Transformer remote control 1

[HamidEle]

There is a discussion going on in regards to whether or not we needs to add a remote control ( PLC start/ stop through 4.16KV Contactor) to the transformer ( 2MVA 4.16KV/600V).One of concerns from one of our electrical guys is the safety. There is a 600V circuit breaker on the sencodnary of the transformer. In my opinion, there should not be any issues as long as no motors would be truned on automatilly after the energization of the tranformer. Moreover, all the maintenance perosonnel will be protected by the arc flash protection schemes. I would appreciate it if anybody can shed some light on me.

 

[rhatcher]

HamidEle,

How do you start the transformer now? If it is the pushbutton on front of the 4.16KV contactor cabinet, then I would think a remote control would be safer. As well, if the electricians are concerned that someone may remotely start the transformer while they are performing maintenance, this would be prevented if they followed common lock-out procedures.

If you give more detail about your situation, I am sure that someone here can offer good suggestions.

 

[Zogzog]

We have remote switching devices for over 100 different applications, including many MV disconnect switches. What is the device feeding this transformer?

 

[HamidEle]

We will start the transformer by on/off buttion on SWGR Contactor cabinet. 4.16KV SWGR is feeding this transformer.Could you elaborate a bit more about the common lock-out procedures? WOuld we have to add additional devices for these procedures?

 

[Zogzog]

Could you be more specific about the type od 4160V switchgear?, thats a pretty broad description.

 

[rhatcher]

HamidElec, how do you 'turn on' the transformer now?

Do the concerns from the electricians about safety come from the existing system or are they concerned about the new system you propose?

To answer your question about 'lockout procedures', most 4160V switchgear has provision to open a disconnect switch and install a padlock to prevent it from being closed again. This is used for maintenance to protect the electricians from accidental turn on of the equipment. The procedure is for the maintenance personnel to install the lock and not remove it until they are done with the work. The lock has only one key so nobody else can turn on the power except the maintenance worker.

 

[HamidEle]

It is a new system under construction. We are to turn on the transformer by local On/Off button or by remote PLC.

 

[racobb]

Just make sure your local lockout disables the the remote control feature as well.

Alan

 

[WhiteyWhitey]

I gather that the concerns of the Maintenance staff is that if the operator were to close the breaker on the transformer there could be someone working on the line. The operator is not aware of the people working on the line and closes the breaker anyway.

(Note: You dont really turn on a transformer you open or close the breaker on either or both the lv and hv side)

To avoid the saftey issue, In my opinion you should have some mechanical lock that prevents the breakers / isolators closing while the equipment is being accessed. This might be done with an lock on an isolator or switch or alternatively, some circuit breaker designs allow the breaker to be opened and then "racked out." removing it from the circuit and any risk of livening up the circuit.

The maintenance works should have a visual break in the circuit that they can confirm onsite is locked from closing onto the circuit they are working on.

Hope this helps, Please elaborate on the situation if i have misinterpreted in some way.

Thanks,
Andrew

 

[ScottyUK]

Any work on HV conductors should have a circuit or busbar earth in place prior to anyone going near the conductors. Simply locking out the switching device good isn't enough for work on conductors, although it is usually acceptable for mechanical work on (say) a pump driven by a motor.

The PLC control circuit should not be relied upon for the safety isolation, and neither should the local control circuit. A positive break in the power circuit, locked open by a padlock or Castell or Kirk key, or by removal of a section of conductor, and a circuit earth through an earthing switch or portable earthing device is required by most safe systems of work.


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