Current resistor calculation?

[Fastest1]

I believe that I am supposed to wire my steppers in bipolar series for best performance on my Dyna 3000. The stepper is a Portescap P852. I am using the G540 ez's but my question is, do I measure the resistance in the whole stepper connected together or measure the coils independently?

[Fastest1]

Too easy to answer?

[Mariss Freimanis]

I don't understand your question. Can you rephrase it?

Mariss

[Fastest1]

Mariss
Thank you for the response. When I am measuring the resistance of the stepper to calculate for the current resistor. I can either hook up the stepper bipolar series leaving me 1 wire per coil with the center taps are wired together, correct? Or if I just measure each coil before wiring them bipolar series? I am using the G540EZ and I think that I set the pot to match the resistance seen on the steppers. No directions that I have seen so far.

[Crevice Reamer]

Originally Posted by Fastest1 Mariss Thank you for the response. When I am measuring the resistance of the stepper to calculate for the current resistor. I can either hook up the stepper bipolar series leaving me 1 wire per coil with the center taps are wired together, correct? Or if I just measure each coil before wiring them bipolar series? I am using the G540EZ and I think that I set the pot to match the resistance seen on the steppers. No directions that I have seen so far.

Hi Fast.

I think you may have misunderstood something.

The previous G540 used a soldered-in resistor and the formula of 1K resistance per Amp of current to the motor. So a 3.5A motor would need a 3.5K resistor.

The G540 EZ pots should probably be set to the K rating of the motor current, whether wired in Series or in Parallel. There should be test points to measure this.

So if your motor is 3A in parallel, the pot would be set to 3K. If your motor is 1.5A in series, then the Pot would be set to 1.5K.

EDIT: I just remembered that Mariss intended to use Voltmeter readings. EG 1V= 1A. So 3A would= 3V at test points. 1.5A would= 1.5V.


BTW, Bipolar Parallel is usually the way to go, for best performance.

CR.

[Mariss Freimanis]

Fastest1,

Are you thinking of putting a current limit resistor in series with the motor coils?

If yes, don't do that. Wire the motors directly to the G540.

Mariss

[Fastest1]

Originally Posted by Mariss Freimanis Fastest1, Are you thinking of putting a current limit resistor in series with the motor coils? If yes, don't do that. Wire the motors directly to the G540. Mariss

No I was trying to measure the resistance to set the pot on the G540EZ. Dont I need to know what my stepper measures? I dont have any documentation on my lathe and the stepper info I can find to me is vague (and I am novice at best on electronics). I thought I should verify it. This is what I do know, I have 3 steppers of which I have a little info on each but not all.
(Y) Portescap P532 3.6 deg, 205oz, voltage?
(Z) Portescap P852 1.8 deg, 160oz, 140w, voltage ?
(Rotary tool changer) Vexta 2 Phase PH266-E1.2, 1.2a, 6v, 5 ohm
I also was advised to wire the steppers in bipolar series (I believe due to their age), Crevicereamer mentioned bipolar parallel was the way to go. I do know that others have reused the steppers and 1 of them is wired bipolar series. Any advice is appreciated, I will read more in the meantime.

[Fastest1]

After rereading my post. I should have said current "set" resisitor not "limit".

[Crevice Reamer]

Portescap data sheets. You will have to decide which version you have:

P532
http://www.tridenteng.co.uk/media/pdf415be0e2ba73b.pdf

P852
http://www.tridenteng.co.uk/media/pdf415be66900e78.pdf

Some basic CNC info:

http://crevicereamer.com/Page_2.html

CR.

[Fastest1]

CR, Thanks for the link, I do have this information unfortunately the stepper P852 has absolutely no markings on it besides "1.8 deg". All dialog boxes that should have serial, model or any info on the stepper are blank. The other stepper P532 (258 0,.7 14) has 2 sets of specs it seems. 1 says 2.4A the other says 3A. The stepper info you sent doesnt go past (258 0,.7 ???) Cant I just test the resistance to set the current set pot?

[Crevice Reamer]

Join the brown/white wire to the orange wire. Measure the resistance between brown and orange/white wires to get the Series resistance. That will determine which motors you have, and which phase Amperage to use for either Serial or parallel.

Once you know the Amp rating, you simply have to measure across the G540EZ test points with a Voltmeter and adjust the pot to proper Voltage.

CR.

[Fastest1]

CR
I have 3 different steppers. All have different readings. Also there is a difference if I measure right at the stepper or if I measure at the end of the harness about where the G540 would be. Not a long run but 3-5 feet total all shielded cable.

X axis Portescap P532 (258 0,.7 14), measures 1.8 ohms connected as you suggested at the stepper, at the end of the harness it measures 2.1 ohms.

Z axis Portescap P852 1.8 deg, (no identification besides the P852) measures 2.2 at the harness, I didnt measure at the stepper.

Tool Changer Vexta PH266 E 1.2, measures 11.1 ohms at the harness.

Each steppers wires are color coded differently til the harness however I could only get those results when I put the meter on the brown and orange and connected the purple to gray. It would always double what ever reading I could get off of any 2 wires that were measurable. I hope that makes sense.