Why do you think that a heavy duty switch is not a contactor?
How did you come to this opinion?
What do you understand about a switch, contactor and basic circuit theory?
I should warn you, I and many others here don't like playing twenty questions with somebody that doesn't respond. I realize that you may not have quick and easy internet access and that you may not be fluent in English. You will get much more useful information by responding to our questions asked of you than for you to correct people trying to guess what you are asking.
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"Don't disturb my circles." translation of Archimedes last words