How to start 1hp DC Motor
How to start 1hp DC Motor
(OP)
What is proper way to start 1hp 24V DC Motor? Permanent magnet type.
Can I just use contactor with sufficiently high current rating?
(like, 100A, this is what my boss wants)
Or do I need to rig resistive ladder and use multiple contactors?
(I see lot's of literature on that, mostly old)
Or do I need to use switching controller with Triacs?
My goal is pretty minimal: turn the Motor on and off. I am looking for compact economic solution that does not damage the motor.
If I would use Contactor, should I switch both lines (like AC motor) or can I switch positive line only and leave Ground line permanently connected (it probably will work either way but what is recommended practice?)
Can I just use contactor with sufficiently high current rating?
(like, 100A, this is what my boss wants)
Or do I need to rig resistive ladder and use multiple contactors?
(I see lot's of literature on that, mostly old)
Or do I need to use switching controller with Triacs?
My goal is pretty minimal: turn the Motor on and off. I am looking for compact economic solution that does not damage the motor.
If I would use Contactor, should I switch both lines (like AC motor) or can I switch positive line only and leave Ground line permanently connected (it probably will work either way but what is recommended practice?)





RE: How to start 1hp DC Motor
What is this motor driving?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: How to start 1hp DC Motor
It drives a pump.
The application is marine steering gear.
RE: How to start 1hp DC Motor
http://www.eng-tips.com/viewthread.cfm?qid=349050
Keeping things simple will help Cletus and Bubba out when it comes time for troubleshooting. Unless you need speed control or reversing, a simple (properly rated) contactor should suffice.
SceneryDriver
RE: How to start 1hp DC Motor
RE: How to start 1hp DC Motor
RE: How to start 1hp DC Motor
Will the motor start once and be kept in continuous operation the entire time the vessel is underway, or will it be starting and stopping cyclically? Huge difference on heating effects and dissipation!
If continuous run using a closed-centre hydraulic system, it might make sense to use a DC-to-DC convertor that not only soft-starts the pump/motor assembly but uses a strain sensor transducer to control the hydraulic pressure of the oil by modulating the speed of the motor as required, with a hydraulic bypass valve used to unload the pump completely at times of zero demand...
Marine steering gear: pump is almost certainly positive displacement so as to provide the high pressure needed for the appication. So...will the pump be unloaded during starts or will the motor be starting under load? Or is the plan to have an open-spool hydraulic system? [The latter would almost certainly start unloaded by its very nature.]
The choices made will determine the best design...
CR
RE: How to start 1hp DC Motor
This really makes good thinking reference for me.
To answer the questions:
the motor start once and be kept in continuous operation the entire time the vessel is underway.
The motor will start with minimal load - when the system is not engaged and hydraulic pump runs idle - dumps all oil back into the tank.
RE: How to start 1hp DC Motor
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: How to start 1hp DC Motor
Thank you, good advice! And I did ... an learned that starter solenoids are often intermittent duty and i need continuous one. Nothing is easy but this is right direction.
RE: How to start 1hp DC Motor
RE: How to start 1hp DC Motor
RE: How to start 1hp DC Motor
'...learned that starter solenoids are often intermittent duty...'
Since this would be an off-design use, a question to answer is 'Why is the starter solenoid rated intermittent duty only?' Is it because in its intended service its contacts are only rated to carry their rated current for a short period of time? Or is it that the solenoid itself is only intended to be energized for a short period of time and would overheat and burn out if continuously energized?
In the first case it might be possible to use a starter solenoid anyway.
In the second, the clugy [?] method of starting the pump with starting solenoid 'A', parallelling the SS with a continuous-duty DC contactor 'B', then dropping out the SS 'A' would seem a quick and dirty and fairly inexpensive way to go.
CR
RE: How to start 1hp DC Motor