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110 Volt relay Question

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goodpickles

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I need help with my 120 volt sugar cube relay. It says AC120V on the coil, when I hook 120 V ac to it , it makes a buzzing noise like the contacts are opening and closeing very fast. Does anyone have any suggestions? :?:
 

ivancho

New Member
What is controlling the relay?
Or are you just connecting it straight from the mains?

Are you sure it is rated for the load? is the relay a 120VAC? for sure?
 

UVRob

New Member
It sound like you have connected the 120 V signal directly to the controlling inductor. The inductor (inside the relay) will switch the relay on if it has a sufficient current through it, and off if it has no OR negative current through it. Your 120V AC will alternatingly send positive and negative currents through the inductor, and your relay will switch on and off with the same frequency as the AC voltage signal - probably about 50 times a second.

There are usually 5 terminals coming out of a relay switch. You have identified two of them, which correspond to the inductor, the inductor is physically seperate from the other 3 terminals. (Switching operation is a consequnce of the magnetic fields generated in the inductor.)

The 3 remaining terminals you should use to switch you appliance on and off. This is probably where 120 AC goes in series with your appliance.

The two terminals you have identified as the inductor should be connected to a DC supply. Sometimes a 12V DC supply - battery/mobile charger - is enough.

NOTE: Always use a 120V supply in series with a sufficiently high resistance!! :wink:
 

ivancho

New Member
I disagree with UVRob, AC relays are made so that the relay when energized "pulls" the contacts (in a normally open contact), and they stay pulled as long as the coil is energized....

A normal AC relay is rated to 10,000,000 operations more or less. if what UVRob says was true a Relay would only last less that 2 days :shock:

:arrow: Now, if you put a DC relay instead of an AC (given the DC relay tolerates the AC voltage) the contacts will open and close rapidly. That is why I asked if the relay coil was AC for sure.

Ivancho
 
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