Areva MiCOM P921 - Page 63

Technical Guide P92x/EN TD/E11
Technical Data
MiCOM P921-P922-P923 Page 17/30
3.4.3 Inverse Time Delay Characteristic
The inverse characteristic is defined by the following formula :
÷
÷
÷
÷
÷
ø
ö
ç
ç
ç
ç
ç
è
æ
-
=
1
V
V
TMS
t
S
2
where :
t = operating time in seconds
TMS = time Multiplier Setting
V
2
= applied input voltage
Vs = relay setting voltage
Setting Range Step Size
TMS 0,5 - 100 0.5
Setting Range Step Size
tRESET (only DT) 0 – 100s 0.01s
3.4.4 Definite time delay characteristics
Setting Range Step Size
tV
2
> 0 – 599s 0.01s
tV
2
>> 0 – 599s 0.01s
3.4.5 Hysteresis
Hysteresis fixed 95%
When the V
2
> is associated with IDMT curve, the recommended maximum setting
value should be less or equal to max. withstand voltage of the VT inputs divided by
20.
3.5 Positive sequence undervoltage (ANSI code 27D) only P922 & P923
3.5.1 Threshold settings (secondary values)
- Nominal voltage range : 57 – 130V
Setting Range Step Size
V
1
< Voltage set 5 – 130V 0.1V
V
1
<< Voltage set 5 – 130V 0.1V
- Nominal voltage range : 220 – 480V
Setting Range Step Size
V
1
< Voltage set 20 – 480V 0.5V
V
1
<< Voltage set 20 – 480V 0.5V