When protection IEDs are combined with built-in control, the test interval can be
increased drastically, up to for instance 15 years, because the IED continuously reads
service values, operates the breakers, and so on.
14.2.1 Visual inspection
SEMOD56525-5 v3
Prior to testing, the protection IEDs should be inspected to detect any visible damage that may have
occurred (for example, dirt or moisture deposits, overheating).
Make sure that all IEDs are equipped with covers.
14.2.2 Maintenance tests
SEMOD56534-1 v1
SEMOD56528-5 v6
To be made after the first half year of service, then with the cycle as proposed above and after any
suspected maloperation or change of the IED setting.
Testing of protection IEDs shall preferably be made with the primary circuit de-energized. The IED cannot
protect the circuit during testing. Trained personnel may test one IED at a time on live circuits where
redundant protection is installed and de-energization of the primary circuit is not allowed.
Hitachi Power grids protection IEDs are preferably tested by aid of components from the COMBITEST
testing system or FT test systems described in information B03-9510 E. Main components are RTXP
8/18/24 test switch usually located to the left in each protection IED and RTXH 8/18/24 test handle, which
is inserted in test switch at secondary testing. All necessary operations such as opening of trip circuits,
short-circuiting of current circuits and opening of voltage circuits are automatically performed in the right
order to allow for simple and safe secondary testing even with the object in service.
Important components of FT test system are FT1, FTx, FT19, FT19RS, FR19RX switches and
assemblies as well as FT-1 test plug.
14.2.2.1 Preparation
SEMOD56528-10 v2
Before starting maintenance testing, the test engineers should scrutinize applicable circuit diagrams and
have the following documentation available:
• Test instructions for protection IEDs to be tested
• Test records from previous commissioning and maintenance tests
• List of valid settings
• Blank test records to fill in measured values
14.2.2.2 Recording
SEMOD56528-14 v2
It is of utmost importance to carefully record the test results. Special test sheets covering the frequency
of test, date of test and achieved test values should be used. IED setting list and protocols from previous
tests should be available and all results should be compared for differences. At component failures,
spare equipment is used and set to the requested value. A note of the exchange is made and the new
measured values are recorded. Test records for several years of testing should be stored in a common
file for a station, or a part of a station, to give a simple overview of the period of testing and achieved test
values. These test records are valuable when analysis of service disturbances shall be done.
Section 14 1MRK 504 165-UUS Rev. J
Commissioning and maintenance of the fault clearing system
302 Transformer protection RET670
Commissioning manual
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