ABB OVB-SDB, Instructions Manual, Page: 9 / 64

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3.3 Safety Precaution
When working on high-voltage circuit breaker the below-mentioned risk must be taken into
consideration and corresponding safety measures taken.
RISK SAFETY MESAURES
1) Work next to high voltage Warning plate is placed inside the
door of the operating device.
Disconnect the supply and earth near
the workplace. If work must be
carried out near energized parts of
the plant, it has to follow local safety
regulation of the organization
responsible for the circuit breaker.
2) Work on ladders and platforms The work shall follow the directions
of the authority for occupational
safety and health. Avoid work in
severe weather conditions, which
entails a great deal of climbing for
short periods.
3) Work with low- voltag e.
Both D.C. and A.C. voltage
may be drawn to the operating
device.
4) Risk in operating mechanism
and link system
The spring operated device has
energy stored in the opening
spring, when it is in charged
condition. The device can be
activated by heavy vibrations or
unintentional, slight touch on
mechanical latch parts.
5) Work on pressurized porcelain
Insulator
s.
Normally, the work pressure is
up to 1.2 bar absolute. Damages
in the porcelain can cause risk of
the porcelain breaking.
Do not connect control or heating
voltage until all connection work is
completed.
Warning plate is placed on the
supporting frame.
No work must be carried out unless
the closing and opening springs are
discharged, the circuit-breaker is in
position OFF “0” and the supply to
the motor is disconnected.
The operating mechanism must not
be operated unless it is connected to
the circuit
Work close to the insulators of the
circuit breaker that entails risk of
porcelain damage must not be
carried out until the gas pressure has
been lowered to 1.0 bar absolute
pressur
e.