Hi, i am using a 24vdc power supply to power a motor. This motor will activate when an event occurs on a computer. I am wondering what the best relay to use would be. I found this
but im not sure if it will work correctly. Before i try working on the code i want to lay out my design. Would a relay or transistor be better to use?
What is your motor wattage/hp?
High power motors should not be used with tiny relays.
Noobian:
What is your motor wattage/hp?High power motors should not be used with tiny relays.
Honestly im not really sure what the wattage is the motor came from an aircraft. The motor runs on 24vdc and its does not move anything it just spins. I was able to power it with 2 or 3 9 volt batteries. Also it will spend 99% of the time off and will only run for a maximum of 1 minute. I don't believe it has a high wattage. Id rathe get it right i wouldnt have a problem with buying a relay that can handle a higher wattage.
If you can't use an amp meter to measure the running and stall current of the motor you can estimate stall current by measuring the winding resistance and applying Ohm's law. I = E/R. I - current, R = measured winding resistance and E = 24. You should always get a motor driver (mechanical or solid state relay, transistor, H-bridge, etc.) that will safely handle stall current as that is the most current the motor will ever draw.
md11pilot11:
Honestly im not really sure what the wattage is the motor came from an aircraft. The motor runs on 24vdc and its does not move anything it just spins. I was able to power it with 2 or 3 9 volt batteries. Also it will spend 99% of the time off and will only run for a maximum of 1 minute. I don't believe it has a high wattage. Id rathe get it right i wouldnt have a problem with buying a relay that can handle a higher wattage.
So it came from an RC aircraft? a brushless motor I presume. You can find out more if you know the model of that RC aircraft. Most RC aircraft motors are high power ones, except the ones used on tiny drones.
Does your motor look like this?
It's not the time that matters, its the inductive kickback problem which may occur if you use tiny relays. A 'solid state relay' is the best option in my opinion.
Noobian:
So it came from an RC aircraft? a brushless motor I presume. You can find out more if you know the model of that RC aircraft. Most RC aircraft motors are high power ones, except the ones used on tiny drones.
Does your motor look like this?It's not the time that matters, its the inductive kickback problem which may occur if you use tiny relays. A 'solid state relay' is the best option in my opinion.
Well the motor actually comes from a commercial aircraft it basically is a stick shaker that vibrates when the aircraft is entering a stall. do you have any suggestions on which solid state relay i should use?
Are the 9V batteries that you mention the small rectangular "transistor" batteries? If so the current is pretty low as those batteries can not supply much current. It would be best if you know the current requirement by measuring or estimating as explained above. Then there is no guessing.
Why an SSR? A logic level MOSFET ought to be enough.
But first you must find out the winding resistance / stall current - first steps first.
groundfungus:
Are the 9V batteries that you mention the small rectangular "transistor" batteries? If so the current is pretty low as those batteries can not supply much current. It would be best if you know the current requirement by measuring or estimating as explained above. Then there is no guessing.
Yes they were the rectangular ones but when i get home i will get the current requirement
md11pilot11:
Well the motor actually comes from a commercial aircraft it basically is a stick shaker that vibrates when the aircraft is entering a stall. do you have any suggestions on which solid state relay i should use?
Yes, a real aircraft.
It will likely require a few amps but may be less - I am not familiar with such things. SSRs are generally used for AC. groundfungus and MarkT have pointed out how to determine the stall current which is the critical specification as to what will be required to control it - measure the resistance with a multimeter and tell us what it is. Rotate the motor shaft very slowly as you do this to make sure you are getting the right measurement.
I cant rotate the motor as its a self contained unit as in this photo.
Well, give it a shake then to make sure the measurement is stable.
Why doesn't it have a proper nameplate on the assembly? Don't they do that any more?
Actually, if you could power it with 2 or 3, 9 volt smoke alarm batteries, it will probably be an amp or less.
Measure, record, use the battery to bump the motor a bit, measure, record. Do that a few times and use the lowest resistance measured in the calculation. You want to make sure the measurement is directly across a winding.
Paul__B:
Well, give it a shake then to make sure the measurement is stable.
Why doesn't it have a proper nameplate on the assembly? Don't they do that any more?
Actually, if you could power it with 2 or 3, 9 volt smoke alarm batteries, it will probably be an amp or less.
I just got word that from a similar motor the max current is 10A at 30VDC.
md11pilot11:
I just got word that from a similar motor the max current is 10A at 30VDC.
You might need a snubber.
Yes, a real aircraft.
I'm pretty sure my RC aircraft is real . I don't think I am imagining it .... ;D
Maybe its complex?
