WHAT IS IT?
Testing and maintenance of withdrawable air circuit breakers (ACBs) and/or medium/high voltage switchgear and transformers. Regular service of this equipment greatly extends its useful life and testing ensures that the equipment responds correctly under fault conditions, protecting the integrity of the electrical installation and the network supply.
These services are not a legal requirement but part of a best-practice approach to risk minimisation and ensure the long-term health of the electrical installation.
In addition EnergySafety – Guidelines for the safe management of high voltage (HV) installations require that:
Responsible persons for premises with an electricity supply at high voltage shall ensure that their installation; safely performs the function for which it is designed and intended; operates in accordance with the manufacturer’s requirements; is maintained in good order; and in the event of a fault or malfunction shall not create a hazard or cause interference to the network operator’s distribution network
This means that failure to properly maintain your private electrical infrastructure which results in interference with the operation of the municipal supply network may result in punitive action by the appropriate regulatory authority.
InfraRed Services has extensive expertise in installing, maintaining and servicing switchgear from all manufacturers, including (but not limited to):
- Schneider (Masterpact, RM6 etc.)
- Terasaki Tembreak/Tembreak2
- General Electric (GE)
- NHP ModPower
- GEC Alstom
We can assist you in developing and implementing a safe management procedure (SMP) for your LV/HV infrastructure and implementing regular inspection and maintenance programmes in line with the relevant Australian Standards.
POTENTIAL FAILURE CONDITIONS
EQUIPMENT FAILS OPEN
In this scenario the switchgear operates correctly to clear a fault and protect the installation however due to a previously unknown issue, or just general wear and tear, the switchgear cannot be reclosed and the installation is unable to be re-energised.
As a result the installation has no power from the normal (ie. electricity network) supply until the faulty equipment can be repaired or replaced.
EQUIPMENT FAILS CLOSED
This scenario is potentially much more dangerous and can result in considerable damage to the installation. In this case a fault occurs in the electrical system and the switchgear fails to operate and clear the fault. In a worst-case scenario this can result in a “bolted-short-circuit fault”.
A 2MVA transformer, such as you might find in the basement of a typical multi-story office building or medium to large shopping centre, is capable of delivering 2 000 000 joules of energy per second. That’s roughly the equivalent of 8.5kg of TNT.
Testing and maintenance is typically carried out in accordance with the guidelines provided by the manufacturer. In most cases switchgear is recommended to be serviced every 2-3 years depending on the installation conditions.
A “best practice” approach of 12 monthly service in conjunction with a building or plant “black out” test is common.
LV ACBs are switched off and withdrawn from the mounting carriage fixed into the switchboard. Some ACBs are bolted directly onto the bus bars and cannot easily be withdrawn for service, in this case it may only be possible to perform testing and not maintenance.
Most often medium and high voltage switchgear and transformers are owned and maintained by the network operator (Western Power) however that is not always the case. If the building owns the MV/HV assets then the building owner has a duty to ensure they are properly maintained.
A High Voltage Safety Management Plan should be implemented, switching programs formulated and a regular maintenance program implemented based on the manufacturer’s recommendations.