What capacitor to use for motor to stop the power supply from tripping every second

Thread Starter

StormShadow93

Joined Apr 15, 2022
2
Hi I have a motor of 24V and 180W power and when I add load to it runs but the power supply keep switching on and off so i think more power supply is required but i am already providing 10Amps and 24V so i thought I could use a capacitor. Am I right in my assumption? And if yes how do I calculate the capacitor value?
 

AlbertHall

Joined Jun 4, 2014
12,023
Welcome to AAC, @StormShadow93

The motor, at start up, likely draws a lot more current than the 180W would suggest and so trips the supply protection system.
You could use a supply capable of a greater current. You could measure the resistance of the motor and so calculate the maximum current required by the motor (24V/motor resistance).
If you don't need the motor to start up quickly you could possibly use a NTC surge limiter to limit the initial current drawn by the motor.
 

KeithWalker

Joined Jul 10, 2017
2,354
A capacitor will not help. If you are supplying 10A at 24V to your motor, that is 240W. If your motor is rated at 180W, you are overloading it and it will not last too long.What is your supply rated for?. The answer is that you probably need a a more powerful motor and power supply.
 

Thread Starter

StormShadow93

Joined Apr 15, 2022
2
Welcome to AAC, @StormShadow93

The motor, at start up, likely draws a lot more current than the 180W would suggest and so trips the supply protection system.
You could use a supply capable of a greater current. You could measure the resistance of the motor and so calculate the maximum current required by the motor (24V/motor resistance).
If you don't need the motor to start up quickly you could possibly use a NTC surge limiter to limit the initial current drawn by the motor.
What value of the NTC surge limiter should I use
 
Hi I have a motor of 24V and 180W power and when I add load to it runs but the power supply keep switching on and off so i think more power supply is required but i am already providing 10Amps and 24V so i thought I could use a capacitor. Am I right in my assumption? And if yes how do I calculate the capacitor value?
If you're running a DC motor, with 10 amps at 24 volts you should have enough power, yes, and a shunt cap isn't going to do anything for reducing the current draw on your supply. You could use a shunt cap as a DC filter, but the cap would set up more DC amperage than before and again, trip your circuit breaker. Also, 180watts/24 volts=less than 10 amps and if that's an accurate 10 amp draw then something's wrong with your motor. On the other hand if your using an AC motor, I've had the occasion to become acquainted with capacitor-run motors, and an added capacitor might very well solve your overloading-the-source problem. You'll need to do some impedance calculations/estimations for the best/sufficient Farad value capacitor to place in shunt with your motor, and one minor point needs to be made here, by me, and that would be: are you using an induction motor (or in other words a Tesla Motor)? If you are, the surge current at start-up can become a problem for you and likely prohibits the simple use of adding another shunt capacitor to the "already shunt" capacitor-start arrangement. But since you're using only about 10 amperes "source" current through your circuit breaker, I think you'll be alright. Also you'll use much less than your circuit breaker trip-current. All that you'll need to do is some impedance matching with your motor and the proper value of added capacitance. Both branches of the motor and added capacitor circuit should be more or less the same impedance. To do that you'll need to know the maximum wattage or horsepower of the motor and it's rated voltage and if it's a single phase motor. Because I don't know how to specifically apply this technique to anything other than a single phase motor, sorry. But at only 10 amperes, you're likely alright again. Okay, calculate the "rated" amperes of the motor, either by watts law and voltage your motor runs on, or specified label from the manufacturer. With rated amperes known, next divide the rated voltage of your motor by that rated amperes to obtain an impedance figure for a "running" motor. That figure is what you need to use for matching to an added capacitance. In other words the capacitor impedance should be as close as possible to the motor's impedance. And from the required impedance at 60hz. VAC, you can calc the required Farad value of capacitance to wire in shunt with your motor for minimum current draw through your circuit breaker and power source. Then if you need the equation for calculating the Farad value it's: F= 1/Hz./2/π/Z
 
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If you're running a DC motor, with 10 amps at 24 volts you should have enough power, yes, and a shunt cap isn't going to do anything for reducing the current draw on your supply. You could use a shunt cap as a DC filter, but the cap would set up more DC amperage than before and again, trip your circuit breaker. Also, 180watts/24 volts=less than 10 amps and if that's an accurate 10 amp draw then something's wrong with your motor. On the other hand if your using an AC motor, I've had the occasion to become acquainted with capacitor-run motors, and an added capacitor might very well solve your overloading-the-source problem. You'll need to do some impedance calculations/estimations for the best/sufficient Farad value capacitor to place in shunt with your motor, and one minor point needs to be made here, by me, and that would be: are you using an induction motor (or in other words a Tesla Motor)? If you are, the surge current at start-up can become a problem for you and likely prohibits the simple use of adding another shunt capacitor to the "already shunt" capacitor-start arrangement. But since you're using only about 10 amperes "source" current through your circuit breaker, I think you'll be alright. Also you'll use much less than your circuit breaker trip-current. All that you'll need to do is some impedance matching with your motor and the proper value of added capacitance. Both branches of the motor and added capacitor circuit should be more or less the same impedance. To do that you'll need to know the maximum wattage or horsepower of the motor and it's rated voltage and if it's a single phase motor. Because I don't know how to specifically apply this technique to anything other than a single phase motor, sorry. But at only 10 amperes, you're likely alright again. Okay, calculate the "rated" amperes of the motor, either by watts law and voltage your motor runs on, or specified label from the manufacturer. With rated amperes known, next divide the rated voltage of your motor by that rated amperes to obtain an impedance figure for a "running" motor. That figure is what you need to use for matching to an added capacitance. In other words the capacitor impedance should be as close as possible to the motor's impedance. And from the required impedance at 60hz. VAC, you can calc the required Farad value of capacitance to wire in shunt with your motor for minimum current draw through your circuit breaker and power source. Then if you need the equation for calculating the Farad value it's: F= 1/Hz./2/π/Z
Stormtracker: As a second thought, if you're using a DC motor, there is a charging/discharging of individual electromagnets comprising the armature and field magnets in a DC motor, but to reduce current through a DC motor with a capacitor, the capacitor needs to be operating as an AC element. My best advice is to either consider that specific motor defective or buy a larger amperage supply. Or one of other method to re-route the inductive kickback of the armature and field magnet arrangement. And I've never done that, but it's quite easy. You need about 5 to 10 diodes with a current rating total of over the amperage you'd estimate your motor uses; and wire them to oppose current flow though to hem from the power source (in other wards the supply). Your motor may or may not drop it's kickback current though itself while at the same time oppose the supply voltage, this limiting current draw by your motor. Maybe, but? Also, how many volts does your supply put out? You might be trying to run a 24 volts motor on a 120 volt supply, in which case get yourself a 24 volts supply with an appropriate AC/DC output.
 
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MrSalts

Joined Apr 2, 2020
1,762
Let's say your motor is drawing 10A normally and 10 A more to start under load. Assume the motor take a half-second to get up to speed and you want the suplly to stay above 90% voltage supply (21V).

You would need a capacitor bank between 1 and 2 Farads. That much capacitance would likely pop your power supply before it gets fully charged - without even connecting the motor. Easiest to get a power supply with more heft.
 
Welcome to AAC, @StormShadow93

The motor, at start up, likely draws a lot more current than the 180W would suggest and so trips the supply protection system.
You could use a supply capable of a greater current. You could measure the resistance of the motor and so calculate the maximum current required by the motor (24V/motor resistance).
If you don't need the motor to start up quickly you could possibly use a NTC surge limiter to limit the initial current drawn by the motor.
This is the better reply on my page. Recommend follow this advice.
 

shortbus

Joined Sep 30, 2009
9,375
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