DC Motor Surge Current Protection

[gsameer444]

Hello All
I am using a DC motor(Linear DC Actuator) in Solar Tracking system. To drive and protect the AC induction motor, normally I am using VFD. Similarly to drive and protect DC motor, should I used external DC drive? Most of the motor companies are suggesting Solid state relay to protect the motor from overload voltage or current.
Cant we need, soft start and stop provision in DC motor since that is not possible with Solid state relay?

 

[7anoter4]

See-for instance:

http://www.cableform.com/himp/himp-dcsmss.htm

 

[Skogsgurra]

Linear actuators are usually low power things, seldom more than a kW. Often considerably less.

The simplest solution is to use a series incandescent lamp. Select one that is rated at about half the motor voltage and around half the motor LRA. That will be a good starting point and will give you a soft start with any relay, contactor or SSR. The non-linear characteristics of the lamp (low ohm at low voltage) will give you good starting torque and the increasing resistance will protect the motor if overloaded (hitting a positive stop). If the armature is a low resistance one, you will need to increase lamp voltage to prevent lamp from burning out.

See

http://electronicdesign.com/components/lamp-eliminates-need-limit-switches-flap-motor-control

Gunnar Englund

http://www.gke.org

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