Building a Three Phase Mains Power System Simulator

RE: Building a Three Phase Mains Power System Simulator

phoenixcomm — Sat, 08 Oct 2022 00:12:26 GMT

Beautifully done!! 5 gold stars.

RE: Building a Three Phase Mains Power System Simulator

PeterFromSwe — Thu, 15 Sep 2022 09:40:04 GMT

This would be very interesting if extending the output signal to full mains level (3x230/400 Vrms). Application is demonstration of energy meters that consume max 2 W / 10 VA per phase. Would it be possible to extend this?

RE: Building a Three Phase Mains Power System Simulator

mcb1 — Tue, 12 Dec 2017 05:33:28 GMT

Here in NZ we have 230v phase to neutral (or earth).

In our three phase topology it is nominally 400v between phases.

Our power structure is such that they run three wires down the street.

A transformer is connected across this in a delta configuration, and the secondary is connected as wye.

This common point (neutral) is connected to ground, and for each house running from that transformer, they run a phase and neutral, which gives 230v.

If like me you have all three phase, then there are three phases plus the neutral.

The cable is usually a neutral screened cable and is designed to handle the current from a single phase, since a properly balanced load will have no neutral current flowing (very rare).

At worst it will continue the same current as a single phase.

This gives a very good reason why it is more efficient.

https://en.wikipedia.org/wiki/Three-phase_electric_power

Cheers

Mark

RE: Building a Three Phase Mains Power System Simulator

shabaz — Mon, 11 Dec 2017 13:04:53 GMT

Recently this video came up on Youtube recommendations:

https://www.youtube.com/watch?v=pW4HjuH1QRY

[View:/resized-image/__size/438x341/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4a903beb-596d-4ee3-857c-db42b5154f97/2350.contentimage_5F00_185872.jpg:438:341]

The video concerns a logic output and an inverted output (e.g. as done for driving piezo elements or bridge-tied-load audio amplifiers). Judging by the large amount of views, many people seem to be unsure how a higher AC voltage can be measured phase-to-phase (which is essentially what the two logic signals are in the video; they are 180 degrees out of phase).

With the 120 degrees out-of-phase, with this project it is possible to use any oscilloscope (or a multimeter set to AC) and observe the AC voltage (e.g. a peak-to-peak measurement or an RMS measurement) and see that the phase-to-phase output is higher than the phase-to-ground (or neutral) measurement.

The scope capture here shows the phase-to-ground measurement in white, and the phase-to-phase measurement in yellow. The yellow one is about 1.7 (i.e. square root of 3) times larger than the white trace.

[View:/resized-image/__size/620x372/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4a903beb-596d-4ee3-857c-db42b5154f97/7140.contentimage_5F00_185873.png:620:372]

It also explains why the lettering in this photo warns of 380V and not 220V (also proved in Excel above too, by Gene, for 120V AC).:

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4a903beb-596d-4ee3-857c-db42b5154f97/1373.contentimage_5F00_185874.jpg:620:465]

RE: Building a Three Phase Mains Power System Simulator

genebren — Sun, 10 Dec 2017 15:58:09 GMT

shabaz,

While not as cool as your hardware/software proof, your experiments got me thinking. I used Excel to repeat your experiment, and also saw that the sum of the three phase is zero. (the purple trace is the sum, highly zoomed in)

[View:/resized-image/__size/620x388/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4a903beb-596d-4ee3-857c-db42b5154f97/4760.contentimage_5F00_185869.jpg:620:388]

While I was at it, I looked into another mystery that I had always accepted as true, but never fully understood, having to do with 2-phase voltages. So I plotted the phase-to-phase voltages:

[View:/resized-image/__size/620x420/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4a903beb-596d-4ee3-857c-db42b5154f97/3364.contentimage_5F00_185870.jpg:620:420]

Looking at the data and doing a little math, I can now understand how 120V (single phase) becomes 208V (phase-to-phase). The peak of the phase-to-phase for the unity sine waves is ~1.732, this multiplied by the single phase voltage (120V) yields the answer, ~208V (phase to phase).

Thank you for making me interested enough in the puzzle to encourage me to take the time and do a little thinking.

Gene

RE: Building a Three Phase Mains Power System Simulator

shabaz — Sun, 10 Dec 2017 15:36:57 GMT

PCB layout now added, although this is not tested!

[View:/resized-image/__size/620x414/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4a903beb-596d-4ee3-857c-db42b5154f97/7485.contentimage_5F00_185868.png:620:414]

RE: Building a Three Phase Mains Power System Simulator

genebren — Sat, 09 Dec 2017 00:32:15 GMT

Hi Shabaz,

This is a very nice write up. I use to work on high energy three phase power inverters and I can clear say that I would prefer to work in the same voltage range that you are working with here,

Good job!

RE: Building a Three Phase Mains Power System Simulator

jw0752 — Fri, 08 Dec 2017 22:05:05 GMT

Hi Shabaz,

This is a very beneficial idea and a nice implementation. I can see such a device being very helpful in lab experiments involving 3 phase power. You have peaked my curiosity and now I want to know more about it.

John

RE: Building a Three Phase Mains Power System Simulator

fmilburn — Fri, 08 Dec 2017 21:44:05 GMT

Really nice write-up. I almost certainly will be putting something similar together to further my education.