Low hp DC motor starting

jminer99er

jminer99er

Member
Location
Sacramento, CA
Im adding a new ¾ hp DC motor at 24Vdc to a hydraulic unit. This will be remote operated via mometary push buttons.

My questions is DC rated contactor/motor starter options. The motor is 3/4hp 1800rpm, 4pole, 24Vdc. The nameplate says A.ARM 31.8. I was thinking like nema 2 contactor, but I'm not sure if it's DC rated and have options for 24Vdc coils. Im not fimilar with dc motor starting. What would be some starting installation options? 1000022119.jpg
 
Yes I understand that, does anyone know know of a dc contactor/starter that is rated for 31A @ 24V from a reputable mfg, or will I have to use this type of solenoid?1000022122.jpg
 
jminer99er said:
Yes I understand that, does anyone know know of a dc contactor/starter that is rated for 31A @ 24V from a reputable mfg, or will I have to use this type of solenoid?
Click to expand...

May not be exactly what you want but talk to your local supply houses. They should be able to answer your questions as they relate to their products.

Try Grainger.
 
ptonsparky said:

May not be exactly what you want but talk to your local supply houses. They should be able to answer your questions as they relate to their products.

Try Grainger.
Click to expand...
Line side is a/c. (Im familiar with nema rated contactors, but not sure if they're engineered for dc loads) Attached is what I'm finding for a dc contactor. It looks overkill for a ¾hp 24v motor?
 

Attachments

  • Screenshot_20250822_172347_Chrome.jpg
    Screenshot_20250822_172347_Chrome.jpg
    366.9 KB · Views: 5
jminer99er said:
Im adding a new ¾ hp DC motor at 24Vdc to a hydraulic unit. This will be remote operated via mometary push buttons. If I loose shore power I can use dc power for emergency to drive hydraulics.

My questions is DC rated contactor/motor starter options. The motor is 3/4hp 1800rpm, 4pole, 24Vdc. The nameplate says A.ARM 31.8. I was thinking like nema 2 contactor, but I'm not sure if it's DC rated and have options for 24Vdc coils. Im not fimilar with dc motor starting. What would be some starting installation options? View attachment 2579253
Click to expand...
IFIFY. Small detail that should have been included.

The only power I've ran on anything that floated were oars.

Please note 90.2(B)(1)
 
I just finished a similar application. I had to control a 48VDC hydraulic pump. I used a DC solid state relay, backed up by a mechanical DC-rated contactor. The mechanical contactor wasn't rated for routine switching of the inductive loads (the brushed motor) so I used the DC SSR as the normal switching element, with the mechanical contactor as part of the E-stop circuit. Per the SSR's data sheet, I placed flyback diodes across the SSR's output terminals as well as across the motor itself. Worked a treat, and no chewed up contacts.


SceneryDriver
 
jminer99er said:
Thanks SD, what dc ssr did you use and contactor? Do you have the part# or picture of the setup?
Click to expand...
SSR:
Crydom p/n: D2D40

Contactor:
TE Connectivity p/n: EV100AAANA

Flyback Diode Module:
Vishay p/n: VS-HFA140FA120
NOTE: (2) diodes in one package

My motor FLA was 19A @ 48VDC, so the solid-state relay stayed nice and cool. That said, the SSR needs a heatsink. In my case, I cut the enclosure's subpanel on our waterjet from 1/4" aluminum, which worked well as a heatsink for the SSR and the diode module.

Per Sensata/Crydom, the diodes are not optional, and you will damage the contactor and the SSR if they're not included.

I slightly misspoke in my previous post; place a reverse-biased diode across the mechanical contactor to keep from chewing up its contacts if it opens under load, and place the other reverse-biased diode across the motor's terminals to prevent any regen current from damaging the SSR.



SceneryDriver
 
You must log in or register to reply here.
Top