Variac hook-up?

[KB3RJH]

OK, kinda feels like a silly question but, here goes...

I have a panel mount 12amp (says max 15amps) variac that I am having trouble figuring out how to hook up. I have looked at a bunch of "How to hook up a panel mounted variac" sites and they keep talking about 5 terminals. The one I have only has terminals for 1,3 and 4. 2 and 5 holes are there but no terminals. Is there still a way to use this or do I have to be able to use the 2 and 5 terminals for this to work properly. If so, what should I use terminal-wise and where do the terminals connect to on the coil? The reason I am asking is because on one of the sites it was talking about using the 1 and 4 terminals for up to 170v or something to that effect. I just want to make sure I'm hooking this thing up correctly... 

73,

Anthony
KB3RJH

[W4EWH]

I have a panel mount 12amp (says max 15amps) variac that I am having trouble figuring out how to hook up. I have looked at a bunch of "How to hook up a panel mounted variac" sites and they keep talking about 5 terminals. The one I have only has terminals for 1,3 and 4.

Anthony,

Get an ohmmeter, and measure the resistances between all three terminals.

• Two of the terminals will have a fixed resistance that does not change when you turn the shaft. These will be connected to the AC line.
• Two terminals will show a variable resistance that can be reduced to almost zero. These two connecxt to the load.
• The remaining two terminals should show a variable resistance, but it will never go below the value measured in the first step. These two terminals are the "high" point for the primary and secondary, and they are never connected together.

HTH.

73, Bill W1AC

[W3NP]

You will be fine. Connect the "hot" ac input to term 1,  the neutral ac input to term 4 and the output to term 3. The output and input neutral share the same connection (term 4).

So: AC input to term 1 & 4 and AC output between term 3 & 4. You should put a fuse on the output of the wiper (term 3)

The extra terms 2 & 5 are/were for output voltage above the input voltage - like 140 vac or so.

[k4kyv]

Those extra terminals can be useful if your line voltage frequently drops below normal during heavy usage, for example, temperature extremes when the line may be loaded down with climate control devices.

[KB3RJH]

Thank you for the help, I understand now... Just wanted to be sure, don't need a new hairdo today... 

[W1RKW]

Put a fuse in line if you don't have one already.