Speed controller, 24 volt DC, Electric motor,


I have a project I have been working on, that has me out of my depth with regard to my knowledge, as I am a very basic electronic hobbies.





It comprises of a 24V D.C electric motor, 200W, 3,000 rpm, 13A. which has a pulley, a belt from this attaches to a pulley on a drive shaft, where a flywheel is situated, and on the other end, is a pulley, with another belt, that goes to a pulley on a 230v AC alternator.


The motor is controlled by a Electromen EM-285 DC-Motor speed regulator 12 / 24V 20A. The regulator has three adjustable potentiometer, a Range trim, Current limit, and load compensation.


On the leaflet that came with the regulator for the installation, there is information that someone who works with electric motors, and speed controllers, which have potentiometer. Will know how to go about adjusting them to get the optima setting’s. But which has left me slightly baffled with my basic knowledge of electric motors, and electronics.





So I contacted the manufactures to see if they could help me, unfortunately they just repeated what was on the leaflet. But they did go off script a little, to quote from there email “There is no specific guidelines on setting the current-limit, I suggest experimenting until you find something that suits the application in question, start low and then increase”





So I experimented and found that if I sent the Range trim at a certain setting, and the current at another, the load compensation I left at zero.


With just the belt attached from the electric motor to the drive shaft, when I turned on the speed regulator, and increased the speed setting, the shaft started turning, I further increased the speed, and it picked up, and was moving very fast.


I then turn the speed down, and it only slowly lost speed, due to the motion of the flywheel. Until it was just turning over, and then I could slowly turn the speed up to a 100% again, and the flywheel would be whizzing around.





Next I attached the belt from the pulley on the drive shaft to the one on the alternator. Turned on the speed regulator, and slowly increased the speed, but this is when I found I had a problem, it would only rotate slowly. I put the speed controller up to 100% but it made know different to the speed.





The alternator shaft runs on two bearing, you can spin the pulley on it, with your hand, and it will do a couple of revolution before it stops, so there is know great resistants from the alternator spinning.


Also there is not a great difference in the force one has to use to spinning the flywheel by hand with just the electric motor being connected to the drive shaft. To when I then attach the belt from the pulley, to the alternator, and then spun it by hand.





But logic dictates, that I lost the speed, that I had before, (which I must point out was really fast). When I attached the other belt that goes to the Alternator.


So is the answer to the lost of speed, down to the adjustments of the Potentiometer, to be quite frank, Range trim, Current Limit, and especially Load compensation, I have a lack of knowledge and experience of working with.


I did go online to see if I could improve my knowledge, which I did to some extent.


So I did a little experiment, and increased the Current limit which certainly made a difference to the speed. As the test was progressing there was a smell of melting plastic. Looking at this fuse, that, protects the electric motor which is a spade type, that are used in motor car, the plastic casing was melting!, it was acutely bubbling! but the fuse had not blown, so I turn off the power. Let everything cool down, put a new fuse in, and did a quick test, and everything worked o.k, so nothing else was damaged.





Any thoughts, and suggestion on what the problem is, and how to go about fixing it, would be much appreciated.

 

Welcome to AAC.

Is the alternator connected to a load?
Please draw a diagram, it’s hard to follow a narrative. Include a schematic or wiring diagram.

 

The fuse rating matters. I've had manufacturers put in 30A fuses on something that runs at 2A. Is there any type of indication on the current limit knob to tell you what you're setting the current limit to? Or is it just a potentiometer. Sounds like you're going well over that 13a rating, if that module is capable of that.
Also from the sounds of it, thats whats going on. You're hitting the current limit, so the controller goes into constant current mode and will only output up to that current limit. It will decrease the voltage going to the motor to reduce the current that is going to it. And since its a dc motor, the drop in incoming voltage will reduce the speed.
If you have a clamp on ammeter that can read dc current, you can drop the current limit way down. Power up the motor with the load attached and measure the current and raise the current limit, but not above the motor rating. If you cant reach full speed before you reach your current limit, than it sounds like you need to reduce the load on the alternator, or you need to get a beefier motor.
and yes schematics/pictures/drawings always help in answering questions. Even if they're just crayon and a picture taken of the drawing still helps.

 

The fuse rating matters. I've had manufacturers put in 30A fuses on something that runs at 2A. Is there any type of indication on the current limit knob to tell you what you're setting the current limit to? Or is it just a potentiometer. Sounds like you're going well over that 13a rating, if that module is capable of that.
Also from the sounds of it, thats whats going on. You're hitting the current limit, so the controller goes into constant current mode and will only output up to that current limit. It will decrease the voltage going to the motor to reduce the current that is going to it. And since its a dc motor, the drop in incoming voltage will reduce the speed.
If you have a clamp on ammeter that can read dc current, you can drop the current limit way down. Power up the motor with the load attached and measure the current and raise the current limit, but not above the motor rating. If you cant reach full speed before you reach your current limit, than it sounds like you need to reduce the load on the alternator, or you need to get a beefier motor.
and yes schematics/pictures/drawings always help in answering questions. Even if they're just crayon and a picture taken of the drawing still helps.

The question remains: why does adding a free spinning alternator change the current draw so much. I am afraid that what is not being said is the alternator is wired to the motor. (see: motor to flywheel, flywheel to alternator…)

 

oooh like an over unity attempt? That would cause some issues. Yeah I'm working on the assumption that the electrical load is connected to the alternator and not free spinning. TS will illuminate us.

 

oooh like an over unity attempt? That would cause some issues. Yeah I'm working on the assumption that the electrical load is connected to the alternator and not free spinning. TS will illuminate us.

Yeah, except…

The alternator shaft runs on two bearing, you can spin the pulley on it, with your hand, and it will do a couple of revolution before it stops, so there is know great resistants from the alternator spinning.

 

Yeah, except…

Thank for taking the time to reply to my posting, sorry for the delay in replying, but it seems from the other reply to my last posting, that what I am trying to do is impossible. The following text is what I posting, if you have not seen it, I have also included the photos of my project.
The ideal behind my project came about because of the hike in energy prices, and fuel prices, we all felt here in the UK.
I had saw a video clip’s on U tube about flywheel’s, and wondered if it would be possible to use the force of a flywheel momentum, driven along by a low voltage, low wattage electric motor, connected to an alternator to produce my own electricity, to see whether it would be possible to cut my energy costs.
Of course the motor might struggle to turn the flywheel to start with, (which weighs 22.5 kg), but if I spun the flywheel first, and then turn on the motor, it would not be trying to turn a dead weight.

I based my thinking on this ideal, I had, around when riding a bike, when you are going down a gentle slop, if you carry on peddling, its really easy peddling, no great force of energy is required from you, so you burn less energy. So once the flywheel has some momentum behind it, the electric motor is under know great resistants when rotating.

The alternator I purchased is made in Italy, can be run by a petrol or diesel engine, (an expensive way to produce power now, because of the fuel prices) or you can buy a pulley kit, as I did. The Alternator its single phase brushless unit, 115/230 volts, 50 Hz 3000rpm, the output on this model is 8.5 kva. The sales person in the UK that I dealt with, who company import, and sell them, informed me that you need to get the alternator turning at 3100 rpm, to allow for the drop in speed of the alternator, when you start to draw power. I will mention here that the type of electricity that this type of alternator produces, will only power electric items that do not have any circuit boards within them.

I have attached some photographs of the test rig that I set up. I will mention here also, that one rotation of the large pulley, turns the smaller pulley on the alternator four and three quarter rotation, so this has allowed me to greatly reduce the rpm that the electric motor needs to spin at.

I had of hoped to post this thread earlier, but decided to to carry out a another test run, this time with the flywheel removed. Again the same problem, the maximum rpm I could reach was 290. So disconnected the belt from the pulleys, and ran the motor again, well the large pulley was really flying round, a lot faster than when the belt was attached. Another thing I noticed at the same time, was that I had a better control of the speed, when I increase and decreased the speed. than when I had the belt connected to the alternator, when there was a load

So it might be, which has been mention in a couple of replies, to my thread, that the power supply, which comes from a 300W AC-DC converter (which I have given the details about), might not be powerful enough to cope with turning the alternator, I have attached a photo of the power supply as well.

Any other thoughts and suggestion with the extra information I have given, would be much appreciated.

 

Two things:

1. The bad news is your enterprise was doomed before it began. The laws of thermodymanics make what you are hoping to do impossible, and though you could prove it mathematically, a simple logical proof should make it clear​

​

You can never get out more than you put it. This is because there is always a cost for running a machine—it comes down to friction in one form or another. In every attempt to take electrical power and do something “useful“, some of the power is inevitably going to be made into heat.​

​

Even if you could somehow create a literally friction free system, you would only, at its very best, break even.​

​

(Electric heating, with the goal of heating is the only case of 100% efficiency and it’s also proof that 100% efficiency is qualitatively indistinguishable from anything less than 100% and more than 0%).​

​

2. I suspect your problem with bogging down is simply not enough current from your supply under load. You can measure that easily enough. But it would be purely academic because you‘ll never get cheaper electricity by buying electricty and coverting it to… electricity.​

By the way, flywheels are used to store power. The resulting power will be more costly than the power purchased and stored, but, in principle, it could be cheaper to store power at low demand, low tarrif times for use during peak periods where costs are higher—in principle.

 

Two things:

1. The bad news is your enterprise was doomed before it began. The laws of thermodymanics make what you are hoping to do impossible, and though you could prove it mathematically, a simple logical proof should make it clear​

​

You can never get out more than you put it. This is because there is always a cost for running a machine—it comes down to friction in one form or another. In every attempt to take electrical power and do something “useful“, some of the power is inevitably going to be made into heat.​

​

Even if you could somehow create a literally friction free system, you would only, at its very best, break even.​

​

(Electric heating, with the goal of heating is the only case of 100% efficiency and it’s also proof that 100% efficiency is qualitatively indistinguishable from anything less than 100% and more than 0%).​

​

2. I suspect your problem with bogging down is simply not enough current from your supply under load. You can measure that easily enough. But it would be purely academic because you‘ll never get cheaper electricity by buying electricty and coverting it to… electricity.​

By the way, flywheels are used to store power. The resulting power will be more costly than the power purchased and stored, but, in principle, it could be cheaper to store power at low demand, low tarrif times for use during peak periods where costs are higher—in principle.

Thank you for taking the time to reply to my posting, with your conclusion that my project was doomed from the start, another one bits the dust.