Application Notes P54x/EN AP/La4
MiCOM P543, P544, P545 & P546
(AP) 6-57
AP
3.2.6 Zone 1 phase and ground reach settings
Required Zone 1 reach is to be 80% of the line impedance between Green Valley and Blue
River substations.
Setting the Relay in the SIMPLE setting mode (recommended):
Set Zone 1 Ph and Zone 1 Gnd reach = 80%
From this the relay will automatically calculate the required ohmic reaches, or they can be
entered manually in the ADVANCED mode, as follows:
Required Zone 1 reach = 0.8 x 100 x 0.484 79.4 x 0.12
Z1 = 4.64 79.4 secondary
The Line Angle = 80
Therefore actual Zone 1 reach, Z1 = 4.64 80 secondary.
3.2.7 Zone 2 phase and ground reach settings
Req
uired Zone 2 impedance = (Green Valley-Blue River) line impedance + 50%
(Blue River-Rocky Bay) line impedance
Z2 = (100+30) x 0.484 79.4 x 0.12 = 7.56 79.4
secondary.
The Line Angle = 80
Actual Zone 2 reach setting = 7.56 80 secondary
Alternatively, in SIMPLE setting mode, this reach can be set as a percentage of the
protected line. Typically a figure of at least 120% is used.
3.2.8 Zone 3 phase and ground reach settings
Req
uired Zone 3 forward reach = (Green Valley-Blue River + Blue River-Rocky Bay) x
1.2
= (100+60) x 1.2 x 0.484 79.4 x 0.12
Z3 = 11.15 79.4 ohms secondary
Actual Zone 3 forward reach setting = 11.16 80 ohms secondary
Alternatively, in SIMPLE setting mode, this reach can be set as a percentage of the
protected line.
3.2.9 Zone 3 reverse reach
In
the absence of other special requirements, Zone 3 can be given a small reverse reach
setting, of Z3’ = 10%. This is acceptable because the protected line length is > 30km.
Zone 4 Reverse Settings with POR and BLOCKING schemes
Where zone 4 is used to provide reverse directional decisions for Blocking or Permissive
Overreach schemes, zone 4 must reach further behind the relay than zone 2 for the remote
relay. This can be achieved by setting: Z4 ((Remote zone 2 reach) x 120%), where mho
characteristics are used.
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