Generator Inverse Time-Overcurrent Ansi# Iec 255 - Woodward easYgen-2000 Series User Manual

4.4.1.14

Generator Inverse Time-Overcurrent ANSI# IEC 255

General notes
37535B
Configure Monitoring > Generator > Generator Inverse Time-Ove...
The current produced by the generator is monitored depending on
how parameter "Generator current measuring" (param‐
eter 1850 Ä p. 97) is configured. If an overcurrent condition is
detected, the fault recognition time is determined by the configured
tripping characteristic curve and the measured current.
The tripping time is faster as the measured current increases in
magnitude according to a defined curve. According to IEC 255
three different characteristics are available.
If this protective function is triggered, the display indicates "Inv.
time overcurr." and the logical command variable "06.22" will be
enabled.
"Normal inverse" characteristic:
n
t = 0.14 / (I/I ) 0.02
P
"Highly inverse" characteristic:
n
t = 13.5 / (I/I ) - 1) * t
P
"Extremely inverse" characteristic:
n
t = 80 / (I/I ) 2 - 1) * t
P
Variables:
t =tripping time
n
t = setting value time
n
P
I = measured fault current
n
I = setting value current
n
P
Please take into account during configuration:
for I :
n
start
I > I and I
start n start
for I the smaller I
n
P
curve
The maximum tripping time is 327 s. If a tripping time
greater than 327 s is configured, an overcurrent fault
condition will not be recognized.
easYgen-2200/2500 | Genset Control
- 1) * t [s]
P
[s]
P
[s]
P
> I
P
is, the steeper is the slope of the tripping
P
Configuration
129