Monday, June 6, 2011

Electrical Equations

Various kickspace manufacturers display their electrical power data in different forms. In order to convert between those forms, it is necessary to understand a few electrical basics.

There are many forms of electrical power whether it is horsepower (mechanical power), heat (thermal power) or some combination of the two such as candlepower (e.g. a light bulb which produces both heat and light).

Whatever the case, electrical power is measured in watts and is equal to volts x amperes.

The equation for this is: P = EI

P = power measured in watts
E = electromotive force measured in volts
I = current measured in amperes (amps)

Thus, if one manufacturer states that the motor draw on their kickspace is ½ amp and another says it’s 40 watts, the P = EI equation allows you to compare the two as long as they both are being run on a 115/120 VAC, single phase, 60 cycle power source.

Example: If manufacturer #1 says their kickspace is rate at 115/120 VAC 1/60 cycle and draws 40 watts, while manufacturer #2 says his kickspace is rated at 115/120 VAC/1/60 cycle and draws ½ amp. How does manufacturer #1 really compare to manufacturer #2?

Mfg. #1 P = E x I

Watts = volts x amps
40 watts = 120 volts x A

A = 40 watts
120 volts
A = 1/3 amps

We now see that manufacturer #1 has the advantage over manufacturer #2 since their motor draws fewer amps (current).

Going in the other direction, looking for manufacturer #2’s watts draw:

Manufacturer #2

P = E x I
Watts = volts x amps
Watts = 120 x ½
Watts = 60

Again, we confirm that manufacturer #1 has the advantage.