Field Testing And Commissioning; Preparation; Physical Inspection - Siemens 7UT51 Instruction Manual

7UT51 v3
18

Field Testing and Commissioning

Hazardous voltage or current.
Can cause death, serious personal
injury, or property damage.
Only qualified personnel should test or
commission a relay. Read and understand
this manual and the manuals for any test
equipment before proceeding.
Before performing work on CT wiring,
always short circuit the secondary of all
the CTs.
To avoid damage to the relay, ensure that
output contacts do not break currents
greater than their rating.
To avoid damage to the relay, ensure that
any control power or test value applied to
the relay does not exceed the
corresponding input's limit.
This chapter describes commissioning a 7UT51 relay,
including procedures to verify correct operation and
configuration.
The procedures in this chapter test functions of both
the 7UT512 and 7UT513 models. When testing a
7UT512, simply skip sections that apply only to a
7UT513. Likewise, any functions not used in a
particular application need not be tested.
Complete testing of all required protective functions,
discrete inputs, signal contacts, and trip contacts is
recommended prior to installation.
The procedures take into account that the protection
settings may vary, but they assume that the relay's
contact inputs, contact outputs, and LEDs are
configured with their default values (unless otherwise
noted). If they have been configured differently, the
user must determine the expected behavior of the
relay and compare it to the observed results of the
procedure.
Note: All secondary testing sets and equipment must
be removed. All current circuits should be
connected to the relay.
PRIM-2330C
Field Testing and Commissioning
18.1

Preparation

18.1.1

Physical Inspection

Check all wiring from the relay to all substation
components such as CTs, breaker trip coils, status
contacts, etc. Inspect all cables, junction boxes, circuit
breakers, etc., for proper wiring, shorting type terminal
blocks at proper locations, tight connections (screw
heads must be tight against wire). Check that shorting
screws are removed from CT blocks that will be in
service. Inspect boxes, switches, relays, etc., for any
material such as wires, screws, lugs, tags, etc., that
could short or ground the circuit. Visually wire check
all current circuits.
Check auxiliary switches for connections, wipe, and
adjustment per manufacturer's instructions,
particularly the operating relation with respect to main
blade make and break.
Ensure that current inputs are wired with an A-B-C
phase rotation. Ensure that settings match those
prepared by a qualified protective relaying engineer.
Check the connections to the relay:
• Ensure that inputs to the relay are connected with
the correct polarity.
• Ensure that trip circuits are disconnected from the
relay trip contacts and are left open-circuited.
Also, disconnect from external breaker failure
devices any of the relay outputs that are being
tested.
Once acceptance tests have been completed
(see Chapter 16) and the relay is installed with the
in-service settings applied and tested, and the above
physical inspections made, the commissioning tests
and checks can be performed.
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