Ac contactors are widely used in low-voltage circuits and are an industrial necessity that is safe to use, convenient to control, and has a large quantity and wide application. At present, there are over a hundred million large and medium-capacity AC contactors with a rated current of 63A or more commonly used in China. The active power consumed by their operating electromagnetic systems during the holding process ranges from 10W to 100W. The consumed reactive power ranges from tens to hundreds of hals. The distribution of the consumed active power is approximately as follows: 65% to 75% for the core, 25% to 30% for the short-circuit loop, and 3% to 5% for the coil. For a major country like China, which is in the midst of accelerated industrialization and urbanization, and where energy demand is becoming increasingly tight, saving power resources has become an urgent task.
If the corresponding power-saving technologies are adopted for the operating electromagnetic system of the above-mentioned AC contactor, and the operating electromagnetic system is changed from the originally designed AC holding to DC holding, the vast majority of the lost power in the core and short-circuit ring can be saved, thereby achieving a relatively high power-saving efficiency (generally, the active power-saving rate is over 90%). Not only that, through the transformation, noise can be reduced or eliminated, the temperature rise of the coil can be lowered, and the service life of the contactor can be prolonged.