Section 4: Control & Logic Functions; Zone Switching; Figure 4-1 Logic Diagram: Protection In/Out Switching - Siemens 7SR23 DAD Manual

Section 4: Control & Logic Functions
4.1

Zone Switching

In/Out switching of the high impedance protections is provided to aid commissioning and testing.
When the 'Zone Switch Out' feature is initiated the operation of the differential protection and CT supervision
monitoring is inhibited. User selected output contacts assigned to 'CT50' are operated when 'Zone Switchout CT
Shorting' is selected to Enabled. The connection of these contacts in the protection scheme ensures that any
unbalance current in the differential circuit does not flow through the relay/stabilising resistor.
Operation of the Zone Switch Out feature can be initiated from:
A binary or virtual input.
Data comms
Control menu
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Figure 4-1 Logic Diagram: Protection In/Out Switching
Chapter 1) 7SR23 DAD Description Of Operation
Chapter 1 Page 23 of 36