Air conditioning system of contactor

Air conditioning system of contactor

A vacuum contactor is defined as an electrical relay used to control the flow of power in a circuit. Lots of people also relate to them as a relay. A relay is actually defined as a device that responds to a small current or voltage change by activating switches or any other devices in an electric circuit. In the real world of heating and air conditioning, what this means is a vacuum contactor is capable of handling a higher current than a relay. Relays are often reserved for small pilot duty applications. The majority heating and air conditioning service technicians will not call a contactor a relay.

The working principle of vacuum contactor

Vacuum Contactors actually have at the very least two separate circuits in them. One circuit is the low voltage coil circuit and the other is the load circuit.The coil circuit in MOST home air conditioning or heat pump systems uses a twenty-four volt coil, nevertheless, there are a few systems that use a 230 volt coil in conjunction with a small relay that switches the contactor on and off. These 230 volt coil systems are principally on older systems or commercial units these days. Before changing any vacuum contactor make sure the correct coil voltage is used or a burnt coil may result. The coil voltage will be marked on a small tag on the side of the vacuum contactor. The line/load circuit in the home vacuum contactor is used to supply 230 volts to the load side of the equipment from the line side.

Large number of on and off cycles however, cause a couple of problems. The most obvious problem is that the contacts themselves get burnt from continually arching as they open and close the 230 volt connection. Contacts can actually weld themselves closed after some time. These a large number of cycles also cause the plastic sliding mechanism to wear. This wear usually causes the vacuum contactor contacts to stick closed although the thermostat has stopped sending an electrical signal to the coil. When this happens it often goes undetected by the homeowner and can rapidly lead to a frozen evaporator coil and or compressor. When a frozen condition exists the oil in the compressor is also freezing and can't lubricate the internal parts inside the compressor. This conditions amounts to the similar thing as running your vehicle with no oil! The other issue with burnt contacts is that there may be a voltage drop and added heat sent to the compressor and fan motor since the contacts are burnt.

vacuum contacto