Areva MiCOM P921 - Page 58

P92x/EN TD/E11 Technical Guide
Technical Data
Page 12/30 MiCOM P921-P922-P923
3.2.3 Inverse Time Delay Characteristic
The inverse characteristic is defined by the following formula :
÷
÷
÷
÷
ø
ö
ç
ç
ç
ç
è
æ
-
=
1
Vs
V
TMS
t
where :
t = operating time in seconds
TMS = time Multiplier Setting
V = applied input voltage
Vs = relay setting voltage
NOTE : this equation is only valid for
V
s
V
ratio > than 1.1
Setting Range Step Size
TMS 0.5 – 100 0.5
Setting Range Step Size
TRESET (only DT) 0 – 100s 0,01s
When the V> is associated with IDMT curve, the recommended maximum setting
value should be less or equal to max. setting range divided by 20.