3 phase RCCB. Where to Buy?

[carlyai]

I'm looking for two A9Z21425 Acti9 ilD 4P 25A RCCB's.

Sompar company is looking for me, but no success at the moment.

My Consumer Unit is the Schneider plug-in type.

Anyone know where I might get these breakers?

[Crossy]

You do realise that's a DIN mount unit not plug-in don't you?

 

https://www.tme.eu/en/details/a9z21425/rcd-circuit-breakers/schneider-electric/

 

 

[carlyai]

23 minutes ago, Crossy said:

You do realise that's a DIN mount unit not plug-in don't you?

 

https://www.tme.eu/en/details/a9z21425/rcd-circuit-breakers/schneider-electric/

 

 

Yes I realise it's a DIN mount, but I want the breaker with a plug in mount as in the pic.

Thanks.

I can't seem to find the RCCB with a plug-in mount, though there are 3 phase breakers with plug-in mounts, but can't find a RCCB.

[Crossy]

Yeah, plug-in 3-phase rcd/rcbo are as common as hen's teeth, mcb's no problem at all of course.

[carlyai]

3 hours ago, Crossy said:

Yeah, plug-in 3-phase rcd/rcbo are as common as hen's teeth, mcb's no problem at all of course.

Yep.

So I could maybe install 6 Plug-in RCBO's or make up 2 DIN boxes with DIN RCCB's. Not as nice as finding the correct Plug-in.

Explanation:

I have two 3 phase multi-point instant hot water services. They are wired as per installation instructions both earthed. 

I'm slowely replacing breakers I think should be earth leakage trip and would like to replace the 3 phase MCB's for the water heaters.

 

[Crossy]

22 minutes ago, carlyai said:

So I could maybe install 6 Plug-in RCBO's

 

You can't use 3 x 1 phase RCBOs instead of a 3-phase unit I'm afraid

 

How will you route your single returning neutral, or, if the heater doesn't have a neutral your 3 x 1 phase units will never see balance and won't stay on

 

I suspect that your only solution, if you don't want to replace your plug-in CU, would be to add a separate box with the 3-phase DIN units in it.

 

Note: - Even if your heater is 3-wire your RCDs will likely need a neutral connection on the inlet side.

 

@bluejets have you ever seen a plug-in (Schneider) 3-phase RCBO? This would be to protect a 3-phase load (water heater) and replace a 3-phase plug-in MCB.

[carlyai]

I contacted Schneider Electrics Australia and they said there is only the RCCB 3 phase DIN  connector type.

There must be a reason Schneider make the plug-in module CU, they make a 3 phase plug-in MCB, but not a 3 phase RCCB.

Placed back in the 'In Hand' basket.

[carlyai]

1. I worked out why they don't make plug-in 3 phase RCCBs. The main Plug-in box breaker can be a MCB or RCCB. 

2. Question for @Crossyor anyone please.

You said I can't replace a 3 phase RCCB with 3 single phase units; can you explain please?

My 3 phase instant heater has no neutral and uses 2 phases on low heater power and 3 phases on full heater power.

If each single phase RCCB has an active and neutral, and neutral tied to the CU neutral buz, won't the phase current of that breaker be the same unless an earth fault?

Sorry for the trouble.

 

[Crossy]

OK I'll try and keep this simple.

 

An RCD is sometimes called a differential circuit breaker.

 

In a single-phase application it checks the difference between the L and N currents (effectively it sums the currents) and if the difference is greater than the trip current (say 30mA) the breaker operates cutting off the supply.

 

A 3-phase unit has to sum the currents in all three phases and the neutral and trip if there's an overall mismatch. BUT it has to do a vector-summation because of the phase angle between the phases. It actually achieves this by the simple expedient of passing all 4 wires through the same sense coil and by magic achieves the desired result (it just does OK, I'm not going to try and give course in 3-phase theory - it's been waaaay too long since I did any).

 

If you try to use 3 single-phase units each of them only sees its own phase current and nothing in its neutral. Major differential, trip.

 

 

 

 

[carlyai]

19 minutes ago, Crossy said:

OK I'll try and keep this simple.

 

An RCD is sometimes called a differential circuit breaker.

 

In a single-phase application it checks the difference between the L and N currents (effectively it sums the currents) and if the difference is greater than the trip current (say 30mA) the breaker operates cutting off the supply.

 

A 3-phase unit has to sum the currents in all three phases and the neutral and trip if there's an overall mismatch. BUT it has to do a vector-summation because of the phase angle between the phases. It actually achieves this by the simple expedient of passing all 4 wires through the same sense coil and by magic achieves the desired result (it just does OK, I'm not going to try and give course in 3-phase theory - it's been waaaay too long since I did any).

 

If you try to use 3 single-phase units each of them only sees its own phase current and nothing in its neutral. Major differential, trip.

 

 

 

 

Yep, got it. Thanks.

I keep forgetting to look at the vectors.

[Crossy]

2 hours ago, carlyai said:

Yep, got it. Thanks.

I keep forgetting to look at the vectors.