ABB Relion 670 Series Technical Reference Manual page 541

1MRK505222-UUS C
Technical reference manual
delay in s
t_MaxTrip
Delay
under -
inverse delay law
excitation
overexcitation
0
M=Pickup1
Pickup1
ANSI99001067 V2 EN
Figure 272: Restrictions imposed on inverse delays by t_MaxTripDelay and
t_MinTripDelay
A definite maximum time, t_MaxTripDelay, can be used to limit the operate time at
low degrees of overexcitation. Inverse delays longer than t_MaxTripDelay will not be
allowed. In case the inverse delay is longer than t_MaxTripDelay, OEXPVPH (24)
trips after t_MaxTripDelay seconds.
A definite minimum time, t_MinTripDelay, can be used to limit the operate time at
high degrees of overexcitation. In case the inverse delay is shorter than
t_MinTripDelay, OEXPVPH (24) function trips after t_MinTripDelay seconds. The
inverse delay law is not valid for values exceeding Mmax. The delay will be tMin,
irrespective of the overexcitation level, when values exceed Mmax (that is, M>Pickup1).
t_MinTripDelay
M – Pickup1
Overexcitation M-Pickup1
max
M
Excitation M
max
E (only if f = fn = const)
E
max
ANSI99001067-2-
en.vsd
Section 8
Voltage protection
535