Operate Time Tolerances Specified By The Standard - ABB REF610 Technical Reference Manual

REF610 REF610
46
Feeder Protection Relay
Technical Reference Manual - ANSI Version
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 specified by the standard

a)
M
2
5
7
10
20
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.
b) b)
Normal Very
2.22E 2.34E
1.13E 1.26E
- -
1.01E 1.01E
1.00E 1.00E
1MRS755535
b) b)
Extremely Long time
2.44E 2.34E
1.48E 1.26E
- 1.00E
1.02E -
1.00E -