Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


contactor for change over supply

contactor for change over supply

contactor for change over supply

if I have 2 supply power to a building.
one from the electric company and the other from generator for emergency ( loss power, fire for pump and etc)
the generator is located at building.
the contactor for the change over supply must be ac-3 or can be ac-1?

I have contactor that at ac-1 is take all the power but ac-3 is feet to les current


RE: contactor for change over supply

Quote (https://www.schneider-electric.ca/en/faqs/FA120833...)

What do the terms AC1 and AC3 mean?
What do the terms AC1 and AC3 mean?

Product Line:
Products sold and used in the US

Products sold and used in the United States

Understanding how to select a device based on application and ratings

AC-1 - This category applies to all AC loads where the power factor is more than 0.95. These are primarily non-inductive or slightly inductive loads, such as heating. Breaking the arc remains easy with minimal arcing and contact wear.

AC-3 - This category applies to squirrel cage motors with breaking during normal running of the motor.
On closing, the contactor makes the inrush current, which is about 5 to 7 times the rated full load current of the motor.
On opening, the contactor breaks the rated full load current of the motor.
Is your power factor above 95%?
You should be using a reversing contactor. It is dangerous to use transfer contactors without a mechanical interlock in addition to the electrical interlock.
Some manufacturers offer a mechanical interlock kit that may be field installed to provide mechanical interlocking between two contactors.

"Why not the best?"
Jimmy Carter

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close