MCset 4 - 24 kV - engineering site - Schneider Electric

Voltage test on the main
circuits
How to prepare the units
Operations to be carried out on
units not directly connected to
the testing equipment
76 - 07897542EN indice: D0
Tests on site
After erection, the equipment shall be tested
in order to check the correct installation.
The power-frequency test voltage shall be
80% of the rated test value (40kV rms),
because the units have already been tested
in Schneider Electric factory at 00% of the
voltage rated value) and shall be applied
to each phase conductor of the main circuit
for minute earthing the other two phase
conductors.
The leads from the testing equipment shall
be connected to the MV cable lugs of a unit.
This requires the opening of a lower door
during the test for passing the
above-mentioned leads.
For a complete description of the following
operations, please consult the SF
circuit-breaker instruction for use handbook.
Warning
This preparation entails the bypass of some
interlock. Only appropriately trained staff
shall be allowed to operate.
The procedures described in the following
shall be strictly applied.
Voltage transformers and lightening
arresters, if any, shall be disconnected
during the voltage tests at power frequency
in order to avoid severe damages.
NB: In units equipped with VTs withdrawable
fuse version, disconnect the fuses. In units
equipped with fixed VTs, disconnect the VTs
power supply primary circuit.
CTs secondaries shall be short-circuited
at the LV terminal boards (if the auxiliary
circuits are open).
During the voltage tests, all the unit shall be
fitted with the relevant circuit-breakers.
The circuit-breakers shall be plugged in
service position and closed.
Since hand closing is not permitted with
closed doors, a special procedure is
required (see below) when auxiliary power
supply is not available.
Obviously, the MV cables shall be
disconnected and the earthing switch shall
be opened.
- Circuit-breaker in disconnected position
and the compartment door open.
- Lift the locking rod A located on the top of
the circuit-breaker mechanism.
- Insert spacer U to keep the rod in raised
position.
- Push the circuit-breaker to the service
position and remove spacer U.
- Charge the closing spring of the
circuit-breaker and close it by pressing
pushbutton “ I ”.
Schneider Electric