120VAC ignition coil

udtwmc · Jul 3, 2021

Hi from the U.K.

I have a U.S.A. 120VAC 60Hz ignition coil (made by Carlin Combustion, model 45000 proX… the data sheet says the high voltage secondary coil is mid-point grounded).

I have been powering the coil from a U.K. 115VAC 50hz supply (my supply has one leg of the transformer grounded to earth so 0-115VAC).

it’s been working ok for a few weeks but has started tripping out the circuit breaker.

there’s a number of possible reasons why, but first I’d like to eliminate the possibility that my ‘end-grounded’ 115VAC supply isn’t burning it out!

I understand America has two voltage option fir your supplies, you have a 240VAC centre-tapped transformer with two hot wires (red and black = 240V) with a white neutral centre-tapped from the secondary transformer and grounded to earth (so red + white = 120VAC and black + white = 120VAC)

so my UK supply is effectively the same as using your red and white cable. What I’m not sure about is whether the ignitor’d primary side is also centre-tapped in which case I would be shorting out one side of its primary coil and burning it out. But If the ignitor data sheet only means it’s secondary coil is mid-point grounded I shouldn’t have a problem, no?
Any suggestions?
Cheers

ControlsEngineer · Oct 22, 2021

Hi from the states.

I may be misunderstanding your terminology, but in the US we have 208 single/three phase. This is 2 or 3 hot phases with a shared neutral. This is almost across the board for all residential. Any single phase gives one ~115 - 120 VAC to neutral/ground and ~200 - 208 VAC phase to phase on any 2 phases. Most residential panels have a jumper from neutral to ground. If one adds a sub-panel, then that panel has to be grounded back to the source and depending sometimes a ground rod. The neutral and ground are NOT jumped together in the sub-panel. Very few residences have 3-phase
240 VAC that I have had experience with in the US is 3-phase and is a "center tap delta" configuration. 2 of the hots ("A" phase OR "C" phase) to neutral/ground are ~120 - 125 VAC, and 240 phase to phase on any 2 phases. HOWEVER, if the service is wired to code, "B" phase is ~190 VAC to neutral/ground. This is called a "wild leg" , "high leg" by most electricians in the US and is supposed to be marked orange or red by code.
In your situation, I would see if you can find a manual for the coil and check the voltage. I've seen loose neutrals cause problems, not necessarily burn-outs but intermittent problems.
I probably got a little off track here however I hope this helps.

Avo Mk8 · Oct 22, 2021

Hi
If this set up is in the UK, there shouldn't be any connection of anything in the live/neutral circuit to 'ground'.
But OK for the ignition high voltage secondary centre tap to be grounded, only if isolated from the primary.

Maybe I'm misunderstanding what you are saying about your transformer wiring, but .............

If your 115v transformer is an isolating transformer, and you have connected one side of the secondary to ground, that's OK, but I would have been inclined to leave it floating.

If your transfomer is an autotransformer, i.e one single winding, with a tap for the 115v, you should not be 'grounding' any of the winding connections.

In the UK both live and neutral connections are regarded as 'live', or conceptually 'hot' in US parlance, although there's normally not much potential difference between neutral and ground. You are not permitted to connect neutral and ground together within the house wiring.
Is it a RCD that's tripping, or a MCB?
If RCD, is it because you've connected the neutral of your transformer to ground?

Apologies if I've misunderstood your references to grounding the leg of the transformer!?

Lucien Nunes · Oct 22, 2021

A USA 120V supply is conceptually identical to a UK 230V one. A grounded neutral and a hot (line) wire. This is the correct supply for the ignitor module, so you seem to be powering it correctly. Ignition transformers are invariably isolating, not auto.

There will be no direct connection between any part of the primary circuit and ground, however the module might however contain suppression components such as VDRs in this location. Incorrect voltage, or voltage to ground on the neutral wire, might cause them to break over and/or ultimately fail. So it would be worth checking the polarity and actual voltage under operating conditions before replacing.