hook up rotary converter

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Posted · Report post

Hi all, I am trying to figure out how to hook up a rotary phase converter to a 240v 7 1/2hp 3 ph motor on powerhammer. I would like it to be running before being able to turn on the machine. I have have only the one machine so I usually turn on converter and then the machine but sometimes forget the converter is not running and hit the machine on and it is not happy.
I was thinking of using the generated leg of the rotary to power the pushbuttons for the machine so if the rotary is not running then nothing would happen by pushing the start. Stupid idea? Is there a better way?
Thank you
Rob

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Posted · Report post

I may be a bit out of my league here and not explain this using proper terms but I think if you use the leg generated from the phase converter as the leg that makes the mag switch engage you will get the results you are looking for. So ya, it seems like your idea will work....

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Posted · Report post

Fe,
That is the idea exactly, but I am not sure the voltage of the third leg is steady enough to not hurt the coil on the mag starter. I don't want do do something that could be hazardous to me or the equipment. I need to check the voltage of the third leg with and without the machine running.
Rob

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Posted · Report post

Your phase converter may say what the devaluing of the output voltage is. from what I understand, mag starters work within a voltage range also specified on the mag starter label. My only concern for witch I have no experience is if the phase converter can leave the output leg hot depending on where it stops in the rotation when turned off but then if it is truly static then that shouldn't be an issue... thinking out-loud here.... Also, it may not be so much an issue of voltage- rather the amps...

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Posted · Report post

If we get a break in the weather I will go out and check to see what the third leg is and if power is transmitted to it if stationary.
Rob

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Posted · Report post

Generally it is a no-no to use the generated leg of the phase converter to power the controls of anything.

The third leg will generate ~ 240 vac between it and ground. It does not split to 120 vac like your household current does.

Some folks call this a stinger.

Does your hammer try to single phase when the converter is off?

The hammer shouldn't even have any power going to it unless the converter is running.

Did you build the converter?

Hope this helps.

Zach

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Posted · Report post

Tormented-The hammer has single phase to it when converter is not running, that is the problem. The 2 hot legs come into the converter are tied to two of the three legs going out plus the generated leg. It is a purchased static with an old motor for the rotary and I am sure it is hooked up the way the converter company wanted it. I didn't think of doing it another way at the time but now it would be nice not be able to turn on the hammer without the converter running.
Rob

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Posted · Report post

Using a relay to engage the controls when the 3ph power is active is the correct way to do this. It is not to code to tap a single phase off the converter for your control voltages.

just an FYI from a real electrician

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Posted · Report post


Using a relay to engage the controls when the 3ph power is active is the correct way to do this. It is not to code to tap a single phase off the converter for your control voltages.

just an FYI from a real electrician


So this relay energizes the "outlet" to the machine when the converter is on, and disconnects the "outlet" when the converter is off. I understand that a plug outlet is not needed as the machines can be hardwired together.

Phil

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Posted · Report post

Thank you all for your help. Here is the diagram of how this is hooked up. The single phase goes to the motor starter of the load at all times. Is this as simple as moving the switch from its current location to the single phase input lines before the autogen? Or is there a better way?

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Posted · Report post


Using a relay to engage the controls when the 3ph power is active is the correct way to do this. It is not to code to tap a single phase off the converter for your control voltages.

just an FYI from a real electrician



Steve is correct.
I made mention of the generated leg because of the fact that it doesn't split.
In no way was I suggesting to use it or tap off of it to run the controls of the converter.

Some machinery does have voltage sensitive electronics and you have to be aware of the potential
for voltage differences on the generated leg.

Zach

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Posted · Report post

Every converter I have seen had to be running before any power was available to the machine.

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Posted · Report post


Every converter I have seen had to be running before any power was available to the machine.

Not sure why they wanted it that way but I think it is time for improvement. :) Gives me a heart attack when the macine tries to start without the converter running. Does not happen often but it does happen :(
Rob

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Posted · Report post

Based on the drawing, the "Autogen" device, and the magnetic starter for the motor, are both "hot" from the power supply.

The only thing actually being switched, is the auxiliary 3 phase motor.


If that is actually the case, then you want to pick up your "control" circuit, off one of the switched legs, feeding the auxiliary motor.


.

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Posted · Report post

Steve Sells is absolutely correct, I too am an electrician. A relay is the most appropriate answer to your problem.

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Posted · Report post

Just put your switch on your input legs. This keeps the two phases that go to both the rpc and the load motor dead, so that if you switch on your machine there is no power to it at all. Kind of like just turning the thing off at the breaker.

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