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Thread: Need help! Balance voltage rotary converter motor 7.5 hp

  1. #41
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Many thanks to you Jim.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    It's my pleasure to help where I can.

    Probably reduce the capacitance on the T1-T3 and see if the voltage balances better.

    Maybe this will help you figure out what your pump should do. http://www.ingersoll-rand.gr/downloads/t30.pdf

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Quote Originally Posted by Jim Dawson View Post
    It's my pleasure to help where I can.

    Probably reduce the capacitance on the T1-T3 and see if the voltage balances better.

    Maybe this will help you figure out what your pump should do. http://www.ingersoll-rand.gr/downloads/t30.pdf
    It is good to have someone like you. I tried to reduce the capacitance on the T1-T3 and I got better voltage balance but the motor had more difficulty to start with pressure in the tank. After few hours of test, I endup with capacitance setup that gives me volts balance of 233 233 250 (T1-T2 / T1-T3 / T2-T3) with load (100 to 170 psi) and 239 247 256 with no load (less than 20 psi). With or without capacitance between T1-T2 the amp doesn't change on T1 and it is about 15 amp between 100 to 170 psi and 10 amp at less than 20 psi. I got 8.5 amp for T3 at less than 20 psi and no reading over 100 psi. Maybe I did something wrong, I'll try again tomorrow (if I have the time). Thanks for the link about ingersoll T30, I found that link too but I wasn't able to calculate the CFM for a motor pulley of 5 1/4 for 6.5 HP. I just sent an email to ingersoll, I'd like to know... I can't wait to use my new toy in my next project... but I still need to complet everything.



  4. #44
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Some can help me to connect my magnetic switch? It is a 3 phase switch that I run on one phase (see pic). I put a wire from 4T2 to 5L3, a wire from 95 to A2, a wire from 1L1 to 3. a wire from 4 to 96 and A1 to ground. Then when I connect 1L1 and 3L2 on the house braker, it doesn't work.

    Need help! Balance voltage rotary converter motor 7.5 hp-img_2575-jpgNeed help! Balance voltage rotary converter motor 7.5 hp-img_2576-jpgNeed help! Balance voltage rotary converter motor 7.5 hp-img_2577-jpgNeed help! Balance voltage rotary converter motor 7.5 hp-img_2579-jpg

    Attached Thumbnails Attached Thumbnails Need help! Balance voltage rotary converter motor 7.5 hp-img_2575-jpg   Need help! Balance voltage rotary converter motor 7.5 hp-img_2576-jpg   Need help! Balance voltage rotary converter motor 7.5 hp-img_2577-jpg   Need help! Balance voltage rotary converter motor 7.5 hp-img_2579-jpg  



  5. #45
    Community Moderator Jim Dawson's Avatar
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    If you are trying to run that 10HP motor with that contactor, it won't work. Much too small. You need one rated at least 10 HP, that one is only 2 HP @ 240V single phase

    Second problem is that the coil voltage is 500V, it won't work on 240V.

    The control power has to connect to A1 and A2. L2 connects to 97 and L1 connects to A1. 96 should be connected to A2. This is for the overload relay, when it trips, it breaks the circuit to A2, thus de-energizing the contactor coil.

    You need a different contactor.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Thanks again Jim, it looks like I'll have to spend some money... I hope I'll find something cheap.



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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    I found a 3 phase contacter with the right coil voltage and I put everything in an aluminium box but I don't remember how to wire the starter relay switch and it is giving me a hard time. When I use the manuel switch everything is working good, but when I wire the starter relay and I put power I just trip the breaker. I think I used to put T3 on position 5 and T1 on 2 and T2 on 1. If I use my manual switch, I wire the starter capacitor between T3 and T1 and it works. Can you tell me how I have to wire the relay switch before I realy damanged the relay. Thanks for your help.
    Need help! Balance voltage rotary converter motor 7.5 hp-img_2079-jpg

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  8. #48
    Community Moderator Jim Dawson's Avatar
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    The relay should be wired to only switch the start capacitor out of the circuit after manufactured leg (L3?) is generating power.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Thanks again Jim. I just found out that when the compressor stop it takes a while before the relay reset. Under normal operation condition I don't think it will be a problem but when I test the system, I have to wait until I hear the click before I turn the power on. I think I didn't have the time delay before... maybe I broke the stater relay...



  10. #50
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Happy to hear you're making progress. It sounds like it takes a bit for the capacitor to discharge and release the relay.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    This project is killing me... when there is no load, it works with the starter relay. At small load it works. But with more load it does't work. The starter relay kick off too soon, the motor is not at its real speed and the breaker trips. When I use the manual swich, instead of the starter relay it works.



  12. #52
    Community Moderator Jim Dawson's Avatar
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Maybe you need to use a time delay relay rather than the potential relay. That way you could set the time to whatever works, and have full control over it.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    You are right. Or maybe I'll use this 10 hp 230/460 as a rotary converter and get a 7.5 hp 230/460.



  14. #54
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    That will work too

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Since May 2018, I’ve been using a 10 HP 3 phase that I run on single phase. It works but the breaker trips once in a while.
    I just got a 5 Hp 230/460 and I ran my 10 HP 3 phase as a rotary convertor but when I tried to run my air compressor T30 (18.5 inch pulley on the T30) with this 5 Hp 3 phase with a 6.5 inch pulley the breaker opened. The 5 Hp ran and it was going faster and faster but it never reached full speed. The pulley on the 10 Hp is a 4.5 inch.

    Tomorrow I’ll review the voltage and amp balance of the system. Any advice?
    Need help! Balance voltage rotary converter motor 7.5 hp-5-hp-jpgNeed help! Balance voltage rotary converter motor 7.5 hp-10-hp-jpg

    Attached Thumbnails Attached Thumbnails Need help! Balance voltage rotary converter motor 7.5 hp-5-hp-jpg   Need help! Balance voltage rotary converter motor 7.5 hp-10-hp-jpg  


  16. #56
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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    What are the specs on the T30 pump? It could be that you don't have enough horsepower with the 5HP motor. A 5HP motor is only good for about 18 CFM at 90 PSI. Maybe try the 4.5 inch pulley, I think that's what I'm using on mine. Could also be a serious voltage imbalance.

    I just run my 5 HP on a 10 HP single phase rated VFD, runs fine at full speed.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Quote Originally Posted by Jim Dawson View Post
    What are the specs on the T30 pump? It could be that you don't have enough horsepower with the 5HP motor. A 5HP motor is only good for about 18 CFM at 90 PSI. Maybe try the 4.5 inch pulley, I think that's what I'm using on mine. Could also be a serious voltage imbalance.

    I just run my 5 HP on a 10 HP single phase rated VFD, runs fine at full speed.
    Hi Jim,
    I’m about to give up on the idea of running a rotary 10 hp convertor. I can’t find the pulley spec for my T30 2540. Maybe my 10 hp motor is not good enough for the project. I get better success when I add more capacitors between T1-T3, the 5 hp motor almost reached full speed before the 30 amps breaker trips. Maybe it is just the pulley but I can’t swap the pulley it is not the same shaft diameter.
    When I add more running capacitor between T1-T3 I just drift the voltage even more. Here are the voltages with the 10 hp no load with the 5 hp no load.
    T1-T2 = 258
    T1-T3 = 251
    T2-T3 = 240
    Here are the voltages with the 10 hp no load without the 5 hp.
    T1-T2 = 271
    T1-T3 = 275
    T2-T3 = 238
    Instead of adding more run capacitors between T1-T3, do you think I should try a starter capacitor between T1-T3 when the 5 hp starts? I also tried to run the air compressor with the 10 hp with more capacitors on T1-T3 and it looks like more voltage drift is better to start the motor with load on it. Do you think my starter capacitor is too small for my 10 hp? I used a 720-864 uf starter capacitor.



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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    I'm not able to find the specs on your pump, but what I could find kind of led me to believe that it's a 7.5 to 10 HP pump.

    I think you have 3 problems here

    1) the 5 HP motor is not large enough to run the pump with the pulleys that you are using.
    2) the 30 amp breaker is not large enough to run the system, should be a 40 or 50 amp with wiring sized to match.
    3) you have too much capacitance on the RPC, voltages are too far out of balance

    Increasing the starting capacitance of the RPC idler won't make any difference, assuming the idler motor starts properly now.

    I kind of get the impression that you are starting the RPC and the compressor at the same time, is this correct? If so, the proper sequence is to start the RPC, then start the compressor. The RCP start capacitors have nothing to do with running/starting the load, only for starting the RPC idler.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Hi, based upon my past experience, with a compressor, if you don't have the mains amps capacity to run a big compressor motor try using a larger or twin receiver tank(s).

    It will take longer to pump up a bigger tank but like going uphill in first gear you eventually get there.

    I used that method when I did a bit of sand blasting using a hobby compressor......the small compressor would pump continuously but at a much lower pressure once the trigger was pulled but with 2 tanks I was able to blast in short bursts while allowing the tanks to build up.

    The biggest problem with a domestic supply is that you are limited to the amps from the mains.

    Back in the 90's I ran a capstan lathe with a 3 Hp motor on a 10 amp mains supply and when I switched on it frequently tripped the breaker or at best dimmed the lights as the motor dug in.

    To cure the problem I fitted a 12 volt electric clutch from a car's air conditioner and let the motor run continuously......with capstans you are frequently stopping and starting.
    Ian.



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    Default Re: Need help! Balance voltage rotary converter motor 7.5 hp

    Quote Originally Posted by Jim Dawson View Post
    I'm not able to find the specs on your pump, but what I could find kind of led me to believe that it's a 7.5 to 10 HP pump.

    I think you have 3 problems here

    1) the 5 HP motor is not large enough to run the pump with the pulleys that you are using.
    2) the 30 amp breaker is not large enough to run the system, should be a 40 or 50 amp with wiring sized to match.
    3) you have too much capacitance on the RPC, voltages are too far out of balance

    Increasing the starting capacitance of the RPC idler won't make any difference, assuming the idler motor starts properly now.

    I kind of get the impression that you are starting the RPC and the compressor at the same time, is this correct? If so, the proper sequence is to start the RPC, then start the compressor. The RCP start capacitors have nothing to do with running/starting the load, only for starting the RPC idler.
    Hi Jim, I used the right sequence. But I now remember that I wasn't able to balance the voltage right in 2018 and I ended with a poor voltage balance to be able to start the 10 hp motor. Today, I decided to put back the 10 hp and I added 74 uf to the starter capacitor and I removed 10 uf to the T1-T3. The voltage balance is a bit better and the 10 hp motor has no problem to start and the breaker is ok.

    Before I start the 10 hp L1-L2 gives 243 volts

    After I start the 10 hp
    T-T3 = 230
    T1-T2 = 233
    T2-T3 = 252 volts

    I think you are right about the pulley on the 5 hp it is probably too big. The 10 hp as a smaller pulley and it gives more than 6 hp when it is run a single phase 220. I'll see if I can impove the voltage balance a bit more.



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Need help! Balance voltage rotary converter motor 7.5 hp

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