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Participant

Join Date: Dec 2008
Posts: 4

What is Duty Factor?

01/07/2009 11:15 PM

what is duty factor of the motor?

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Guru

Join Date: Sep 2006
Posts: 4513
#1

Re: duty factor

01/08/2009 12:41 AM

Motor? What motor? I don't see no motor!

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Guru

Join Date: Sep 2006
Posts: 4513
#2

Re: duty factor

01/08/2009 12:59 AM

The duty factor (or 'cycle') of a motor refers to the on-time of the motor versus the total time. If a motor operates for 4 minutes out of ten, then it is operating at a 40% duty factor. Mathematically, DF = 100% * on-time / (on-time + off-time).

Anonymous Poster
#3

Re: duty factor

01/09/2009 1:45 AM

thanx

Power-User

Join Date: Jan 2007
Location: South Africa Johannesburg
Posts: 187
#4

Re: What is Duty Factor?

01/09/2009 2:55 AM

Sometimes also called "duty cycle". In a nut shell, on time ratio to off time.

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Guru

Join Date: Dec 2007
Location: Mumbai, India
Posts: 1984
#5

Re: What is Duty Factor?

01/09/2009 6:15 AM

I would like to add. In certain applications motors are not required to run continuously such as water pumps, Hoists, cranes, etc. Hence motors are designed for periodic duty cycle which can be 40%,which means if the duty cycle is 10 minutes then motor can run for 4 minutes and rest for 6 minutes in duty cycle of 10 minutes.

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Power-User

Join Date: May 2008
Location: San Jose, CA, USA
Posts: 121
#6

Re: What is Duty Factor?

01/09/2009 12:44 PM

You are right that motors are designed to take care of the duty factor, expressed as % between load time and total running time. At the same time the motor sizing has to be done differently (for the same duty factor of 40%) if in the 60% "off time" the motor runs at no load (when the fan is cooling the motor, dissipating heat) as compared to the case the motor is shut off (does not turn) and subsequently the fan is also off so the heat dissipation occurs at a lower rate.

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Anonymous Poster #1
#7

Re: What is Duty Factor?

09/30/2011 1:37 AM

Duty cycle is a fixed repetitive load PATTERN over a given period of time.

Whereas, Duty Factor gives the total percentage of TIME for which the motor is switched ON.