Alstom MiCOM P546 - 1.25 Phase fault overcurrent protection

P54x/EN OP/La4 Operation
(OP) 5-78 MiCOM P543, P544, P545 & P546
OP
DDB Loss of Load Trip (654)
&
&
&
&
&
&
1
&
P1547ENb
&
DDB Any Trip (522)
SET Trip 3 Ph En
DDB I>LoL A (1365)
DDB I>LoL B (1366)
DDB I>LoL C (1367)
tLoL
DDB Zone 2 AN (966)
DDB Zone 2 BN (967)
DDB Zone 2 CN (968)
DDB Zone 2 AB (969)
DDB Zone 2 BC (970)
DDB Zone 2 CA (971)
1
18ms
S
R
Q
DDB LoL Inhibit (491)
Set Dominant
Latch
SET LoL Enabled
SET LoL on Ch 1 Fail
DDB Channel 1 Fail (317)
DDB Channel 2 Fail (318)
SET LoL on Ch 2 Fail
SET LoL on Ch 1 AND 2 Fail
SET LoL on Ch 1 OR 2 Fail
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&
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1
1
&
1
1
Figure 53 Loss of load (Distance option only)
1.25 Phase fault overcurrent protection
Phase fault o
vercurrent protection is provided as a form of back-up protection that could be:
 Permanently disabled
 Permanently enabled
 Enabled only in case of VT fuse/MCB failure
 Enabled only in case of protection communication channel failure
 Enabled if VT fuse/MCB or protection communication channel fail
 Enabled if VT fuse/MCB and protection communication channel fail
In addition, each stage may be disabled by a DDB (463,464,465 or 466) Inhibit I > x (x = 1,
2, 3 or 4)
It should be noted that phase overcurrent protection is phase segregated, but the operation
of any phase is mapped to 3 phase tripping in the default PSL.
The VTS element of the relay can be selected to either block the directional element or
simply remove the directional control.
The first two stages can be set either inverse time or definite time only. The third and fourth
stages have a DT characteristic only. Each stage can be configured to be directional
forward, directional reverse or non-directional.
For the IDMT characteristics the following options are available.
The IEC/UK IDMT curves conform to the following formula:
t = T x







(
/s)

–1
+ L