12 kv RETROFIT TYPE VCB
The operation and performance of any switchgear is important to minimize the shut down period and this totally depends on:
1.Need for maintenance
2.Frequency of maintenance
This totally depends on the technology utilized.In the switchgear basically except circuit breaker all other components are stationary. The circuit breaker is only operated as and when required.
The maintenance of conventional circuit breaker i.e.ACB/BOCB/MOCB requires periodic maintenance/replacement of contacts, quenching medium such as oil and the spares for operating mechanism. The frequency of maintenance of ACB/BOCB/MOCB is dependent on no.of short circuit operations and the switching applications.
In our country the installation of switchgear started with ACB/BOCB/MOCB and these arrangement are in service more than five decades. The switchgear need large amount of spares and since last few years the manufactures have gradually tapered off the the production. This resulted in retrofitting of old ACB/BOCB/MOCB switchgear with VCB, which is the best alternative for the old installations. The main advantage of retrofitting is investment cost of upgrading is kept bare minimum besides less down time in the existing plant.
Advantage of Retrofitting:
1. It is cheaper and simpler alternative to enhance the life for the old installation whose service life in almost over or even surpassed.
2. The benefits of modern technology viz. vacuum technology can be made available with minimum installation cost.
3. The frequency of maintenance of can be drastically reduced as VCB used in place of ACB/BOCB/MOCB.
4. There is no need to store large quantity of costly spares of ACB/BOCB/MOCB
which may not be availabe because its manufacturing has become obsolete.
5. Since ACB/BOCB/MOCB manufacturer's has stopped manufacturing the breakers, their spares may not be availbale and even if purchased from the supplier other than the manufacturer's one may not get genuine spares.
The retrofit is simple and cost affective in implanting the new technology. The following things has to be taken care of during retrofit.
1.Decide the current rating and fault level required.
2.Matching the power isolation contacts.
3.Confirming the interlock required as per current statutory requirement.
4.Ensuring the rigidity of Bus/Jumper support for the required rated current/fault
5.Ensuring the vermin proofing.