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 »
Most labour-saving household appliances contain an electric motor of some description. They are the workhorse of these appliances and most of them are capable of coping with the work loads inflicted upon them. However, some motors, either through poor design or as a result of manufacturers’ cost limitations, are inadequate for the job they are required to do. Adequate or not, at some point it is almost inevitable that they will fail or simply wear out. To delay this, use the appliance with some care and attention, be aware of its limitations and carry out regular inspection and servicing. This will prevent small problems escalating into major ones
Not only do the sizes of motors vary greatly between products, so too do the ways in which they work. To diagnose faults successfully and service or repair appliances, a working knowledge of motors is essential. The following provide a basic introduction to the various types, a description of how they work, the appliances in which each may be found and their particular advantages and drawbacks. Specific problems can be found on individual appliances. Read the rest of this entry »
