Section 2: Protection Functions - Siemens 7SR242 Duobias Technical Manual

Section 2: Protection Functions

This section details the procedures for testing each protection function of the 7SR24 relay. These tests are carried
out to verify the accuracy of the protection pick-ups and time delays at setting and to confirm correct operation of
any associated input and output functionality.
Guidance for calculating test input quantities is given in the relevant test description where required. In many
cases it may be necessary to disable some functions during the testing of other functions, this prevents any
ambiguity caused by the operation of multiple functions from one set of input quantities. The 'Function Config'
Menu provides a convenient high level point at which all elements of a particular function can be
Enabled/Disabled to suit testing. The 'Config' tab in 'ReyDisp Evolution' can be used to 'Enable/Disable' individual
elements. Note that this screen disables functions by applying setting changes to the relay and that any changes
must be sent to the relay to take effect and settings must be returned to their correct value after testing.
The table below indicates functions where function conflicts may occur during testing, consideration should be
given to disabling functions to avoid interference.
Function
Under
Test
Biased Diff.
Diff. Highset O
Phase OC O
Derived E/F O
Measured E/F O
Restricted E/F O
Open Circuit O
NPS OC O
Undercurrent O
Thermal O
U/O voltage
Neutral OV
U/O Frequency
Overfluxing
CB Fail O
74TCS/74CCS
Inrush Detector
O/fluxing Detector
The General Pickup LED can be used to assess operation of functions during testing if other functions are
disabled or if the setting allocating General Pickup is temporarily modified.
©2015 Siemens Protection Devices Limited
Chapter 6) 7SR242 Duobias Commissioning & Maintenance Guide
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