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contactor for change over supply

contactor for change over supply

(OP)
hi
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

thanks

RE: contactor for change over supply

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

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

Product Line:
Products sold and used in the US

Environment:
Products sold and used in the United States

Cause:
Understanding how to select a device based on application and ratings

Resolution:
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.

Bill
--------------------
"Why not the best?"
Jimmy Carter

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