earth leakage rating for 63 amp 400V socket outlet
earth leakage rating for 63 amp 400V socket outlet
(OP)
We have numerous 63 amp socket outlets, 400 3 phase VAC (50Hz) for powering fans etc in our plant. Traditionally they are protected by overcurrent MCBs which have integral earth leakage protection (RCD) rated at 30 milliamp.
Our national wiring regulations stipulate EL protection for 16 amp 230 volt socket outlets however there is no stipulation for 400 volt systems.
I wish to replace these 400V EL units from 30mA to a higher rating because we experience a lot of spurious tripping.
Any thoughts on this?
Our national wiring regulations stipulate EL protection for 16 amp 230 volt socket outlets however there is no stipulation for 400 volt systems.
I wish to replace these 400V EL units from 30mA to a higher rating because we experience a lot of spurious tripping.
Any thoughts on this?






RE: earth leakage rating for 63 amp 400V socket outlet
If the branch circuits are tripping at 30 mA that's about 20 Watts of loss. That seems a little high.
The nuisance tripping may be signalling you that the fan motors are approaching the end of their insulation life.
I would first check the leakage current on the circuits with the fans connected and with the fans disconnected.
If this is a new installation, with very long branch circuits, you may have capacitive charging issues. If the current is capacitive and spurious tipping has been an issue since new, your options may be to change the branch circuit conductors for conductors insulated with a material with a lower capacitive constant, reduce the length of the branch circuits with the installation of sub panels closer to the loads or the installation of small reactors on each circuit to divert the capacitive current from the trip units.
I would only increase the trip settings as a last resort and after an investigation of the cause of the tripping.
Bill
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"Why not the best?"
Jimmy Carter
RE: earth leakage rating for 63 amp 400V socket outlet
If that doesn't help, an isolation transformer may be needed.
There are motor inverters with sine-wave output. They have very low capacitive leakage and have been used with cable lengths like 300 meters without problem.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: earth leakage rating for 63 amp 400V socket outlet
The motivation in that case is because all sorts of funny things in various states of development are plugged into those outlets, and only by authorised, competent people, a higher trip level makes a significant dent on nuisance tripping.
RE: earth leakage rating for 63 amp 400V socket outlet
My sockets are 63 amp 3P+E as they supply motors only.
Generally MCCs feeding motors do not have earth leakage protection, although they do have earth fault protection in larger motors.
I am busy trying to get a recommendation from M&G on what ELUs (RCDS) to use.
MY original question also relates to the fact that we are using 3P+N RCDs and NOT supplying a neutral, so will this cause problems.
In answer to Waross, these fans are fairly new.
In answer to Skogsgurra, these outlets are not supplying VSDS just 3kW 400V 3 phase DOL motors.
There ARE four large VSDS inside the same substation though.
Thanks for your thoughts gents.
RE: earth leakage rating for 63 amp 400V socket outlet
RE: earth leakage rating for 63 amp 400V socket outlet
The authoritative sources in Oz are the workplace health and safety laws, made accessible by Safe Work Australia, and the standard "AS/NZS 3000 Wiring Rules" which is mandatory under those laws.
Not having a neutral is not a problem for RCD operation. The RCD's test circuit however, does need to be suitable (no big deal, just a couple of ways to do it).
RE: earth leakage rating for 63 amp 400V socket outlet
RE: earth leakage rating for 63 amp 400V socket outlet
It looks like you are from the "IEC world" where your installation code is IET Wiring Regulations for Buildings 17 th edition (BS7671) or a local code based on IEC60364 and your LV earthing method is TT.Per IET Wiring Regulations,all 230 V socket outlets have to be provided with 30mA or less RCCDs for human protection. Because these 230V outlets are mainly used in houses,offices by unskilled ordinary people.Now 400 V outlets are mainly for indutrial use where welding plants,portable pumps etc are connected and use.Per IET Wiring regulations the earth leakage protection for these 400V circuits can be provided by overcurrent devices for TT earthing method.One should expect small leakage currents from the equipments connected to these 400V outlets, and therefore if you install RCCD devices for earth leakage protection, then it will give nuisance tripping.Therefore,in my opinion, (1) provide earth leakage protection by 30mA RCCDs for 230V outlets (10mA for swimming pools)as you have already done (2)No need to provide earth leakge protection using 30mA RCCDs for 400V outlets.But make sure that the overcurrent devices connected to these 400V circuits DO provide adeqaute earth leakge protection by measuring/ testing the earth loop impedance (Zs).Hope this helps.
RE: earth leakage rating for 63 amp 400V socket outlet
RE: earth leakage rating for 63 amp 400V socket outlet
Why do you assume a TT installation?
I just assumed it to be TT because most of the eastern countries are having TT.
Anyhow even if the earthing system is TNCS or TNS then both 400V & 230V outlets can be easily provided with earth leakage protection using OCPDs subjected to the condition that it satifies the loop impednace given in 17 th edition.
RE: earth leakage rating for 63 amp 400V socket outlet
RE: earth leakage rating for 63 amp 400V socket outlet
Kirbanda spot on with your observations. I deliberately do not refer to socket outlets because we are NOT supplying them via this 4 pin 63 amp sockets. We mostly certainly do have extremely strict wiring regs and all 230v 16 amp socket outlet must have 30mA EL protection, not negotiable. I can remember doing 16th Edition in the UK back in 1998, I think it is 17th or even 18th now. In those days socket outlets did not require RCD by law but it has probably changed now.
Scotty I am in South Africa. I spent 9 years in the UK so I got pretty familiar with the various regs you have there. Many if not most electrical and safety regulations in South Africa have been adopted over the years from British and European standards especially in mining industry where I used to work.
many thanks for assistance chaps.
RE: earth leakage rating for 63 amp 400V socket outlet