PSU query Meanwell PSU 200w - 24v

Rodney1991

Joined Sep 11, 2022
5
Hey everyrone, i have a question regarding a PSU i have at home (once used for a 3d printer). Its a 200 watt PSU 230V AC 2-3A (i think) step down to 24V (8.8A).
I was hoping to jerry rig it to a 24v 12kW brushed DC electric oil pump (used for an emergency oil pressure system), i understand this is a very heavy duty pump hence why im here as the PSU will only pulse the motor. is there anything i can add to the circuit to assist in start-up.
PS: i ran the pump of an old 12V battery laying around and pumps fine (draws about 1.7A on the meter) in theory the PSU shuold run it, Anyone any input as to how to make this run, Cheers..

Irving

Joined Jan 30, 2016
3,980
A motor on startup looks like a short circuit so your PSU is going into current limit and voltage has dropped to near zero. You may be able to get it started using a speedcontroller as a soft start. Alternatively, use a battery on trickle charge to get it started and disconnect once running.

BTW you don't really mean 12kW motor do you?

MisterBill2

Joined Jan 23, 2018
18,978
A 24 volt DC motor running on 12 volts will take about a quarter of the power. As it draws 1.7 amps on 12 volts, 4 x 1.7=6.8 amps. But the starting current of a high-inertia motor/pump assembly will be more than that. So get a second 12 volt battery and when the pump needs to run connect the batteries and power supply and it should work well.
I wonder, though, about the motor being "12 KW", because at 12 volts that would be a motor current of 1000 amps, and at 24 volts would be 500 amps, which is still a whole lot of current.
A 1.2 kW motor would draw 50 amps at full load, which is a believable amount of current.
Was the motor/pump package originally part of a hydraulic power unit? Operating the landing gear in some aircraft?

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seanstevens

Joined Sep 22, 2009
256
As suggested above, have a look at MOSFET soft start circuit:

Soft start

Rodney1991

Joined Sep 11, 2022
5
A motor on startup looks like a short circuit so your PSU is going into current limit and voltage has dropped to near zero. You may be able to get it started using a speedcontroller as a soft start. Alternatively, use a battery on trickle charge to get it started and disconnect once running.

BTW you don't really mean 12kW motor do you?
yes 12KW its a doosy, thanks guys

Rodney1991

Joined Sep 11, 2022
5
A 24 volt DC motor running on 12 volts will take about a quarter of the power. As it draws 1.7 amps on 12 volts, 4 x 1.7=6.8 amps. But the starting current of a high-inertia motor/pump assembly will be more than that. So get a second 12 volt battery and when the pump needs to run connect the batteries and power supply and it should work well.
I wonder, though, about the motor being "12 KW", because at 12 volts that would be a motor current of 1000 amps, and at 24 volts would be 500 amps, which is still a whole lot of current.
A 1.2 kW motor would draw 50 amps at full load, which is a believable amount of current.
Was the motor/pump package originally part of a hydraulic power unit? Operating the landing gear in some aircraft?
if it comes to having a battery attached then i may use the pump along side the vehicle and just run it off the 12v battery, a littler slower but i guess the inital energy required is too much for the PSU. it is 12kW lol. its an emergency steering pump for a mining dumptruck -designed to give 5-8 secs of 200Bar oil pressure. thanks for your input guys

Joined Jul 18, 2013
28,767
Personally I would never use a SMPS for a motor.
Always linear variety.

nsaspook

Joined Aug 27, 2009
13,423
Personally I would never use a SMPS for a motor.
Always linear variety.
We use SMPS peak-current supplies rated for 2 or 4 Quadrant Magnet Power. The protection profile matches linear supplies without the stupid Hiccup Mode shutdown and over-current brick-wall behaviors that cause issues when driving large reactive loads.
https://www.edn.com/over-current-protection-in-power-supplies-converters/

https://www.power-supplies-australia.com.au/blog/mean-well-power-supply-hiccup-mode
Don't assume that because one model of power supply within a particular series has constant current limiting, all of the other models in the same series will also have constant current limiting.

For example, the 200 Watt MEAN WELL RSP-500-24 has constant current limiting, whereas its 240 Watt counterpart, the MEAN WELL RSP-200-24 has hiccup mode.

We strongly recommend that you read the data sheets carefully when selecting a power supply. Even some of those that are constant current limiting have a proviso - the output voltage has to be greater than 50% otherwise it reverts to hiccup mode. Both the MEAN WELL HRP-75 and HRP-100 have this characteristic.

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Joined Jul 18, 2013
28,767
For simple tasks as the OP's, I just use a linear transformer and a bridge rect.
No cap needed.

Rodney1991

Joined Sep 11, 2022
5
Personally I would never use a SMPS for a motor.
Always linear variety.
What is the difference may I ask?

Joined Jul 18, 2013
28,767
For motor control.
One, they are generally more rugged, They are much simpler construction, and less to go wrong

Rodney1991

Joined Sep 11, 2022
5
For motor control.
One, they are generally more rugged, They are much simpler construction, and less to go wrong
Would you have an example of such a power supply I've never heard of linear

Thanks

nsaspook

Joined Aug 27, 2009
13,423
For motor control.
One, they are generally more rugged, They are much simpler construction, and less to go wrong
and they are heavy so they make good boat anchors when they do die.

Joined Jul 18, 2013
28,767
Would you have an example of such a power supply I've never heard of linear

Thanks
Simple Mains transformer of the right (k)va. and a bridge rectifier.

MisterBill2

Joined Jan 23, 2018
18,978
NON-REGULATED power supplies for motors and solenoids work well, sometimes. But when the mechanical designer orders up a 25 amp 24 volt DC supply to power 5 solenoid valves that draw 2 amps each there does develop a problem.
That pump motor is going to need A SERIOUS power supply, (12 KW=12,000 W)/24V=500 as I see it, Given that Watts=V x A and so A=W/V.
Of course that would be full load power, no load will be much less.
Probably this motor will not need to run for extended time periods??

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Joined Jul 18, 2013
28,767
NON-REGULATED power supplies for motors and solenoids work well, sometimes. But when the mechanical designer orders up a 25 amp 24 volt DC supply to power 5 solenoid valves that draw 2 amps each there does develop a problem.
10amp load on a 25amp supply a problem?

MisterBill2

Joined Jan 23, 2018
18,978
TYPO!! It was really 50 solenoid valves at 2 amps each. The guy thought the valves were a good deal. 120 VAC would have saves us a bunch of grief, Who would have guessed that all 50 valves would need to stay open for hours and hours.