How we can choose OLR setting for an induction motor

You set the OL relay to the Full Load Current.

In practicle way first set OLR to FLR ,then run the motor with load .Now check the Ampere if too much diffrence between Ampere and OLR.Then reduce the setting to lower side.By this way the driven equipment will also be protected and also process cycle will be well in control

Check the rated current an the overload factor. Get the overload current and set the OLR according to that one, but lower

Good day, jayaprakash. Usually practice dictates that an O/L is set to the rated motor current. This does protect the motor sufficiently, however if one wants to protect mechanical or other equipment driven by this motor, one can further fine tune its settings as motors are often unnecessarily oversized for their applications. A mine electrician once gave me this rule of thumb for setting his process conveyor motors to protect his rollers etc. Run the motor, screw down the overload until the motor trips, then screw it up 20% and you have a very good motor and system protection. Hope this helps. regards

Hi guest,

Thank you for your's coments.By guessing from long time i was doing as you said.But now i am clear my doubt THANK YOU SO MUCH,and to all........

The motor should be selected based on two criterea; running power and short term overload capability.

This business of turning the OLR down to the running current of the motor is rubbish. All that will do is cause nuisance tripping and loss of revenue. Often times there are very short duration overload conditions that are well within the motor's capability to handle, but if you trip the OLR, you have now caused a shutdown and that unltimately means a loss of whatever that motor was doing and usually a cascading effect of other interdependent processes that ends up costing a LOT more money than you think you are saving by tripping early.

Do not 2nd guess the design engineer and cause yourself more trouble that you want. It saves NOTHING.