Preliminary Work
745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–4
GE Multilin
Preliminary Work
Description
1. Review appropriate sections of this manual to familiarize yourself with the relay.
Confidence in the commissioning process comes with knowledge of the relay
features and methods of applying settings.
2. Verify the installation to ensure correct connections of all inputs and outputs.
3. Review the relay settings and/or determine features and settings required for
your installation. In large utilities a central group is often responsible for
determining which relay features will be enabled and which settings are
appropriate. In a small utility or industrial user, the on-site technical person is
responsible both for the settings and also for the complete testing of the relay.
4. Set the relay according to requirements. Ensure that the correct relay model
has been installed. A summary table is available in this manual for users to
record all the relay settings. When the testing is completed, users should verify
the applied relay settings, and verify that all desired elements have been
enabled, using the enerVista 745 Setup software or the relay front panel.
5. Verify that the relay rated AC current matches the CT secondary value.
6. Verify that the relay rated AC voltage matches the VT secondary value.
7. Verify that the relay rated frequency setting matches the power system
frequency.
8. Open all blocking switches so as not to issue an inadvertent trip signal to line
breakers.
9. Verify that the auxiliary supply matches relay nameplate. Turn the auxiliary
supply ON.
10. Verify that all grounding connections are correctly made.
To facilitate testing it is recommended that all functions be initially set to Disabled.
Every feature which will be used in the application should be set per desired
settings, enabled for the specific commissioning test for the feature, then returned
to Disabled at completion of its test. Each feature can then be tested without
complications caused by operations of other features. At the completion of all
commissioning tests all required features are then Enabled.
It is necessary to keep track of modifications/changes made to settings
during the course of these commissioning steps and ensure that all settings
are returned to the ‘in-service’ values at the end of the tests, prior to
placing the relay into service.
Dielectric Strength
Testing
The 745 is rated for 2000 V DC isolation between relay contacts, CT inputs, VT
inputs and the safety ground terminal G12. Some precautions are required to
prevent 745 damage during these tests.
Filter networks and transient protection clamps are used between control power and
the filter ground terminal G11. This filtering is intended to filter out high voltage
transients, radio frequency interference (RFI), and electromagnetic interference
(EMI). The filter capacitors and transient suppressors could be damaged by
application continuous high voltage. Disconnect filter ground terminal G11 during
testing of control power and trip coil supervision. CT inputs, VT inputs, and output
relays do not require any special precautions. Low voltage inputs (< 30 V) such as
RTDs, analog inputs, analog outputs, digital inputs, and RS485 communication ports
are not to be tested for dielectric strength under any circumstance.
CAUTION
Summary of Contents for Multilin 745
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