DoAll Bandsaw 16-3 Transformer wiring

tonystoolroom · Jan 24, 2021

I'm repowering my DoAll 16-3 vertical bandsaw from three phase 220 >> Single phase 220.
I am trying to reuse the old Westinghouse motor starter/contactor. The contactor has a 110v coil.

In the head of the bandsaw there is a 3 phase 220 to Single phase 110 transformer. Since I'm not using L3 anymore, how do I need to rewire this transformer to get 110v?

The transformer has terminals for L1, L2, L3 220v and two terminals for 110v.

tonystoolroom · Jan 24, 2021

3 phase transformer pic

Strostkovy · Jan 24, 2021

Seems very weird to me that a single phase output transformer requires three phases in. Are you sure the input phases actually have magnet wire coming off of them and going to the transformer? I feel like there is just an extra terminal there to use the transformer as a terminal block.

tonystoolroom · Jan 24, 2021

Thinking about it more and it seemed weird to me too. I thought this was some odd transformer. After your comment I put an inspection mirror behind it and there wasn't anything connected to the center terminal. Then I put L1/L2 power to the outer terminals and pushed start the contactor closed and motor started. Mystery solved. THANK YOU !!

steve-l · Jan 25, 2021

What you discovered is common for DoAll. The only consuming device for 3 phase power is/are the motor(s). Everything else is powered phase to phase delta, effectively single phase. These single phase loads are the lamp(s), the control voltage transformer and the blade welder, if you have one. You will find that the motors are usually 12 wire units with two windings per pole. These can be wired in series for a 440/ 480V source or in parallel for a 208/220V source. (see the label inside the cover) In the case that the machine was sold for 440/480V use, there will be an additional step down transformer for the other 220V single phase loads. This info is not published in any manual I have ever seen.

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DoAll Bandsaw 16-3 Transformer wiring

tonystoolroom

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tonystoolroom

Cast Iron

Strostkovy

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tonystoolroom

Cast Iron

steve-l

Titanium

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