If I were to do it all over again, I'd probably try design a solution like that, or something similar (to provide zero-crossing switchover). But for the near term I was hoping that someone might be able to suggest something relatively straightforward that I could add to the existing circuits to suppress the transients sufficiently that my brother can plug the car in and walk away without worrying about tripping the household breaker when the charger changes rates or shuts itself off.How about using Using Opto Coupled Triacs with Zero Crossing Switchover in place of the Relays?
Hi jelliott,
Can you post a schematic of your charging system and let us know about your mains supply and the charging currents/voltages involved?
Hi jelliott,
As far as I know, there are two reasons why a domestic supply will trip:
(1) Excess current
(2) Inbalace between the live and neutral currents
It is also possible that your supply has a ground current trip.
It would be important to determin the cause for tripping before a solution can be suggested.
a. The rate-change relay isn't open before close and is thus shorting
part of the transformer winding. The shorted transformer turn
causes a large current flow (while the relay switches).
b. The rate-change relay flashes over (sometimes) so it's opening
before closing but the opening arc flashes to the other contact
with the same results as (a).
How easy would it be to use two relays with a time delay between them
(and with some sort of interlock too so they both can't be on) instead
of the rate-change relay?
You could try fitting a mains filter like the filters that are fitted to large washing machines.
I don't follow what you are saying here because the objective is to stop transients being fed from the relays back to the consumer unit and activating the trip. The area of which you speak is electromagnetic compatibility (EMC) which covers radiated, conducted and electromagnetic coupling and electrostatic coupling both from the generator and susceptibility point of view.I'm intrigued. At first glance, it seems like it wouldn't be applicable, since these filters are seemingly designed to prevent the washing machine from creating EM interference with other appliances. But I can also see how it might be successful in attenuating the transients that I'm dealing with
Being a Brit, I'm not familiar with GFI outlets so I cant be authoritative, but I cant see that there would be a problem. The filters do not trip the ground current detectors (sensitive type) fitted to some UK domestic installations.Would using one of these filters prevent the car from being charged by a GFI outlet that trips on ground current (i.e. many outdoor outlets in North America)? Hmm...
I don't follow what you are saying here because the objective is to stop transients being fed from the relays back to the consumer unit and activating the trip. The area of which you speak is electromagnetic compatibility (EMC) which covers radiated, conducted and electromagnetic coupling and electrostatic coupling both from the generator and susceptibility point of view.
This type of filter is ubiquitous, being fitted to most electronic and electrical equipment s, in one form or another. In fact, some IEC chassis mount mains inlet receptacles have a similar filter built in, and I know for sure that theses are used in the States.
Yeah, it looks like I can get one of these filters built into an IEC inlet receptacle that's otherwise identical to the on already on the car, for < US$10, so I'm going to go ahead and try it! (But I probably won't get the part in the mail until after the Christmas holiday, so it may be a while before I report back.
The filter built in to an an IEC receptacle will probably saturate (but there is no harm in trying it)- you need a much bigger filter like those fitted to washing machines.
How about adding one zero-switching SSR in place of the shutoff relay and momentarily open that during the relay tap change.
That should prevent any relay arcing or transient surges.
Just go for a filter designed for a higher power inductive load, like a washing machine.I guess I overlooked the relevant parameter(s) when I was shopping around for one of these filters to try--besides eyeballing the physical size of the thing, what should I be looking for to find one with more capacity? Capacitance?
That should work also.I suppose maybe I could turn each of the double-throw relays shown in the above schematic into a pilot relay that switches off one zero-switching SSR and turns on another one.
Here's a rough schematic of the charging system, showing the relays:
View attachment 103081
The mains supply is typical North American 120 VAC @ 60 Hz. The charger provides the vehicle batteries between 5 A (full battery) and 20 A (depleted battery) at ~50 V (depleted battery) to 59 V (full battery) DC.
The breaker in question will not trip on ground current. I don't know definitively whether it's tripping on excess current or on a live/neutral imbalance. But I do know that the breaker trips correspond to the switching performed by the relays, and that their occurrence was reduced by the addition of the SiBOD devices (not shown) between the transformer inputs and the mains power.
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