Capacitors used for motor starting may have metal or plastic outer casings with an insulated top with two terminals. Internally the two terminals are connected to two sheets of metal foil with an insulator between. This package of large surface area is rolled into a cylinder which fits into the shell of the capacitor. As the voltage supplied to one terminal is alternating (at 50 times per second), so does the polarity of its connected foil. An opposite movement of electrons is induced in the other foil, even though they are insulated electrically. This causes a delay in the electrical path, and this, in the case of an asynchronous induction motor, gives the outof-phase feed to the start winding. Read the rest of this entry »
Many household appliances have some means of governing the temperature at which they operate. Examples include the regulation of high temperature ovens and heaters by switching elements on or off and, at the other end of the scale, the control of low temperatures in refrigerators and freezers by turning the compressor motor on or off.
A thermostat is an automatic device for regulating temperature. They range in type from the simple single action switch, which turns off or on at one pre-set temperature, to the fully adjustable type, which can be adjusted within a given range. Read the rest of this entry »
In recent years, the microwave oven has become a very popular kitchen appliance. However, many misunderstandings about the safety aspects of cooking with microwaves have arisen. Perhaps an understanding of how this appliance works will dispel these fears and misconceptions.
Repair should always be carried out by a professional microwave engineer. The reasons for this are the danger of high voltages present within the appliance, the requirements of the intricate fail-safe doorinterlock system and the possibility of microwave leakage if parts are not correctly fitted or aligned according to manufacturer’s instructions. Read the rest of this entry »
