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7.2 Inspection
• Where necessary, the working area must be isolated and secured against reconnection in
accordance with the Safety Regulations specified by IEC and appropriate national standards before
inspection;
• Correct condition of the switchgear should be monitored by regular inspections;
• Under normal operating conditions, inspection should be carried out once every four years by
specially trained professional electricians;
• Under abnormal operating conditions (including adverse climatic conditions) and/or special
environmental stresses (heavy pollution and aggressive atmosphere, among others), inspection
may be necessary at shorter intervals.
• Inspection is primarily to carry out a visual check for grime, corrosion and moisture:
- Effects of high temperature on the main circuits;
- Traces of partial discharge on the insulating material parts;
- Traces of leakage current on the insulating material parts;
- Surfaces of the contact systems;
• However, inspection must also include correct mechanical/electrical operation of the following parts:
switching devices, actuating, interlocking, protection and signalling devices.
Special conditions
• On panels with additional ventilation devices due to increased ambient temperature (also see section
1.3):
1. Check flap 20.3 for correct operation. (Also see section 6.1.1 and figures 109, 110);
2. The centrifugal fan (if fitted) does not require any special maintenance. Its working life –
depending on the service conditions, and one significant parameter being the room temperature
- is approx. between 20,000 and 30,000 operating hours.
Checking readiness for operation can be carried out as follows:
a)Load-dependent functional test with controllable primary current supply of the relative instrument
transformer. on current rise:
1. to approx. 70% of the rated instrument transformer current, the fan must start;
2. to 80 % of the rated instrument transformer current, the fan must have reached the required
minimum air flow. Corresponding monitoring/signalling by the wind vane with microswitch.
b) Basic checking with temporary operation of the centrifugal fan with an external power supply of
220 V AC;
c) In both cases, check for unimpeded normal running of the fan and listen for any unusual bearing
noise. Remove any dirt on the fan rotor.
d) Check unimpeded operation of the wind vane and microswitch by starting the fan several times.
e) The wiring to removable horizontal partition 20 can be disconnected behind the right-hand side
duct cover. Follow the circuit diagram and carefully reconnect the wiring again on completion.
Caution: instrument transformer circuit
• With regard to the switching devices, their separate Instruction manual should be followed;
• Check all switchgear accessories and auxiliary devices (e.g. storage batteries);
• No partial discharge must occur on the surfaces of equipment at operating voltage. This can, for
example, be detected by characteristic noises, a clearly perceptible smell of ozone, or visible glowing
in the dark;
• Visually checking the contact system. We recommend turning the contact system alternately in order
to clean the inner contact points of the contact system.
The contact points should be cleaned if signs of overheating (discoloured surface) are visible (see
section 7.4);
• If any irregular conditions are detected, then relative repair measures must be taken.
7.3 Servicing
When, during an inspection as per paragraph 7.2, the need to carry out cleaning operations is noted,
proceed as follows:
• Where necessary, the work area must be disconnected and locked against reconnection in
conformity with the safety standards specified in the IEC directive and in the relative national
regulations;
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