RCD protection for portable equipment with Inverters

[gerard]

Hi,

I know this has been covered before and I don't mean to repeat questions. I am looking to get some opinions on a problem I have encountered in the past and have experienced recently. I have a machine with two 3ph motors which are controlled by Inverters. They are 1ph - 3ph Inverters. The problem is they keep tripping the RCB. I tried putting a 100mA RCBO on the circuit, with no success. For this reason, I have taken the RCD out of the circuit and is now only protected by a MCB. I feel very uncomfortable with this and I am looking for similar problems you have encountered and how you solved the problem? The regs do not cover such equipment with Inverters and their protection.

Thanks

 

[netblindpaul]

Check Manuf' instructions.
Why are you so uncomfortable?
RCD's are THE most unreliable protection device that we use.
This is proven by independent authoritative research.

 

[gerard]

I looked at the manufacturers info and I am none the wiser. I feel uncomfortable because I am afraid the machine might become live and give the operators
a smokin' perm! The circuit is only used for this particular machine and not for appliances like Hoovers and floor scrubbers, also, the machine in question is stationary. So, you reckon all is fine and I have nothing to worry about then - no need for a higher rated RCD? What would you do in a similar situation?

 

[Knobhead]

RCD’s and inverterers don’t like each other. I think your on a hiding to nothing, you just have to accept there’s going to be leakage and arrange the supply to suit.

 

[gerard]

RCD’s and inverterers don’t like each other. I think your on a hiding to nothing, you just have to accept there’s going to be leakage and arrange the supply to suit.

Ok, so would you just protect the circuit with an MCB, make sure all connections are sound and forget about it?

 

[netblindpaul]

I feel uncomfortable because I am afraid the machine might become live and give the operators
a smokin' perm!

Why, is there no fundamental protection in the installation in the way of ADS (ex EEBADS?).
You ARE NOT ALLOWED TO RELY ON ADDITIONAL PROTECTION.
An RCD IS ADDITIONAL PROTECTION.
IF you are relying on an RCD, for basic protection then you are non compliant with 7671 & almost certainly EAWR & PUWER.

 

[gerard]

I am only relying on the MCB for protection

 

[netblindpaul]

I am only relying on the MCB for protection

Then your problem is?

 

[gerard]

Well do I have a problem and would you be happy with this?

 

[netblindpaul]

Gerard,
What is your problem, why are you unhappy, I can say anything from here and it would mean nothing.
I am asking these questions for a reason, and trust me please, it is not to be horrible, there is another reason, but there is also the same validity to my asking the questions as to why I am not answering them...
Please think about this and answer my question, I will help, but I can't give you the answer.

 

[gerard]

The machine is plugged into a 16A 1ph socket without RCD protection because of the reasons above. As the machine will not operate with an RCD, I am just concerned about the machine becoming live and injuring (or worse) an operator - that's all.

 

[netblindpaul]

You have perfectly functional and sound ADS on the supply circuit that complies with the current version of BS7671 do you not?
Excluding the RCD for the moment.

 

[gerard]

You have perfectly functional and sound ADS on the supply circuit that complies with the current version of BS7671 do you not?
Excluding the RCD for the moment.

Yes I do.

 

[netblindpaul]

So why do you want additional protection?

 

[Engineer54]

What do you think equipment and machinery relied on for more years than you can remember, or come to that, ...i can remember?? There was no RCD protection available then, RCDs are a relatively new form of protection, that far too many these day's rely on. While they serve/provide a very worthwhile form of protection, they are not the cover all cure protection many think they are!!! As you have found out, sometimes they just don't fit in. They are also not the most reliable bit of kit either, often causing more trouble than they are worth.

So, if you have a proven functioning ADS on the supplying circuit you have a safe installation that has proven it's worth for many many years. So get some sleep tonight!! lol!!!