Maintenance: here are all the activities that must be performed, required by law, to decrease the risk of injury and avoid criminal liability
The maintenance of low-voltage electrical panels is not only a legal requirement, but it is also a good practice that is important to pursue in order to avert the risk of injury and thus for the safety of people.
Keeping track of the activities that need to be carried out for maintenance can be complex in light of their numerousness. This month we try to understand what the essential tricks are with the help of guidelines from the National Federation of Electrical and Electronics Enterprises (ANIE).
INSTALLATION AND COMMISSIONING
The location of the switchboard is the first aspect to consider. In fact, the cabinet should be located in a place that is adequately accessible to the operating parts and other parts that can be serviced. Size and positioning should be well considered when designing cabinets and technical rooms. In addition, spaces between paintings and between walls should allow easy access to exits.
When it is necessary to design electrical switchboards of considerable size, it is necessary to define mechanical subdivision points to construct multiple transport sections. These sections must be joined before the entire structure is attached to the floor, which must be level and free of unevenness.
Then some checks should be carried out to minimize possible hazards during transport.
According to the ANIE Federation, these are the operations to be carried out:
- General visual inspection (cleanliness and transport damage);
- verification tightening connections;
- Protective circuit tightening check;
- Checking the insulation resistance value between the phases and between them and the ground;
- Verification of correct opening/closing operation on each switch;
- Verification of mechanical and electrical interlocks;
- Verification of pull-out and insertion maneuver functionality on pull-out/removable switches;
- Checking the connection of auxiliary and measuring circuits;
- Checking that any electronic measuring instruments are turned on correctly;
- Checking that relays equipped with a test button (switch in closed position) are properly tripped;
- verification auxiliary signaling;
- Verification of the opening and emergency release coils;
- Verification of duty cycles for motorized switches;
- Checking auxiliary circuits of the withdrawable switches in the sectioned position;
- Checking the setting of the switches;
- Checking indications of voltmeters, lamps, analyzers;
- Differential trip verification by test button;
- Checking correct relay switching of electronic switches.
After these activities, it is necessary to proceed with commissioning, which involves:
- The closing of the line arrival switches;
- The verification of the proper operation of measuring instruments, lamps and network analyzers;
- The individual closing of output switches;
- The verification of the operation of utilities (if possible).
It is the IEC standards that provide for specific maintenance activities. Routine maintenance is referred to when the goal is to prevent failure and limit degradation of the electrical panel.
A maintenance program should include these activities:
- Framework integrity check;
- Checking mechanical connections framework structure;
- Visual check for mechanical, thermal and electrical damage including any oxidation;
- Temperature verification through thermography;
- verification of presence of nameplate and availability of wiring diagram;
- Equipment and wiring diagram correspondence check;
- Verify calibration of protective devices based on the detected loads;
- Checking the efficiency of measuring instruments;
- Check integrity of fuses and signal lamps (auxiliary circuits in general);
- Verification of mechanical operation of equipment;
- Functional verification of differential protection devices;
- MV/LV functional drag test (if any);
- Functional test safety circuits;
- Verification of connection to the grounding system and protective conductors;
- Checking tightening torques of bolted elements;
- Terminal block check, tightening and connections;
- General cleaning of the switchboard and related equipment.
Finally, extraordinary maintenance is carried out as a result of an unplanned failure or for an operation not included in routine maintenance.
In this case, the steps to be taken are as follows:
- Securing the switchboard by opening the main disconnecting device and then verifying the circuit opening by instrumentation;
- Identification of the cause of the failure and removal;
- Cleaning of blackened parts (if necessary);
- Visual inspection of busbars, appliances, insulation parts, etc;
- Verification of equipment efficiency;
- Replacement of damaged appliances, bars, cables or other parts (if necessary);
- Checking the tightening torques of the connections;
- Detachment of the affected utility for verification of insulation resistance and dielectric strength;
- Restoring utility connection, powering circuits, and verifying proper operation.