In a Petersen coil compensated network is usually used directional sensitive earth fault protection
which characteristics is wanted to be controlled in between Varmetric and Wattmetric based on if the
Petersen coil is connected when the network is compensated or is it open when the network is
unearthed.
Figure. 5.5.2. - 120. Setting group control with 1 wire connection from Petersen coil status.
By monitoring the state of the Petersen coil connection the setting group control can be applied either
with 1 wire or 2 wire connection depending of the application requirements. In case of 1 wire
connection is allowed the setting group change logic can be applied as in the gure above. Petersen
coil status on controls SG1 to be active and if the coil is disconnected SG2 is active. With this practice
if the wire is broken for some reason the setting group would always be controlled to SG2.
With 2 wires connection when the Petersen coil state is monitored in both status more security can be
achieved. In addition to the direct connection below also additional logic can be added to the control
similarly to the 1 wire control. By that way single wire loss will not effect to the correct setting group
selection.
Figure. 5.5.2. - 121. Setting group control with 2 wire connection from Petersen coil status.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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