ABB SPAJ 160 C User Manual And Technical Description page 54

Time/current
characteristics
ANSI-type
characteristic
Phase unbalance-
type characteristic
(modified 99-10)
18
The operation of the overload stage I
on ANSI and IEC inverse time characteristic.
I/Ib> t [s]
1.15 1620
1.20 270
1.30 54
1.40 13.5
1.70 0.9
2.00 0.27
2.20 0.10
Minimum operating time is 100 ms.
The graph of the characteristic is shown in Fig.5.
The operation of the phase unbalance stage ∆I
is based on inverse time characteristic near to
normal inverse. The characteristic is based on
the following mathematical expression:
t[s] = k x 101.2/[(100 x ∆I/∆I
where
t = operating time in seconds
k = time multiplier
∆I
= current value
∆I
> = set current value
2
> is based
b
standard durations [s]
1800 IEC 871-1
300 IEC 871-1
60 ANSI 18-1980, IEC 871-1
15 ANSI 18-1980
1 ANSI 18-1980
0.3 ANSI 18-1980
0.12 ANSI 18-1980
> Note!
2
It is possible to increase the inverse time char-
acteristic by a factor 10 by setting switch SGF/6
to position 1.
>)-97]+0.02 The normal current range is defined as 1...2
2
times the setting current. Additionally the relay
must start at the latest when the current exceeds
a value of 1.05 times the setting current.
Minimum operating time is 100 ms. For cur-
rents above two times the rated current ∆I the
relay levels out to definite time operation.
The graph of the characteristic is shown in Fig.6.