Melitta LOOK - Commissioning Tests: Initial Checks; Inspection, Wiring, and Earthing; Test Block Connection and Insulation Testing

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Section 4. COMMISSIONING TESTS
Note: Earlier relays were fitted with hand reset mechanical flag indicators, later
relays being fitted with a non-volatile hand reset LED trip indicator.
CAUTION:
If a flag indicator is fitted, damage is likely to be incurred if the flag indicator/
armature assembly of a miniature relay is actuated manually with a screwdriver/
probe. Flags should always be reset with the cover in position by the mechanism
provided.
4.1 Inspection and wiring check
Carefully examine the module and case to see that no damage has occurred during
transit. Check that the relay serial number on the module, case, cover and resistor
assembly (when an assembly is required) are identical and that the model number
and rating information are correct.
Check that the external wiring is correct to the relevant relay diagram or scheme
diagram. The relay diagram number appears inside the case. Particular attention
should be paid to the wiring of the external resistors Rext 1 and Rext 2 to the relay (if
required on scheme).
4.1.1 Electrostatic discharges (ESD)
The relay uses components which are sensitive to electrostatic discharges.When
handling the module, care should be taken to avoid contact with components and
electrical connections. When removed from the case for storage, the module should
be placed in an electrically conducting anti-static bag. See full recommendations
inside the front cover of this manual.
4.2 Connection of the MMLG test block
If a test block MMLG is provided, the connections should be checked to the scheme
diagram, particularly that the supply connections are to the live side of the test block
(coloured orange) – the odd numbered terminals. The auxiliary supply voltage to the
scheme should be routed via the test block terminals 13 and 15. To facilitate ease of
wiring the MMLG should be located at the right hand side of the assembly.
4.3 Earthing
Ensure that the case earthing connection above the rear terminal block is used to
connect the relay to the local earth bar.
4.4 Insulation check
The relay and its associated wiring, may be insulation tested between:
– all electrically isolated circuits.
– all circuits and earth.
An electronic or brushless insulation tester should be used, having a dc voltage not
exceeding 1kV. Accessible terminals of the same circuit should first be strapped
together. Deliberate circuit earthing links, removed for the tests must subsequently be
replaced.