Quite often we face problem that as soon as auto synchronizer give command to close the generator breaker, one relay contact is burnt which is responsible to pass dc supply to energize the generator closing coil and is in series with.

Appreciate if the possibilities are highlighted on the causes of burning that particular relay contact, responsible for generator breaker closing.

Thanks.

 

Shams,

Without MUCH MORE information we can't be too much help, and we a would really need to see the circuit drawing for the breaker close coil to be most helpful.

It would also be very helpful to know specifically which relay is experiencing the burnt contact.

We don't know anything about the control system, the synchronizing equipment and the interlocks in the breaker close coil circuit at your site. We don't know if this problem has been present since commissioning or has devoped more recently, such as after some kind of maintenance was done on the generator breaker or some change was made to the breaker close coil circuit. This mind of information is key to diagnosing a problem such as this--actually it's very important to diagnosing most power plant problems.

However, many generator breaker close circuits use a normally closed contact from the generator breaker to interrupt (open) the current to the close coil when the generator breaker closes. This contact should be from what's called a direct-acting mechanism on the breaker itself--NOT from an auxiliary relay.

If this contact does not open quickly enough sometimes the current being applied to the close coil can burn some more delicate contacts.

Also, sometimes the breaker closing mechanism can wear over time and require more force--and hence more current--to initiate the breaker closure. It would also be helpful to know more information about the type and manufacturer of the breaker to be of more help.

But, someone needs to review the electrical close coil circuit and understand the various interlocks and ensure they are all working properly. Also, the breaker just may be overdue for maintenance or require repair.

But that's about the extent of the help we can offer based on the information provided. Hopefully we have to given you some helpful information and pointed you in a direction that ultimately helps to resolve the problem.

Please write back to let us know how you resolve the problem!