Why does a contactor hum

Contactors need to be protected from condensation in order to keep the pole surfaces of the magnet free from corrosion. The reason for this is that higher voltages will increase the speed of the electromagnet at closing. Lower voltages will decrease the speed at closing. Both these factors can lead to a higher level of contact bounce at closing. High voltage and the increased speed at closing also contribute to some increased sound.

The air gap is the distance between the pole faces of the yoke and armature which is at a maximum distance when the device is open or OFF. The amount of current required to pick-up and seal an AC or DC controlled device can be calculated from the VA ratings for inrush and seal found in the specifications for that device.

Simply divide the VA rating by the coil voltage to calculate the required ampere rating of the control source. Debris, especially large debris like plastic or metal shavings may make the device noisy and may cause the coil to draw more current than it is rated for at seal.

Oxidation and rust can appear on pole faces and cause noise, also. Voltage from the thermostat is sent to the contactor and is registered by the contactor's side terminals. How does a contactor work? A contactor is an electrically-controlled switch used for switching an electrical power circuit. A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a volt coil electromagnet controlling a volt motor switch.

Do relays make noise? Clicking noise in your car's fuse box is caused by a relay that is turning on and off rapidly. This can be caused by a computer failure, resistance in the ground wire for the control side of the relay or high resistance in the power supply to the control side of the relay. How do you make a relay buzz? A small amount of voltage to a relay will make it buzz or hum and even chatter if enough is present.

Bob, Its possible you have some voltage on the relay that is causing it to buzz. A solenoid is a magnetic switch. Apply power and the magnet activates pulling on a plunger and activating the switch. Why is my starter relay buzzing? Low battery, corroded battery connections, or a bad battery cable. The buzzing is the starter relay trying to start the engine. As soon as it applies the load of the starter to the system, the voltage drops and it drops the starter relay out.

Why does my hid relay buzz? The reason the buzzing occurs even with the ECE's connected directly to the ballasts is that the relay is still receiving the pulse.

Putting the ECE's in the path of the pulse and having them receive the pulse before the relay may solve the issue.

What is a definite purpose?