How to Calculate

Rating of contractors is calculated based on their profile. History of the contractor, major projects completed, on going projects , financial situation, Organisation structure, certification as like ISO,BVQI etc are the main points to be used for reference.

Example:- L&T, Relaince, GMR

contractors???

I think you might want to try again.

Dear jvslnchari,

You have asked for help on Limit switch, 440V coil on 220V supply, DOL starter wiring diagram, compressor connection etc. You have got some good answers to all of them. Have they helped? Have you got what you wanted? Please go to those threads of yours and respond to the comments, thank you. Otherwise how will we know that you have understood what we wanted to say?

Now, this question - selection of CONTACTORs (please note the spelling) for MOTOR (ditto) control is a vast subject. You need to study this weblink, which is an online software tool for selection of contactors and other components for motor control.

http://www.abb.com/product/us/9aac100741.aspx#

Please study it and ask your questions again. Thank you.

Please refer to the Type 2 Co-ordination based Switchgear Selection Charts of leading Low Voltage Switchgear Manufacturers. If you are unable to get, kindle mail me thro this forum's mailbox so that I can send you my company's Type 2 Charts.

Great answer!

CR4 family are very helpful and effective in technical opinions. But be specific with your question/s. Review your questions with dictionary(not dick-show-nary) in your hand before posting.

Contractor- is far different from contactor, likewise MOTERS is not a motor.

Similarly Capister is different from capacitor or BARBAR Shop is not a BARBER shop.

First of all, ur spelling mistake has converted Contactor to Contractor (thats what i presume) both are separate issues. Contactor is used for Supply Input to the Equipments such as Motors, Fridge, AHUs etc whereas COntractor is a team who does Electrical Jobs.To decide Contractor obviously his experience is to be checked & to decide COntactor application or purpose is to be checked. Rating is decided based on Equipment rating (Current rating).

Contactor basically is a switch with Air break COntacts similar to Normal Switch but Contactor can be used to control Electrical as well Electronic Equipments based on rating as normal switch cannot be used for all applications.

Contactor ratings are not generally calculated. Instead, they are usually looked up in manufacturers' catalog data, and are selected to equal or exceed the the motor's current, voltage, and service requirements. In the IEC world, the service is designated as AC1, AC2, AC3, or AC4 (in increasing severity.) In the NEMA (U.S.A.) scheme, there are a few rough equivalents such as standard, jogging, and plugging duty. I forget just which matches up to which, but I leave this as is a research opportunity.

Did you mean to say "contactors"?