteristic, the normal current range is specified to be 2...7 times the set
pickup value, and the relay is to start before the current exceeds the set pickup value
by 1.1 times
Table 5.1.4.9.-3 Operate time tolerances speci fied by the standard
M
a)
Normal
b)
Very
b)
Extremely
b)
Long time
b)
2 2.22E 2.34E 2.44E 2.34E
5 1.13E 1.26E 1.48E 1.26E
7 - - - 1.00E
10 1.01E 1.01E 1.02E -
20 1.00E 1.00E 1.00E -
a)
Multiples or pickup current (a phase and ground)
b)
E = accuracy in percent; - = not specified
Within the normal current range the inverse-time element fulfills the tolerance
requirements of class 5 or ±25 ms at all degrees of inversity.
The time/current curve groups based on the IEC standard are illustrated in
Fig. 5.1.4.9.-1...Fig. 5.1.4.9.-4.
If the ratio between the current and the set pickup value is higher than
20, the operate time is the same as when the ratio is 20.
46
REF610REF610
Feeder Protection Relay
Technical Reference Manual - ANSI Version
1MRS755535