7SR18 Commissioning & Maintenance Guide
Unrestricted ©2018 Siemens Protection Devices Limited Page 11
Section 2: Protection Functions
This section details the procedures for testing each protection function of the relay. They 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.
The exact model type must be checked to confirm the functions available in each type.
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 matrix below indicates functions where function conflicts may occur during testing, consideration should be
given to disabling functions to avoid interference.
Any LED can be assigned to be a General Pickup LED in the Output Matrix menu and used to assess operation
of functions during testing if other functions are disabled or if the setting allocating General Pickup is temporarily
modified.
It should be considered that where several overlapping elements are used simultaneously, the overall protection
operate time may be dependent on the operation of different individual elements at the various levels of applied
current. The resulting composite characteristic may be tested by enabling all of the relevant applicable elements
or the element operations can be separated or disabled and tested individually.
All relay settings should be checked before testing begins. It is recommended that the relay settings are extracted
from the relay using Reydisp Evolution software and a copy of these settings is stored for reference during and
after testing. It may be necessary to disable some protection functions during the testing of other functions to
allow unambiguous results to be obtained.
Care must be taken to reset or re-enable any settings that have been temporarily altered during the testing before
the relay can be put into service. At the end of testing the relay settings should be compared to the file extracted
at the start to ensure that errors have not been introduced.
Function
Under Test
Phase Overcurrent
Cold Load
Derived E/F
Measured E/F
NPS Overcurrent
Undercurrent
Thermal
CB Fail
CT supervision
Broken Conductor
Trip cct
Supervision
Inrush Detector
Phase Overcurrent O O O O O O
Cold Load O O O O O O
Derived E/F O O O O O O O
Measured E/F O O O O
NPS Overcurrent O O O O O O
Undercurrent O O O
Thermal O O O
CB Fail O O O O O O
CT supervision O O
Broken Conductor O O O O
Inrush Detector
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