ABB RELION REX640 Technical Manual page 666

Protection functions
The circuit diagrams of the application are recommended to be available. These are
required for checking the terminal block numbers of the current, trip, alarm and
possibly other auxiliary circuits.
The technical and application manuals contain application and functionality
summaries, function blocks, logic diagrams, input and output signals, setting
parameters and technical data sorted per function.
The minimum requirement for a secondary current injection test device is the ability
to work as a one phase current source.
The protection relay should be prepared for the test before testing a particular
function. The logic diagram of the tested protection function must be considered
while performing the test. All included functions in the protection relay are tested
according to the corresponding test instructions in this chapter. The functions
can be tested in any order according to user preferences. Therefore, the test
instructions are presented in alphabetical order. Only the functions that are in use
Operation is set to "On") should be tested.
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The response from the test can be viewed in different ways.
• Binary output signals
• Monitored data values in the LHMI (logical signals)
• A PC with a Web browser for WHMI use (logical signals and phasors)
All used setting groups should be tested.
Checking the external optical and electrical connections
The user must check the installation to verify that the protection relay is connected
to the other required parts of the protection system. The protection relay and all the
connected circuits are to be de-energized during the check-up.
Checking of CT circuits
The CTs must be connected in accordance with the terminal diagram provided with
the protection relay, both with regards to phases and polarity. The following tests
are recommended for every primary CT or CT core connected to the protection relay.
• Primary injection test to verify the current ratio of the CT, the correct wiring up
to the protection relay and correct phase sequence connection (that is L1, L2, L3.)
• Polarity check to prove that the predicted direction of the secondary current
flow is correct for a given direction of the primary current flow. This is an
essential test for the proper operation of the directional function, protection
or measurement in the protection relay.
• CT secondary loop resistance measurement to confirm that the current
transformer secondary loop DC resistance is within specification and that there
are no high resistance joints in the CT winding or wiring.
• CT excitation test to ensure that the correct core in the CT is connected to
the protection relay. Normally only a few points along the excitation curve are
checked to ensure that there are no wiring errors in the system, for example, due
to a mistake in connecting the CT's measurement core to the protection relay.
• CT excitation test to ensure that the CT is of the correct accuracy rating and
that there are no short circuited turns in the CT windings. Manufacturer's design
curves should be available for the CT to compare the actual results.
666
Check that the wiring is in strict accordance with the supplied
connection diagram.
1MRS759142 F
REX640
Technical Manual