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sujinvipin
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Join Date: Aug 2011
Posts: 93

Duty Cycle

01/02/2012 4:14 AM

Why does the current rating increases when duty cycle decreases in a contactor or for any duty dependent machines?
eg: current rating for a 100% duty cycle is 123A but for 75% is 150A. Why is this?
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Tornado
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Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
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#1

Re: duty cycle

01/02/2012 4:22 AM

During the 25% off time, the contactor that was carrying 150A can cool down.
If carrying only 123A, it doesn't get so hot as to need a cool-down period.

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kvsridhar
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Location: Temporarily at Ashburn, VA
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#2

Re: duty cycle

01/02/2012 4:26 AM

i sincerely hope you are not serious. In case you really are....

At 100%, the contactor is ON continuously. At 75% duty, it is ON for ¾ of the specified period of time, and then gets ¼ of the time as a cooling period. So, it can withstand more current through it.

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rakesh_semwal
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Location: India, 200 Km. North of Delhi.
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#3

Re: Duty Cycle

01/02/2012 10:29 AM

let us assume a Donkey can go 50KM with one meal with a load of 50Kg, But if you load same Donkey with 25 KG it may go up to 70 or 75 KM, and if Donkey rest after every 25 KM it may Go 100Km with that one meal.
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sujinvipin
Commentator

Join Date: Aug 2011
Posts: 93
#4

Re: Duty Cycle

01/03/2012 2:39 AM

Thank you , i got my answer, lesser the duty ratio greater it can withstand the current , i just want to confirm it.
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