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  1. #16
    Join Date
    Sep 2008
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    Riddells Creek, Vic.
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    831

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    Quote Originally Posted by Alf Scotting View Post
    Phase changer 6
    Voltage is within Essential energies tolerances but they say maybe the cable dia. to the shed is a problem - long run and 10 mm. dia. cable ?
    Will be contacting phase changer people this week for comment, trouble is each want to blame the other so I am going around in circles here
    If the 6 in Phase Changer 6 is referring to horse power I think you will have trouble starting the 5.5hp motor under any load, they are not designed for this type of load.

  2. #17
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
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    2,651

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    IMO you need to check what the supply voltage is when you try to start the compressor.
    I’m sure the Phase Changer guys will want to know anyway for troubleshooting.

    I’d start by checking another power point in your shed while you start the compressor.

    Then check the input voltage at the phase changer unit when starting.

    Assuming the power gets to the shed via a main switchboard in the house, also check the voltage in the house - before and during the attempted start.

    That will give a much better picture of what is happening and where the likely issue lies.

    Steve

  3. #18
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

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    Quote Originally Posted by Techo1 View Post
    If the 6 in Phase Changer 6 is referring to horse power I think you will have trouble starting the 5.5hp motor under any load, they are not designed for this type of load.
    Yes they are actually. My phasechanger 8 can start a 10hp motor under load.

    I would say either the electrical line to the converter cannot deliver the required amperage, lowering the volts to a degree the converter shuts down and restarts. It the voltage has dropped then more amps are required for the same load. If the wire has too much resistance then the amps can not get there.

    Another possibility is the compressor unloader valve is not working. Or some of the capacitors on the converter are weak. They take a hell of a flogging and there are a few that do not have long lives. They are about $30 each. Hopefully the board is right as they are over $1000. I have blown two boards on mine as it is an older unit that had a weaker board. It has been upgraded to the heavy duty board now.
    Gold, the colour of choice for the discerning person.

  4. #19
    Join Date
    Aug 2010
    Location
    Toorloo Arm, VIC
    Age
    39
    Posts
    1,270

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    I found the below paragraph here: Installation - Maintenance - Service | Phase Change Converters
    4. Air Compressors:

    In most cases air compressors work fine on a Phase-Changer even though starting loads can be one of the worst possible. Provided there is enough energy available from the single phase supply line to cater for the very high start up currents often experienced, the application will work. However there certainly are instances where this is not the case and the compressor will fail to start typically on the second start. Generally the air tank is empty on initial start and the compressor starts ok, however the second start occurs when the tanks is still under high pressure which results in high compression and extremely high mechanical starting loads. Some compressor manufactures cater well for this and have relief valves to remove all head pressure for start up, but sometimes this is completely inadequate. When the relieve valve is part of the one-way valve feeding the tank, head pressure in the collection pipe is vented to atmosphere at shut down, however this pipe volume is usually very small and is repressurised within a few piston strokes on start up - often before the motor has got up to speed. To overcome this start-up issue, Phase Change Converters offer a head pressure bypass kit comrising a 1/2” solenoid, T fittings, and custom made 415V timer. Simply connect the timer supply cable to the L1 and L3 phases of the Phase Changer, and the valve will vent to atmosphere at shutdown and for the first 8 seconds of starting. This reduced starting issues enormously and allows larger 3 phase compressors to operate on second rate single phase supplies. Click here to go to our accessories page for more info.
    I gather it's basically your ball valve solution, but automated. Might be worth looking into?

    I was actually trying to see if I could find any information on what self-preservation modes the Phase Changer has. My theory was that it monitors incoming current on the 240V line, and shuts itself down at a certain limit. The drop in voltage means a rise in current to deliver the same power, and this may have been just enough to put it over the edge.

    Quick bash of the calculator says for a 4kw load on single phase, every 10 volts you drop increases current draw by 0.67A. That's disregarding power factor as I have no idea how efficient the phase changer is, but it also has some effect on this. Given Australian electricity is now specified to be 230V +10% -6%, one would have to think it was in excess of 253V when the neighbour complained, otherwise they surely would have given him the same answer they gave you ("It's in spec."). And if they adjusted it they likely shot for 230V even. If we assume it was 255V before, and is now 230V, that's 1.7A increase on the 4kw load when it's up and running at full load. Not so much of an issue, until you consider startup/inrush current can be anywhere in the range of 6-10 times the full load current, so if you assume the worst case 10 times, you're now pulling an extra 17A at startup - likely to be more like 20+ more amps by the time you account for power factor.

    The increased current will also result in increased voltage drop over your 10mm cable to the shed, but the magnitude of that increase highly depends on what a 'long run' is. A startup current of 180A on a 100m run of 10mm will result in a volt drop of 80V, 160A on the run would drop about 71V. Over a 25m run, 180A drops 20V, 160A drops about 18V.

    Whether that is tripping some form of current protection in the phase changer, or whether the lower voltage combined with the extra draw is simply causing enough voltage drop under startup load for the control board to drop out, or some other problem, who knows without some testing. A good sparky could probably figure it out given enough time and some poking around with a clamp meter measuring current on the line into the phase changer, and a voltmeter across the input terminals, but of course you'll pay for it, and pay again for the solution if there is one.

    Hopefully the above gives some insight into possibilities of 'why' you are now having a problem, although never disregard the possibilities of coincidence (something has or is failing, unrelated to but directly after the supply voltage change).

    With all that said, I really have to say that if the ball valve setup you've currently rigged up is working fine other than the inconvenience, Phase Changes automated solution mentioned in that first paragraph certainly seems like the fastest and easiest way out, and may also be the cheapest (assuming they still offer it).

    On a side note, I suspect your neighbour may be able to tell you exactly what the street voltage is and was, if you wanted to know.

  5. #20
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

    Default unusable compressor

    Quote Originally Posted by Jekyll and Hyde View Post
    I found the below paragraph here: Installation - Maintenance - Service | Phase Change Converters

    I gather it's basically your ball valve solution, but automated. Might be worth looking into?

    I was actually trying to see if I could find any information on what self-preservation modes the Phase Changer has. My theory was that it monitors incoming current on the 240V line, and shuts itself down at a certain limit. The drop in voltage means a rise in current to deliver the same power, and this may have been just enough to put it over the edge.

    Quick bash of the calculator says for a 4kw load on single phase, every 10 volts you drop increases current draw by 0.67A. That's disregarding power factor as I have no idea how efficient the phase changer is, but it also has some effect on this. Given Australian electricity is now specified to be 230V +10% -6%, one would have to think it was in excess of 253V when the neighbour complained, otherwise they surely would have given him the same answer they gave you ("It's in spec."). And if they adjusted it they likely shot for 230V even. If we assume it was 255V before, and is now 230V, that's 1.7A increase on the 4kw load when it's up and running at full load. Not so much of an issue, until you consider startup/inrush current can be anywhere in the range of 6-10 times the full load current, so if you assume the worst case 10 times, you're now pulling an extra 17A at startup - likely to be more like 20+ more amps by the time you account for power factor.

    The increased current will also result in increased voltage drop over your 10mm cable to the shed, but the magnitude of that increase highly depends on what a 'long run' is. A startup current of 180A on a 100m run of 10mm will result in a volt drop of 80V, 160A on the run would drop about 71V. Over a 25m run, 180A drops 20V, 160A drops about 18V.

    Whether that is tripping some form of current protection in the phase changer, or whether the lower voltage combined with the extra draw is simply causing enough voltage drop under startup load for the control board to drop out, or some other problem, who knows without some testing. A good sparky could probably figure it out given enough time and some poking around with a clamp meter measuring current on the line into the phase changer, and a voltmeter across the input terminals, but of course you'll pay for it, and pay again for the solution if there is one.

    Hopefully the above gives some insight into possibilities of 'why' you are now having a problem, although never disregard the possibilities of coincidence (something has or is failing, unrelated to but directly after the supply voltage change).

    With all that said, I really have to say that if the ball valve setup you've currently rigged up is working fine other than the inconvenience, Phase Changes automated solution mentioned in that first paragraph certainly seems like the fastest and easiest way out, and may also be the cheapest (assuming they still offer it).

    On a side note, I suspect your neighbour may be able to tell you exactly what the street voltage is and was, if you wanted to know.

    Thanks J&K most informative and closest to the truth - have contacted phase change convertors this AM and they want to sell me their soft start device and basically said they would give me a refund if it doesn't fix the problem - can't be fairer than that, but it looks like when starting the compressor I am right on the limit - Changing to 240V motor would cost me close to their price of $500 and with rewiring would cost more - looks like I will have to save my pennies and bite the bullet - will keep you updated

  6. #21
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    Quote Originally Posted by .RC. View Post
    Yes they are actually. My phasechanger 8 can start a 10hp motor under load.

    I would say either the electrical line to the converter cannot deliver the required amperage, lowering the volts to a degree the converter shuts down and restarts. It the voltage has dropped then more amps are required for the same load. If the wire has too much resistance then the amps can not get there.

    Another possibility is the compressor unloader valve is not working. Or some of the capacitors on the converter are weak. They take a hell of a flogging and there are a few that do not have long lives. They are about $30 each. Hopefully the board is right as they are over $1000. I have blown two boards on mine as it is an older unit that had a weaker board. It has been upgraded to the heavy duty board now.
    My phase Changer is a Light Horse 5 model (5HP) and is probably one of the very early ones. The specifications state that maximum heavy load start capacity is 3HP and I have found that it will not run the 5HP motor on my lathe at high speed (maximum load), at lower speeds it has no problem at all.

    To overcome the hard starting issue in high speed range I have fitted a 3 phase in, 3 phase out, VFD between the output of the phase changer and the Lathe motor and can now start in any speed without tripping the circuit breaker. The added advantage of the VFD is that the Lathe now has variable speed control.

  7. #22
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

    Default unusable compressor

    Quote Originally Posted by Techo1 View Post
    My phase Changer is a Light Horse 5 model (5HP) and is probably one of the very early ones. The specifications state that maximum heavy load start capacity is 3HP and I have found that it will not run the 5HP motor on my lathe at high speed (maximum load), at lower speeds it has no problem at all.

    To overcome the hard starting issue in high speed range I have fitted a 3 phase in, 3 phase out, VFD between the output of the phase changer and the Lathe motor and can now start in any speed without tripping the circuit breaker. The added advantage of the VFD is that the Lathe now has variable speed control.
    I am trying to spray my car this week and having to open/close those ball valves is a PITA and inconvenient, have spoken to Peerless compressors this AM and they are not much help except telling me when the compressor reaches full volume it should "blow off" which it does -phase change convertors will make me a "soft start" device for $460 plus delivery which it seems is my only option - do any of my MW friends have any experience with this device and can confirm it will overcome my problem?

  8. #23
    Join Date
    May 2020
    Location
    Willowbank QLD
    Posts
    517

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    If you want a cheap and easy solution that will allow you to use what you have, but decrease the CFM of the compressor, you can change the pulley size. By doing this the motor won't draw as much power to run the compressor, but the compressor won't pump the same CFM.

    Steve

  9. #24
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

    Default unusable compressor

    Quote Originally Posted by Alf Scotting View Post
    I am trying to spray my car this week and having to open/close those ball valves is a PITA and inconvenient, have spoken to Peerless compressors this AM and they are not much help except telling me when the compressor reaches full volume it should "blow off" which it does -phase change convertors will make me a "soft start" device for $460 plus delivery which it seems is my only option - do any of my MW friends have any experience with this device and can confirm it will overcome my problem?
    Had an 'industrial' electrician look at my problem this week after confirming motor was O.K.- in conversation with phase changer they decided my convertor was quite old and PHC have offered to update the software on my unit which 'may' overcome my problem - 50/50 chance - my neighbour has suggested I hire/purchase a 3ph. generator and I will look into the cost of this option
    will keep you posted when updated control board is fitted - thanks to all who have contributed

  10. #25
    Join Date
    Mar 2011
    Location
    Taree NSW
    Posts
    119

    Default unusable compressor

    Quote Originally Posted by Jekyll and Hyde View Post
    I found the below paragraph here: Installation - Maintenance - Service | Phase Change Converters

    I gather it's basically your ball valve solution, but automated. Might be worth looking into?

    I was actually trying to see if I could find any information on what self-preservation modes the Phase Changer has. My theory was that it monitors incoming current on the 240V line, and shuts itself down at a certain limit. The drop in voltage means a rise in current to deliver the same power, and this may have been just enough to put it over the edge.

    Quick bash of the calculator says for a 4kw load on single phase, every 10 volts you drop increases current draw by 0.67A. That's disregarding power factor as I have no idea how efficient the phase changer is, but it also has some effect on this. Given Australian electricity is now specified to be 230V +10% -6%, one would have to think it was in excess of 253V when the neighbour complained, otherwise they surely would have given him the same answer they gave you ("It's in spec."). And if they adjusted it they likely shot for 230V even. If we assume it was 255V before, and is now 230V, that's 1.7A increase on the 4kw load when it's up and running at full load. Not so much of an issue, until you consider startup/inrush current can be anywhere in the range of 6-10 times the full load current, so if you assume the worst case 10 times, you're now pulling an extra 17A at startup - likely to be more like 20+ more amps by the time you account for power factor.

    The increased current will also result in increased voltage drop over your 10mm cable to the shed, but the magnitude of that increase highly depends on what a 'long run' is. A startup current of 180A on a 100m run of 10mm will result in a volt drop of 80V, 160A on the run would drop about 71V. Over a 25m run, 180A drops 20V, 160A drops about 18V.

    Whether that is tripping some form of current protection in the phase changer, or whether the lower voltage combined with the extra draw is simply causing enough voltage drop under startup load for the control board to drop out, or some other problem, who knows without some testing. A good sparky could probably figure it out given enough time and some poking around with a clamp meter measuring current on the line into the phase changer, and a voltmeter across the input terminals, but of course you'll pay for it, and pay again for the solution if there is one.

    Hopefully the above gives some insight into possibilities of 'why' you are now having a problem, although never disregard the possibilities of coincidence (something has or is failing, unrelated to but directly after the supply voltage change).

    With all that said, I really have to say that if the ball valve setup you've currently rigged up is working fine other than the inconvenience, Phase Changes automated solution mentioned in that first paragraph certainly seems like the fastest and easiest way out, and may also be the cheapest (assuming they still offer it).

    On a side note, I suspect your neighbour may be able to tell you exactly what the street voltage is and was, if you wanted to know.
    For an update on this problem see MW forum ecogoo 1 ph to 3 ph 400V inverter

  11. #26
    Join Date
    Apr 2019
    Location
    Adelaide
    Posts
    589

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    So it can be assumed that the sparkle measured the voltage drop to the shed and the supply voltage to the rotary phase converter and that it all checked out ok?

    If you already have your home grown ball valve compressor load reduction system i fail to see why spending $500 to replace it with Phase Changers automated solution week make any difference to your problem (although it will be much more convenient).

    Have you actuality followed all the guidance and testing suggested above? Don't be a parts changer..... find the actual root cause.

    I feel your frustration. Good luck.

  12. #27
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

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    If the compressor's unloader valve is working, a cheap solution might be to add a small pressure tank connected to a tee in the line from the head to the main tank. The idea being to keep the line from the head to the main tank at low pressure while the motor spins up to speed. Maybe even a length of copper or steel pipe would do the job. Only downside I can see is a bit more noise when the unloader valve opens.

  13. #28
    Join Date
    Mar 2019
    Location
    Marulan NSW Australia
    Age
    72
    Posts
    4

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    Hello Alf, I have just been reading through this post. I think your problem is when the Supply Authority set your voltage back to something around 230v which is the Aust and NZ standard.
    I think you need to put a transformer connected to the input of your phase converter. A solution like this is done everyday in the US where they have many voltages to use. I live in the rural and my incoming voltage is usually 252v so if your supply was on the higher side and it was reduced to 230v. It's called buck or boosting using and autotransformer, it's really simple to do, lets say you wanted to increase the input voltage by 12v you get a 240v to 12v isolation transformer and reconnect it's terminals to make it an autotransformer then say you have 230v plus 12v well now you get 242v for your phase converter. This transformer does not have to be that big because it's only part of the full load.

    Jim

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