Powermax 45xp lost arc delay (Solved)

rodw wrote:

rodw wrote: I decided to try using my Mesa 7i76e spindle relay while we are exploring this thread but I will post on another thread about that as I had some errors...

Actually I resolved my error and its possibly relevant so I will post here.
I changed my torch on relay to be the 7i76e spindle enable relay. Removed the plasma cutter wires from my relay and connected to TB4-5 and tb4-6. Once I powered up the 7i76e, the torch came on unexpectedly so I switched off the plasma cutter. Then started up in a more orderly fashion and got a startup error from the plasma cutter which is described in the manual

Active Low seemed interesting and I was aware these digital relays are polarised so I swapped the wires around on the 7i76e and it is working perfect.

So I wonder if problems some people have been having using digital relays is becasue they have the wrong polarity?

I'm going to leave it this way and see how it goes...

I did a search for "diode" on each page of the thread after the above was mentioned but nothing came up so I assume the following has not been mentioned.
Components like MOSFET transistors, which is what MAY be used as the "contact" in a SSR relay, or the outputs on Mesa boards, often have an internal diode across them. It's polarity is reversed so that it does not conduct when the MOSFET is wired the correct way. However, when it's wired backwards, it's effectively a conducting diode (i.e. a short circuit or closed switch) across the SSR output. If that is what is causing it then polarity is everything in some SSRs. I won't go as far as saying all SSRs because I simply don't know, but if the output is polarised make sure it's connected correctly.

Keith

Beefy, could you share the map of connections to the Mesa pins and the CPC now you have the correct polarity? It would be good to have a definitive mapping for a Hypertherm machine.

CPC, what's that, Cutie Plasma Cutter maybe

I'm still in the dark ages, not using any CPC connector.

I don't have the polarity yet, not even connected up the plasma cutter, but should be doing it today.

My arc voltage is full voltage, no voltage divider. There are dedicated terminals inside the cutter where you can connect the sensing wires.

I'm using a hand torch at present (despite having a nice Duramax machine torch) and have simply tapped into the torch switch wires, so my torch on relay contact (on my old system) was wired in parallel with the hand torch switch.
What I'm going to do is try measuring the polarity of the Torch On wires from the plasma cutter and match them to the 7i96 output polarity. So if we have wires A and B from the plasma cutter, if A is more positive than B, I'll connect A to the 7i96 +ve output terminal, and B to the 7i96 -ve terminal. Then just for experimenting I'll probably reverse that to see if the torch fires when the output is off, just like what you experienced.

I'll let you know how that goes.

Keith

Hey Rod,

got the plasma cutter firing from the Mesa 7i96. As mentioned last post, I simply checked to see which of the two Torch Fire wires was the positive one, and connected that one to the +ve of the output terminal pair on the 7i96.

Seems to be working like a charm.

Keith