LO/TO - remote circuit breaker 1

[simonfr]

I am working on a project whereby we shall be providing power from a windfarm to a vessel, so the vessel (if battery) can be charged, or no need to run engines for hotel load when stationary for the night.

The electrical system will be on the wind turbine column (in UK/EU) waters. The vessel collects a cable and plugs it in. No need for someone to go onto the wind turbine to perform switching.

However LOTO would dictate that when the system is deenergised (11kV), the remote circuit breaker must be locked out/tagged out. But no one will be there to physically do this due to its impractibility. So need to satisfy the relevant Authorised Persons.

Is there anything available to perform LOTO on a remote MV circuit breaker, without physically being present? The system shall have a safety PLC and SIL rated system to ensure that it is deenergised, and inoperable until required by persons on the vessel. However the additional layer (LOTO) neeeds to be addressed.

Anyone had a similar conundrum and how did you overcome?

 

[crshears]

simonfr: No need for someone to go onto the wind turbine to perform switching.

Are you suggesting that the cable will be left on potential from the wind turbine at all times?

I'm used to the cable being off pot while the connections are made, at which point the supply and load end breakers are closed to first pot the cable, then place it on load. This would suggest to me the need to be able to operate the Wind Turbine Column breaker wirelessly, using a control and status reporting system that is both dependable and cyber-secure.

Relying on a LO/TO without any one actually attending the WTC to perform it is not something I can see myself ever being comfortable with, especially if it's going to be me with my hands on the conductive parts. Perhaps there are individuals who would accept two open devices in series where the work protection holder can apply passwords to the cyber-secure control system such that operation of either device is impossible until released by the holder . . . but I'm not one of them.

 

[waross]

Yes remote computer control is foolproof. ???
I remember an incident where a fool proof computer control was used for safety lock-out.
An operator spilled coffee on his keyboard and two workers went to the hospital suffering from H²S exposure.

Add a safety disconnect at the end of the cable.
It is a mistake often made by young engineers,
Don't try to justify an unsafe system.
That approach has cost too many lives.

 

[dpc]

You can add a local disconnecting means or send someone to lock out the remote breaker if you really want a true lockout. If you go with a remote lockout I'd also add shorts and grounds locally. I think this is one of those questions where you already know what the answer is.

 

[simonfr]

Are you suggesting that the cable will be left on potential from the wind turbine at all times?

No, the cable will be earthed at all times until plugged in and power is demanded. However the operator(s) on the vessel doing the plugging in, althought the control system/safety system will ensure the breaker is earthed via multilayer protection. No-one will be on the wind turbine to physically the attend breaker.

One possible option is to set a camera at the breaker to physically see if the breaker is in the earth position via the remote station. This would see if the breaker locking pin is engaged, and shows earthed position.

 

[Gr8blu]

Not sure - but the AHJ might be a bit sticky on remote lockout because the requirement is for BOTH lock out AND tag out. That typically means a tag co-located with the lock - regardless of whether there is another tag at the "user" end of the line (near the equipment, or in this case the utility connection point for the vessel). If this is indeed the case, entering the turbine to remove the (interior) tag is likely to be mandatory.

Just a dumb question - is there any way to provide a suitable disconnect/breaker EXTERNAL to the turbine that can be locked and tagged by the vessel personnel - or by maintenance folks attending the tower itself? Refer to IEEE/IEC 80005 series (-1, -2, -3, and I think -4) standards for ship-to-shore connection methods and equipment for various voltage levels and scenarios.