The more typical unit of energy for ac power circuits is watt-hours, Wh. In this case, t is in hours. If P is in kilowatts, kW, and t is in hours, J has units of kilowatt-hours, kWh.

For the purely resistive circuit – for example, an incandescent light bulb – the power factor is 1 because the reactive power equals zero. Power factor can be an important aspect to consider in an AC ...

An AC circuit’s power factor is calculated using three aspects of its electrical power as they relate to one another (see the image associated with this article): * Real power—Power used to run ...

The losses in the power line, transformers, and cables are proportional to the square of the current. You can estimate this as follows. Assume the average load on the 55kW motor is 35kW. From Fig. 1, ...

Editor's Note: Here's another take on the transformerless AC line power supply, which finds use in some well-insulated, low-power devices. Our technical reviewer pointed out that C ac should be an ...