Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-77
OP
Z1
Z1
Z2
Z1
Z2
Z1
40ms
0
&
&
0
18ms
&
Trip
Z2
1
LOL-A
LOL-B
LOL-C
P1146ENa
Figure 52 Loss of load accelerated trip scheme (Distance option only)
For circuits with load tapped off the protected line, care must be taken in setting the loss of
load feature to ensure that the I< level detector setting is above the tapped load current.
When selected, the loss of load feature operates in conjunction with the main distance
scheme that is selected. In this way it provides high speed clearance for end zone faults
when the Basic scheme is selected or, with permissive signal aided tripping schemes, it
provides high speed back-up clearance for end zone faults if the channel fails.
Note: Loss of load tripping is only available where 3 pole tripping is used.
The detailed Logic Diagram is shown in Figure 53.
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