Page 12 of 13

Re: My L1 ESVE findings.....

Posted: Thu Sep 29, 2011 2:14 pm
by lincomatic
If you can post some high res photos of the depotted board somewhere, maybe we can help you trace the board.

Re: My L1 ESVE findings.....

Posted: Thu Sep 29, 2011 2:59 pm
by chris1howell
As for the hot path, there are some tvss diodes that I'm not sure if they are good up to 240 or not. My guess is that they are not. One typically wouldn't design a circuit for 120VAC and use 240VAC TVSS diodes. They probably wouldn't do their job at 120 if they were spec'd for 240. And if overvoltage was applied to these diodes rated at 120 they would constantly be trying to short the excess energy to ground which would ultimately blow them up since they would be shorting all the time.
If there is a diode is going from L1 Hot to Ground and L2 Neutral (or Hot in the case of 240) to ground than the total potential is 120V on each leg regardless if you are at 120 or 240...

J1772 recommends, if possible, to have TVSS protection on the ESVE end as well. The best way would be to add a third AC path with a third relay and another set of TVSS protection diodes from the second leg to the neutral as well. Then both are protected with respect to the neutral which should be at ground potential.
J1772 recommends a TVS diode on the pilot (12V DC), on both the EVSE and EV. There is no mention of TVS on the high voltage path...

I am not sure where you are going with the third relay and third path, none of the L1/L2 or L2 only EVSEs implement this arrangement. There is no problem with the Hot Neutral Ground in the case of 120V or Hot Hot Ground for L2.

Re: My L1 ESVE findings.....

Posted: Thu Sep 29, 2011 3:39 pm
by lincomatic
chris1howell wrote:
If there is a diode is going from L1 Hot to Ground and L2 Neutral (or Hot in the case of 240) to ground than the total potential is 120V on each leg regardless if you are at 120 or 240...
Currently, it's going from Hot to Neutral, 120V. But if one were to connect the 2nd Hot for 240V to the wire that's currently Neutral, then there would be 240V across these wires.
chris1howell wrote:
J1772 recommends, if possible, to have TVSS protection on the ESVE end as well. The best way would be to add a third AC path with a third relay and another set of TVSS protection diodes from the second leg to the neutral as well. Then both are protected with respect to the neutral which should be at ground potential.
J1772 recommends a TVS diode on the pilot (12V DC), on both the EVSE and EV. There is no mention of TVS on the high voltage path...
Right, the only place transient protection is shown on the EVSE side is Fig A1 of the J1772-2010 spec, on the pilot (it also shows it on the EV side). Figs 3 & 4 show it on the EV side of the pilot, but nothing on the HV circuit. The description in A1.1.e where they recommend the TVS on both EVSE & EV is referring to the pilot. Are you sure the TVS is on the HV circuit?

Re: My L1 ESVE findings.....

Posted: Thu Sep 29, 2011 3:49 pm
by chris1howell
Currently, it's going from Hot to Neutral, 120V. But if one were to connect the 2nd Hot for 240V to the wire that's currently Neutral, then there would be 240V across these wires.
Thanks lincomatic, so it looks like we have identified a required modification....

Re: My L1 ESVE findings.....

Posted: Thu Sep 29, 2011 7:24 pm
by garygid
Apparently this change is part of Ingineer's modification: using a 240v part (about 400 or 450v peaks?) instead of a 120v part (200 to 225v peaks?).

Re: My L1 ESVE findings.....

Posted: Fri Sep 30, 2011 7:26 am
by jwallace3
Yes, you are both very right. Just looked back at the spec. I will take a look tonight and double check. I'm still tracing out the DC path and control path. I'm about 50% done there. The power supply in this device is pretty simple. Like second year engineering school simple. Transformer steps it down to 20.90VAC which goes through a bridge rectifier, smoothed out by an electrolytic capacitor and then to a 12 volt regulator, which also feeds a 5 volt regulator.

As far as why am I still proposing a third path? Just so you don't have to upgrade the board if you didn't want to.
lincomatic wrote:
chris1howell wrote:
If there is a diode is going from L1 Hot to Ground and L2 Neutral (or Hot in the case of 240) to ground than the total potential is 120V on each leg regardless if you are at 120 or 240...
Currently, it's going from Hot to Neutral, 120V. But if one were to connect the 2nd Hot for 240V to the wire that's currently Neutral, then there would be 240V across these wires.
chris1howell wrote:
J1772 recommends, if possible, to have TVSS protection on the ESVE end as well. The best way would be to add a third AC path with a third relay and another set of TVSS protection diodes from the second leg to the neutral as well. Then both are protected with respect to the neutral which should be at ground potential.
J1772 recommends a TVS diode on the pilot (12V DC), on both the EVSE and EV. There is no mention of TVS on the high voltage path...
Right, the only place transient protection is shown on the EVSE side is Fig A1 of the J1772-2010 spec, on the pilot (it also shows it on the EV side). Figs 3 & 4 show it on the EV side of the pilot, but nothing on the HV circuit. The description in A1.1.e where they recommend the TVS on both EVSE & EV is referring to the pilot. Are you sure the TVS is on the HV circuit?

Re: My L1 ESVE findings.....

Posted: Fri Sep 30, 2011 7:28 am
by jwallace3
I checked for this resistor. It's actually 2k. So it should have been .06 amps. Is this an analog ammeter you were using?
lincomatic wrote:I did some testing of the ground integrity check w/o opening mine up. I connected the ground pin of the EVSE to an earth ground (a screwdriver driven into the dirt) instead of the house ground. It still passes the ground check and works normally, even though the impedance between neutral and gnd is very high, so this rules out the idea that it's checking the for neutral shorted to ground. My ammeter shows that there's a constant ~0.6A (sounds high to me.. but my two ammeters had the same reading) current running from hot to gnd. It checks the ground continously... if you disconnect it, the green ready light blinks, and when you reconnect the ground, it goes solid again.

So.. since it doesn't try to short neutral to gnd, and *if* there's nothing in the hot path through the relays that can't handle 240V, I think it should work on 240V with a power supply that steps it down to the 20V that the control board needs.

Some questions from the photo's I've seen of the insides:
1) Why is the small relay for GFI trip test 13A? Isn't that overkill?
2) Why is the fuse 25A when the main relays can handle only 20A, it's supposed to be used on a 15a circuit, and have 12A max current draw?
3) If it has a 25A fuse, why didn't the fuse blow when Ingeneer did the 26.5A smoke test?

Re: My L1 ESVE findings.....

Posted: Sat Oct 01, 2011 11:08 pm
by lincomatic
jwallace3 wrote:I checked for this resistor. It's actually 2k. So it should have been .06 amps. Is this an analog ammeter you were using?
I used two different DMM's. Sorry, I read the scale wrong. It's actually .6mA. The line voltage was 119V. The voltage from the EVSE ground pin to house ground was 56V. So the resistor should be more like 100K.

Re: My L1 ESVE findings.....

Posted: Tue Oct 04, 2011 7:59 am
by jwallace3
You may be correct. I had the wrong pin connected when checking myself. 2k is the resistance from ground to the pilot pin.
lincomatic wrote:
jwallace3 wrote:I checked for this resistor. It's actually 2k. So it should have been .06 amps. Is this an analog ammeter you were using?
I used two different DMM's. Sorry, I read the scale wrong. It's actually .6mA. The line voltage was 119V. The voltage from the EVSE ground pin to house ground was 56V. So the resistor should be more like 100K.

Re: My L1 ESVE findings.....

Posted: Wed Oct 26, 2011 7:57 am
by jclemens
Has everyone given up on this?
or is there already info out there on how to use 240V?