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“Making adjustments to the potentiometer’s on a Electronmen EM - 285 DC - Motor speed regulator”.

Andy 1066

Jan 31, 2018
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Has any one any experience with installing and operating a Electromen EM - 285 DC Motor speed regulator (12/24v 20A). which are made in Finland.

Having read through the leaflet that came with the unit, and wired it up. I find that there are three potentiometer’s located on the circuit board. That need to have adjustments made to them. For anyone who is very knowledgeable on electronic, the terminology that is used in the leaflet would be very understandable. But someone like me who is very much an amateur hobbies, leaves me a little baffled.

I did email the companies support team, who did reply, but again basically repeating what was printed on the leaflet, that was from there head office in Finland.

The following was copied from the wiring, and installation sheet.

1. A range trim, to scale the usable speed range. (This is all that it says on the leaflet, it does not tell you how to go about doing this)

2. Current limit (l-lim ) limits the motor current, in other words the motor torque. This adjustment should be used to set the limit to suitable level according to the application?. (again it does not tell how to) I contacted there UK office, in there reply it stated that there are no specific guidelines on setting the current limit - they suggest experimenting, until you find something that suits the application in question. “Suits the application in question”, which is a little vague, so it seems its a case of hit and miss there.

3. Load compensation (RxI ) should be set to minimum in the beginning. Next set the motor rpm 20-30 %, and slowly increase compensation and simultaneously try loading the motor. If motor rpm is not affected by the loading the compensation adjustment is in optimum. But if motor starts to twitch or running turns nervous, the adjustment is overcompensating. (This has a lot more information on how to accomplish this, it seems that you make the adjustment on the compensation potentiometer, when the motor is running, and then make the motor have to do some work, and the reaction from the motor, dictates the adjustment’s that need to be made). Thats if I am correct in my understanding of what I am reading?

So if anyone with experience of having to make adjustment’s, like the one’s I have to make, can give me the benefit of there experience, on how they went about it, and put it in more understandable term’s for someone with a basic knowledge of electronic’s I would be very grateful.
 

kellys_eye

Jun 25, 2010
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1. The small graph shown on the datasheet shows the limit setting. For example, at 50% setting (of the trimpot) the main control will output a voltage between 2.5 and 18V (approx).
2. This would be set for the 'stall current' of your motor*. Only you can tell us that.
3. Your understanding is correct. Set the RPM, load the motor to 20-30% then adjust the pot so there's no 'twitching'.

* or some current level that protects the motor from overload.
 

Andy 1066

Jan 31, 2018
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Thank you for your reply to my thread, I much appreciate you taking the time to post a reply.

Your comments on number one with the information regarding the graph on there data sheet. Where you gave an example, I very much appreciate, as I find it so much easier to understand something, when there is an example given. It will now allowed me to be able to set that potentiometer to the right setting.

Your comments on number two, have left me slightly baffled, as I said in my thread, I am very much an amateur hobbies.

To quote from your reply “This would be set for the stall current of your motor (or some current level that protects the motor from overload) only you can tell us that.”

The electric motor in question is a 24V DC 200watt 3200r/min 13A.

When you say stall current of your motor How does one ascertain the stall current of an electric motor?

Would I be right in saying that The Current Limit needs to be set for the amount of current that the electric motor will need to do the work required? by doing this, the electric motor does not struggle to do the work, so that it does not heats up, and then blow the fuse protecting the motor.
 

kellys_eye

Jun 25, 2010
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Would I be right in saying that The Current Limit needs to be set for the amount of current that the electric motor will need to do the work required? by doing this, the electric motor does not struggle to do the work, so that it does not heats up, and then blow the fuse protecting the motor.
That's one way of doing it but your motor rating (200W @24V = 8A) suggests simply setting the limit to 8A would suffice. If you can get a 3 ohm resistor (rated at 10W minimum - but you'll have to be quick about setting the trip level as you properly need a 200W device!) you can adjust the trip accordingly.

Probably safer to apply your working load, add a little extra (some manually applied additional friction will do) and set at that level i.e. slightly ABOVE the actual working load.
 

Andy 1066

Jan 31, 2018
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Thank you for your reply, containing your suggestions on how to set the Current limit.
 

Delta Prime

Jul 29, 2020
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This is carryover.
Why didn't you just say you're application! you want to spin a shaft of an alternator at 3000 RPM in order to produce 230 AC. Is there anything else you'd like to share?

 
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