Duty Cycle of 33 kV Circuit Breaker.

Ask the person that designed the system. Auto re-closing isn't something that's done with out careful consideration. And unlikely in a power plant.

The auto recloser is used for overhead power lines that are air insulated / gas insulated, the air/gas being a regenerative insulation. This is the only situation when an auto recloser is used. If the circuit breaker corresponds to a transformer or generator than the auto recloser has to be canceled. Without auto reclosing it won't be O-3min-CO-3min-CO, it will be just O ;) and this is done via the protection relay. When someone says that the circuit breaker has auto recloser it actually means that the breaker is just capable to operate an auto-reclosing cycle. For a breaker to work in the auto reclosing mode it needs a brain - the automation relay/logic to send the electrical impulse for auto reclosing.

tchuss

what dou you mean it will just be O ?? You mean no CO is needed? i.e. since there is no reclose so just open and finished?

As far as I understand, there are two rated operating sequences, defined by IEC and it gives 3 min for time for circuit breakers not intended for rapid auto-reclosing.

1. O-t-CO-t' - CO

2. CO - t" - CO.

sks

Most CB's just open on fault. Auto re-close is the exception to most operating situations. You may have the facility to set re-close in a protection unit, but 99% of the time you don't want it as it would be dangerous!

Yes, there is just "Open" and finished, just as Tony told you earlier . The auto reclosing sequences are attributed to the actuator of the CB because the actuator has to be albe to perform the auto reclosing.

As far as I can tell you still have a lot to learn about power stations, and electrical equipment.

If there is anything else unclear from what I told you just say and I'll try to be as clear as possible in explanations.

tchuss,

nikolay

The concept of '3 min' (t') before the final closing may interest you in the below link:

http://www.energy.siemens.com/us/pool/us/services/power-transmission-distribution/medium-voltage-product-services/tech-topics-application-notes/techtopics61rev1.pdf

thanks friend, but it is all about ANSI/IEEE standards, and nothing to do about IEC standards. We are talking about IEC standad here.

Thanks,

sks