109
Current protection Chapter 11
Verifying settings by secondary
injection
6.7.1 Checking the phase current operate value, IP>
The check of the IP> current level is best made in FunctionMode=Current and BuTripMode=
“1 out of 3” or “2 out of 4”.
Procedure
1. Apply the fault condition, including start of BFP, with a current below
set
IP>.
2. Repeat the fault condition and increase the current in steps until a
trip occurs.
3. Compare the result with the set IP>.
4. Disconnect AC and start input signals.
Note: If “No I> check” or “Retrip off” is set, only back-up trip can be
used to check set IP>.
6.7.2 Checking the residual (EF) current operate value “IN>” set below “IP>”
The check of low set IN> current level is best made in FunciontMode= Current and BuTrip-
Mode= “1 out of 4”.
Procedure
1. Apply the fault condition, including start of BFP, with a current just
below set
IN>.
2. Repeat the fault condition and increase the current in steps until trip
appears.
3. Compare the result with the set IN>.
4. Disconnect AC and start input signals.
6.7.3 Checking the re-trip and back-up times
The check of the set times can be made in connection with the check of operate values above.
Choose the applicable function and trip mode, such as FunctMode= Current and RetripMode =
I> check.
Procedure
1. Apply the fault condition, including start of BFP, well above the set
current value. Measure time from “Start of BFP”.
2. Check the re-trip t1 and back-up trip times t2 and t3
In applicable cases the back-up trip for multi-phase start “t2MPh” and
back-up trip 2, “t2 + t3” can also be checked. For check of “t2MPh” a
two-phase or three-phase start shall be applied.
3. Disconnect AC and start input signals.
6.7.4 Verifying the re-trip mode
Choose the mode below, which corresponds to the actual case. In the cases below it is assumed
that FunctionMode = Current is selected.
To Next Page
Loading...
