Earth Leakage in Processing Plant

[Electro-tech]

Hi Guys, Have a problem with a Omron Switch mode power supply & Omron Control Relay Which is only switching a 3phase mixer paddle to stir liquid while in the heating process. The control gear is fed from a single phase supply plugged into a RCD protected socket. The Rcd trips within 9ms @ X1.
I have found that with the cable supply plugged in & not switched on I am getting 45mA of Earth Leakage. The Whole Processing Plant is Stainless Steel Tanks on a gantry. I am assuming that the circuit supplying the rcd has earth leakage & dumping to ground via the supply cable.
Any advice would be much appreciated.Thanks In advance.

 

[marconi]

Sir, this sounds interesting. Could you draw us a diagram of the set up or a send a few pictures of it? And could you add a few more details or descriptions of the fault for us to cogitate on?

 

[PEG]

Hi,with knowledge of the earthing set-up,and due diligence,this should be easy to test.

You need to know,whether this is as a result of compounding design issues,an actual fault,or something unconnected.

If only using an MFT,be careful not to turn it into a giant fuse i recall a pal,destroying a test instrument,with this kind of fault,at one of these micro-brewery things... although,he was a bit numb

 

[Electro-tech]

Hi,with knowledge of the earthing set-up,and due diligence,this should be easy to test.

You need to know,whether this is as a result of compounding design issues,an actual fault,or something unconnected.

If only using an MFT,be careful not to turn it into a giant fuse i recall a pal,destroying a test instrument,with this kind of fault,at one of these micro-brewery things... although,he was a bit numb

Here is a photo of the controls inside the panel sited on top of the tank.
Since posting yesterday I plugged the control panel into a non-RCD socket & everything worked, with earth leakage of 0.6mA. I have also found earth leakage at the main intake of 0.45A. The original supply RCD circuit gives a ZS=1.0 . I am thinking now that circuit was linking the metal tank & gantry to ground. If this metalwork is not bonded to the Supply MET then earth leakage current would flow to that ground point. I am thinking from memory that with High integrity earthing above 10mA you can fit a BS EN 60309 Plug & socket outlet. Also a Risk assessment I guess. I will check the bonded of the metal Tank & gantry first. Thanks, guys so far.

 

[PEG]

Hi,what is the liquid? Is the control equipment rated for it's environment....are things steamy and gloopy?

 

[Electro-tech]

ed

Hi,what is the liquid? Is the control equipment rated for it's environment....are things steamy and gloopy?

The liquid is cleaning detergent-based products diluted with water, the tank has a lid. The control panel is metal with a weatherproof lid that locks. I know where you are going but everything is working fine on a different none - RCD circuit. I would prefer to put supply back on RCD but need to deal with the Earth Leakage on the original supply.

 

[marconi]

Studying the vs mini j7 which is a three phase inverter it looks odd to see top left blue, grey and brown going to the three line terminals and black to the earth terminal. These conductors all come from the black sheathed cable. Something wrong? Why is there not a greensand yellow to earth terminal and grey, black brown to line terminals? Someone made a mix up with new wiring colours?

 

[Electro-tech]

Studying the vs mini j7 which is a three phase inverter it looks odd to see top left blue, grey and brown going to the three line terminals and black to the earth terminal. These conductors all come from the black sheathed cable. Something wrong? Why is there not a greensand yellow to earth terminal and grey, black brown to line terminals?

Thanks for that, As I had to get it working quickly I had not had the time or access to the equipment but now is working I will look next machine downtime or the weekend when closed. I will update if I find anything strange.Thanks again.

 

[PEG]

I would assertain,that it is an earth leakage,and not an IR problem.
The shut-down would be an ideal opportunity,for this ?

 

[FarmersFriend]

How are the output cables from the VSD screened, I’ve had multiple issues with SY cable screen bunched into a tail rather than glanded with the correct glands that have cause all sorts of problems.

 

[sparkey999999]

Some old VSD's suffer from a large internal leakage and can not be operated from a 30mA protected supply

 

[Electro-tech]

Some old VSD's suffer from a large internal leakage and can not be operated from a 30mA protected supply

Thanks, guys for the information, I have not had a chance to look at yet, maybe this weekend. I will let you know. Cheers!