Why does a contactor buzz

I tried just powering up one or the other contactor since I thought unlikely to get two bad ones. Both were new in box from reputable supply house. One box was even shrinkwrapped in that pallet wrap stuff. Cow said:. Click to expand You can call them at Good luck and happy turkey day! Mount them on some kind of rubber pad? Jraef Moderator Staff member. DP should really stand for D on't P urchase! No matter what brand you buy, DP is the cheapest junk made.

Technically, unless you are an OEM buying them for inclusion in an assembly that you will take to UL for listing, you cannot actually install them in the field if your system is going to be inspected. No but i did press down with the screwdriver it stops buzzing, ill try some tapping it and compressed air thats a good idea.

If that does not work ill bring them back to she shop and test them at V, since I find the V unusual. Well I brought out some spare contactors from the shop that I knew did not buzz swapped them in and they buzzed just as bad.

One of my old shop contactors actually smoked but it was really old 's era. I recehcked coil voltages with a true rms meter and still get V or slightly over which should be fine. Jraef said:. GoldDigger said:. If anything they are less likely to buzz when driven with a higher voltage.

And is well within the tolerance band for nominal V. The problem seems to be that for some reason the armature is not being pulled completely into the actuated position and the pole faces are buzzing as the 60Hz goes through zero current. There should be some feature, such as a pole shading coil, which is intended to keep the armature in position as the 60Hz current goes through zero, but that is a relatively weak holding force which will not work if there is any space between the parts.

If your "known good" contactors chartered too, I see only two strong possibilities: 1. There is something wrong with the AC waveform, not just the voltage, or 2.

There is something about the way the relays are mounted that is causing the problem. Twisting the frame, forming a magnetic short, etc. As we mentioned, these parts are relatively cheap and easy to replace. However, their failure can lead to expensive compressor or fan motor repairs.

What does a contactor do in an air conditioner? A contactor is an electrical relay that controls the flow of electricity to components in the AC unit. The contactor sends voltage to the condenser and outdoor fan motor. 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. Here are three common issues that could cause unexpected noises from an installed contactor. The intent is to confirm that the voltage ratings shown on the coil match the incoming voltage source to the coil.

Excess heat is the main cause of shortening the life of a coil. 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.