Major Classes of Appliances Single-Phase ac motors

The most common single-phase motor is the shaded-pole synchronous motor, which is most commonly used in devices requiring lower torque such as electric fans, microwave ovens and other small household appliances.

Another common single-phase AC motor is the induction motor, commonly used in major appliances such as washing machines and clothes dryers. These motors can generally provide greater starting torque by using a special startup winding in conjunction with a starting capacitor and a centrifugal switch. When starting, the capacitor and special winding are temporarily connected to the power source and provide starting torque. Once the motor reaches speed, the centrifugal switch disconnects the capacitor and startup winding.

Shaded-pole synchronous motor

Shaded-pole synchronous motors are a class of AC motor that uses single phase electric power to convert electric power to mechanical energy. They work by using a squirrel-cage rotor and a split stator that has copper shorting rings placed on it so as to shade a portion of the stator's magnetic field enough to provide starting torque.

The number of poles in an induction motor is an important factor in its interaction with non sine wave input. As a rule of thumb, motors with larger number of poles are more sensitive to harmonic distortion.

Incandescent Lamps

Early applications of lighting was using lamps which used a heated filament to provide light. The filament was made of tungsten and was placed inside a near vacuum glass enclosure. While it was cheap, it produced a lot of heat, so that it was inefficient too. Note that the incandescent bulb is a purely resistive load (power factor 1).

Inrush Current

The incandescent bulb is designed to operate at high temperatures. At normal operating temperatures, a tungsten filament has a resistance nearly 20 times its room-temperature resistance. So when a bulb is turned on, it draws a current nearly 20 times the normal current until it warms up. This current surge is called the inrush current, which lasts for 30-100 milliseconds. Again, something different from the "dumb load" point of view. Thus, 5 100 W bulbs in parallel, which would consume just 500 W in normal circumstances, will have a inrush load of more than 10000 W. More importantly, a huge current flows, and it is important that all components on the line can carry the current. For larger lamps, a small current flows to keep it at a reasonable temperature, called the "keep alive".

Evaporation

Another factor often overlooked in lamps is the resistance vs. time values. For an incandescent lamp, the power is proportional to the area. The tungsten slowly evaporates as the bulb ages, so that the power (and hence the light) produced by the lamp drops. Further, the light drops at about 5 times the rate of the power drop, so that the lamp becomes very inefficient with age.

After running for 75% of its rated life, an incandescent lamp must produce more than 93% of its initial light output in order to pass the standard test described in IEC Publication 60064.