ABB Relion 670 series - Page 649

Inverse delays as per figure 348, can be modified (limited) by two special definite delay settings,
namely t_MaxTripDelay and t_MinTripDelay , see figure 347.
0 M
max
– Pickup1
M
max
t_MinTripDelay
Pickup1
E
max
E (only if f = fn = const)
t_MaxTrip
Delay
inverse delay law
overexcitation
under -
excitation
delay in s
ANSI99001067-2-
en.vsd
Overexcitation M-Pickup1
Excitation M
M=Pickup1
ANSI99001067 V2 EN-US
Figure 347: 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 ).
1MRK 502 066-UUS B Section 9
Voltage protection
643
Technical manual