# Generate 2ph 60cy 115/115v

Discussion in 'General Electronics Discussion' started by colum, Aug 12, 2013.

1. ### colum

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4
Jul 25, 2013
I worked with 3 phase 220v and each leg to ground was 115v yet the total was 220v. I was told this depended how it was generated. I don't have access to 3ph any more and I want to run a small motor generator that calls for 2ph 115/115, 60cy in the motor and the output is 115v AC at 400cy
So what I need to do is generate 2phase 115v/115v 60cy from DC to run this contraption
I would appreciate any help to get this project finished and I've had it for 30 yrs and its probably military from WW2.

2. ### KrisBlueNZSadly passed away in 2015

8,393
1,271
Nov 28, 2011
You need a circuit called an inverter. It takes a DC input and generates single-phase AC at mains voltage.

Inverters typically run from 12VDC or 24VDC and can supply a few hundred watts. Large inverters can supply power in the kilowatt range.

There are two main types of inverters: pure sinewave inverters, and so-called "modified sine wave" inverters. The latter type produces a waveform that only a marketing person could describe as a "modified sine wave".

See https://en.wikipedia.org/wiki/Power_inverter

Edit: Wrong! Two-phase power really does (or did) exist. The phases are 90 degrees out from each other. See Wikipedia.

Last edited: Aug 12, 2013
3. ### duke37

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771
Jan 9, 2011
You will need two 60Hz inverters driven from a single frequency source and out of phase. This could be done with a higher frequency divided down or an analogue oscillator.

Do you have the aircraft to go with it?

4. ### woodchips

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0
Feb 8, 2013
Why not just use a single phase to three phase motor inverter?

Military 400Hz three phase supplies seem to run with one phase grounded, at least in the UK. this might be why it appears to only use two phases.

If it is 115V three phase then it will be 208V line to line.

Be careful, both the 115V and 208V line to lie voltages exist, obviously not compatible without a transformer.

5. ### colum

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Jul 25, 2013
Keep in mind that I need 2 inverters that need to have their phases offset exactly enough and that is the problem ..colum

6. ### colum

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Jul 25, 2013
Not sure how that would knock one phase out 90deg but I have a plan to hook up 2 small AC generators on a double shafted DC motor and manually offset one shaft
(and then go out and buy a WW2 plane HA HA thank you for the laugh) and then bring the results up to 115v/115v..I do love experiments..Thanks...colum

7. ### colum

155
4
Jul 25, 2013
Thanks for the advice but the only info I have is 2ph 115/115v and it could be 3ph because there is a third wire that is grounded to the motor..I may be working on this for another 30 yrs..colum

8. ### duke37

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771
Jan 9, 2011
You will need to find out whether it is two phase or three phase with one phase earthed. The motor will have four poles for 2 Phase and three poles for three phase. Can you see inside?

I attach circuits for producing two phase and three phase signals using CMOS.

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9. ### colum

155
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Jul 25, 2013
Thanks duke37 that is great information and I already have those ICs..There are 3 wires equally thick coming out and the same color and one is grounded to the side of the motor..I will try to look inside to see how many poles, once again thanks for your help...colum