Discuss Air Source pump tripping RCD in the UK Electrical Forum area at ElectriciansForums.net
Hi Marconi, This was the piece of the puzzle it felt like I was missing. The company who were meant to be installing the renewables went AWOL. I had no information beyond the KW loading of the unit and some "monkey see monkey do" instructions regarding the control cables from the water cylinder and heating centre. RA on the day of testing was 11.02 Ohms.I suspect the ASHP's inverter circuitry and associated EMC filter are producing an earth leakage current which may extend to higher frequencies than the mains 50Hz. The first thing to do is look at the ASHP's installation manual to discover what type of RCD is required. Please post full details of the ASHP so we can look up too. A quick way to find out would be to phone the ASHP manufacturer's technical help line.
Here is a short article which gives an introduction to what I suspect is happening:
Heat Pumps – Type F or Type B RCDs? - Electrical Contracting News (ECN) - https://electricalcontractingnews.com/news/heat-pumps-type-f-or-type-b-rcds/
I am not at this stage by showing you the link saying that the solution is a Type F or Type B - we need to look at the manual or contact the manufacturer first.
Note also that one cannot place a Type F or Type B downstream of a Type A or AC so it is likely your ASHP may need a dedicated supply taken from the meter output.
There was nothing in the paperwork that accompanied the ASHP that referred to the supply. Also, when the "engineer" was commissioning the unit, the manufacturer's technical help-line never mentioned the type of RCD, even though they were made aware of the issue.I do not think the Type S RCD has been damaged. The S type may be more sensitive to the waveform of the earth leakage current than the 30mA RCD and thus trips first. Let us know what the ASHP manual says about type of RCD. You tested them I believe and found they operated correctly?
Sure thank you. LG R32 Monobloc.Please send me the details of the ashp and I will do some research.
What is the electrical power rating of the LG unit?Sure thank you. LG R32 Monobloc.
That's all I had to work with!In LG monobloc manual:
Circuit Breaker Specification Perform the electrical wiring work according to the electrical wiring connection. • All wiring must comply with local requirements. • Select a power source that is capable of supplying the current required by the appliance. • Use a recognized ELCB(Electric Leakage Circuit Breaker) between the power source and the unit. A disconnection device to adequately disconnect all supply lines must be fitted. • Model of circuit breaker recommended by authorized personnel Only. • Select a circuit breaker suitable for the current specification.
This is as helpful as LG get!
Hi, Thank you for being so thorough. I do not have access to site and am just setting off on holiday so bare with me. Can you private message on here?What is the electrical power rating of the LG unit?
What is the make and model of type s rcd?
The research I have done does not turn up an RCD type. Indeed, LG literature is silent on any special requirements for type of rcd.
Could you sketch the intake, type S, dbs, final circuits etcetera for me to study please.
I would do some N to E insulation testing of the final circuits If you have not already.
Also, could you measure voltage between N ( at main switch) to E on earth bar with a voltmeter not AVT at no load, light load, medium load and full load? Want to see if N voltage wrt local earth rises by much as loading increases.. Then do an L to E measurement to see how much L falls in voltage with respect to local E as loading increases.
Are you able to temporarily and safely supply LG unit just via its 30mA rcd and mcb ie missing out the type S? Earth to be connected of course.
How long is the final circuit feeding LG unit?
How far away from earth electrode is the LG unit?
Please ramp test the type S RCD when on load apart from LG unit.
Reply to Air Source pump tripping RCD in the UK Electrical Forum area at ElectriciansForums.net
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