Industrial RCD

Umiq88

Does anyone know what the maximum permitting range is on an RCD when used in a commercial/industrial application.

I have a VSD which is causing a 30mA RCD to trip and I want to change it to an 300mA RCD but I'm not sure if this is permitted.

2011

If the VSD is a fixed appliance (not plugged into a socket) no RCD is required.

Some pieces of equipment such as a VSD tend to trip RCDs due to their design even when operating properly.

M cebee

ya -i think a 30mA rcd may not be compatible with this

DublinDilbert

Has the vsd just been installed or has it been working fine for years.

If the VSD has been working ok for a long time there might be a fault with the cable/motor...

Bruthal

Dont just remove the RCD though if its for socket circuits too. If the VSD is a fixed wired setup but is spurred from a socket circuit then a new circuit would be needed. A socket circuit RCD cant be above the 30ma ones either.

If its already a seperate circuit but wired through the RCD then this can be connected to a non RCD protected MCB once the VSD/motor itself is not just being plugged in.

Umiq88

Its a new installation. The VSD on a mobile unit which is being used from a wall mounted socket outlet. The tripping is normal due to the RFI filter on the drive.

I know that an RCD is not required if the socket is provided for a specific item of equipment. I have also been told that it will operate correctly with a 300mA RCD.

Does anyone know if a 300mA is permitted in an industrical application or is there a restriction and if someone had a reference for this I'd be grateful.

Bruthal

psittacosis wrote: »

Its a new installation. The VSD on a mobile unit which is being used from a wall mounted socket outlet. The tripping is normal due to the RFI filter on the drive.

I know that an RCD is not required if the socket is provided for a specific item of equipment. I have also been told that it will operate correctly with a 300mA RCD.

Does anyone know if a 300mA is permitted in an industrical application or is there a restriction and if someone had a reference for this I'd be grateful.

Once its a socket it requires a 30ma RCD even if its just one socket wired for one item. What would be needed to eliminate needing an RCD would be a spur outlet with the item wired into it, and this would need to be wired back to the board rather than connected to a socket circuit as the socket circuit will need and RCD.

The reason its a 30ma RCD for sockets is to protect people from electrical shocks as 30ma is deemed to offer good protection from dangerous shocks from live to earth, but any lower than 30ma for an RCD would be nuisance tripping too often.

Items that are plugged in and are portable are probably seen as more of a risk than ones permenantly wired into a spur. A 300ma one wont give this same protection from dangerous shocks on portable/plug in items. And if you use a circuit to a spur you wont need any RCD.

2011

General purpose sockets must be protected by RCDs. There are some special purpose sockets that do not require RCD protection in some situations, such as this. Take a look at page 137 of ET:101 4th edition and have a read of 544.4 for examples.

In this case what I would not use an RCD to protect the VSD. I would also do the following:

1) Install a non-standard type of socket outlet so that only your mobile skid can be plugged into this circuit.

2) Have this socket outlet clearly labeled so that it is clear what it's purpose is and that it has no RCD protection.

3) Ensure that the socket outlet(s) for this skid are on dedicated circuit(s)

4) ensure that the skid is in proper working order



Look closely at the earth pin on the example of one type of non-standard socket outlet. Clearly standard plug types can not be used with this.