A continuous load requires an overcurrent protection device sized no smaller than 125 percent of the load. What is the maximum load permitted on a 100 amp overcurrent protection device? taken from workbook Basic Electricial Theory Series Volume 1 page 95 8.7 Reciprocals question # 12 how can this be answered using reciprocals?
Reciprocals
- Thread starter ketoe
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jtester
Senior Member
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If you write your first sentence as an equation, OCPD=........, and then solve that equation for load instead of OCPD, you'll see the reciprocal.
Jim T
Jim T
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- Lockport, IL
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- Semi-Retired Electrical Engineer
The word ?reciprocal? has seven definitions in the dictionary I keep by my desk. Only two relate to mathematics, and only one of those applies to the intended context. The reciprocal of a number is ?one divided by that number.? For example, the reciprocal of 2 is 1/2. So what would be the reciprocal of 1.25 (this being another way of expressing 125%)?
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Wouldn't the reciprocal relationship be 80%?
i.e. (16 amps)(125%)= 20 amps
(20 amps)(80%)=16 amps
i.e. (16 amps)(125%)= 20 amps
(20 amps)(80%)=16 amps
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Or in this case, a 100 amp OCPD is 125% of what number?
100 times (1/1.25) equals 80 amps.
Check the answer by taking 80 times 125%, and you are back to 100, so the answer was correct.
100 times (1/1.25) equals 80 amps.
Check the answer by taking 80 times 125%, and you are back to 100, so the answer was correct.
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