In our electrical basic question is why we use relay to motor? and why can't an electrical engineer get job easy?

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Motor management relays are used for the protection of Motor from many factors/faults like, Thermal Overloads

Relay is used for switching the winding to get reliable start, e.g first it turn on the starting winding with running winding to the main supply after that it switched to the running winding.

and engineer can not get job easily now a days because number of engineers are increased now days.

Thank you for the invite, regret to inform that I would not be of any help to your question.

Thank You for the invitation ... I will agree with the answers that really covered your question ...Variety of correct info !

this relay is control high voltage in motor and  is operated by key lock switch the relay itself may have up to 24 contact points with in unit itself. this allows the control power for multiple machine to be locked out by the turn of single key switch.

second of your equation,the reality wants engineers  much experience. 

You can find the same trick at work in all kinds of machines and electrical appliances, where sensors are ready to switch things on or off in a fraction of a second using clever magnetic switches called relays.