Pxxxx/EN SS/C11
Safety Section Page 7/10
External test blocks and test plugs
Great care should be taken when using external test blocks and test plugs such as
the MMLG, MMLB and MiCOM P990 types, hazardous voltages may be
accessible when using these. *CT shorting links must be in place before the
insertion or removal of MMLB test plugs, to avoid potentially lethal voltages.
*Note – when a MiCOM P992 Test Plug is inserted into the MiCOM P991 Test
Block, the secondaries of the line CTs are automatically shorted, making them
safe.
Fibre optic communication
Where fibre optic communication devices are fitted, these should not be viewed
directly. Optical power meters should be used to determine the operation or signal
level of the device.
Cleaning
The equipment may be cleaned using a lint free cloth dampened with clean water,
when no connections are energised. Contact fingers of test plugs are normally
protected by petroleum jelly which should not be removed.
5. DECOMMISSIONING AND DISPOSAL
Decommissioning:
The supply input (auxiliary) for the equipment may include capacitors across the
supply or to earth. To avoid electric shock or energy hazards, after completely
isolating the supplies to the equipment (both poles of any dc supply), the
capacitors should be safely discharged via the external terminals prior to
decommissioning.
Disposal:
It is recommended that incineration and disposal to water courses is avoided.
The equipment should be disposed of in a safe manner. Any equipment
containing batteries should have them removed before disposal, taking
precautions to avoid short circuits. Particular regulations within the country of
operation, may apply to the disposal of batteries.
6. EQUIPMENT WHICH INCLUDES ELECTROMECHANICAL ELEMENTS
Electrical adjustments
It is possible to change current or voltage settings on some equipment by direct
physical adjustment e.g. adjustment of a plug-bridge setting. The electrical power
should be removed before making any change, to avoid the risk of electric shock.
Exposure of live parts
Removal of the cover may expose hazardous live parts such as relay contacts,
these should not be touched before removing the electrical power.
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