[dynasty200sd]

On my Miller Dynasty 200SD, I can set the machine to initiate the arc with either electrode positive or electrode negative when welding in A/C. What factors in deciding whether to start the arc in EP or EN?

[Otto Nobedder]

On my Miller Dynasty 200SD, I can set the machine to initiate the arc with either electrode positive or electrode negative when welding in A/C. What factors in deciding whether to start the arc in EP or EN?

I'm going to take a stab, and say the difference is material-specific. For aluminum. particularly anodized, an EP start would make sense to break the oxide layer. In an aluminum-bronze TIG-braze, one might wnat the heat to hit the joint hard, first.

These are guesses, only, and I await anyone with a solid answer.

Steve S

[angus]

not an answer but I am wondering why, if you are in ac, you would do more than set you en/ep balance. it's ac.

as far as breaking through the oxide layer, you would use, preferably, a rocker switch/momentary contactor or foot pedal and if need be your ac balance adjustments (if that feature is even available on the machine you are using).

[Braehill]

@angus,
His machine must have balance adjustments if it's asking which half of the AC wave he wants to start in.

That should all take place in a single hertz in the initial arc strike, if I understand this setting right.

Len


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[zank]

The miller reps I've spoken to have said you always want to set the start on EP for AC. You get much more consistent starts that way.

[admin]

I believe it's possible to get better crisper starts at low amperage by setting the start mode to ep. In fact the first generation Lincoln invertec v205t stArted in ep for a few milliseconds even when set on dcen. It rounded the tip a bit but started well at low amps on dcen without melting even really thin material.

Lincoln since figured out how to get good starts on dcen.

Anywho, ep makes the tip of electrode heat up quick and therefore allows an easy start on ac

Jody


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