Heating contactor
A heating contactor is a contactor , i.e. an electromagnetically operated switch that is used in circuits in which the generation of heat by electricity is required.
Since a heater usually has no inductive or capacitive component in the power consumed, protection against overvoltages and overcurrents can be omitted. Because heating is not clocked every second, it can also be designed for a large number of switching cycles . In the case of controls where it is nevertheless necessary to apply a large number of switching cycles to the heater, the heating contactor serves as a galvanic isolating element to disconnect the consumer from the supply voltage in the event of a fault. The actual regulation then takes place with a wave packet control via a solid state relay .
Despite the use of power electronics , the use of this electromechanical component for galvanic isolation and with little switching consumption is standard. Since a heating resistor is characterized by a purely ohmic operation, the alternating current parameters such as starting current and phase shift are negligible, as they are practically nonexistent.
Examples of the use of heating contactors are night storage heating and component heating in the field of mechanical engineering . In the design of a heating contactor in contrast to a normal contactor, one recognizes differences in the load capacity, in the spark gaps and in the specified switching cycles.
Calculation example
- Night storage heating : 2 switching cycles (on / off) per day ⇒ ~ 700 switching cycles per year
Heating on a machine: one switching cycle per minute
This results in 525,600 switching cycles per year, whereby the cycle time in real switching is up to 2 seconds.