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Thread: Soft starter on a wide belt sander?

  1. #1

    Soft starter on a wide belt sander?

    Do they make soft starters for 3 phase wide belt sanders? I saw a post on another site where some of the posters were saying that this might be possible. I have a 10hp Cantec wide belt and it pulls 100+ amps on startup giving me issues with my electrical setup. Once it runs for a few seconds the load decreases drastically. I know that a VFD will do this but a VFD for a 10hp wide belt sander is expensive. If I went the VFD route would it also require separate VFDs for the feed motor and table elevation motors? If so, we are talking $1,500 to $2,000+ in VFDs. I have a 25hp RPC but it cant handle the start up load my sander has. I am having 3 phase power ran to my shop soon so the RPC wont be needed but my shop has an old very large main panel that is already 3 phase it is just setup for single phase until they get the supply reworked. I can get 100amp breakers for $150 but anything over 100amps for this panel is $700+ with the necessary install kit for those large 6 space breakers. Long story short, I am just curious if anyone knows of a soft starter that would work here? Any links?

  2. #2
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    Check into VFD's or variable frequency drive. At work we use this on motors just for that purpose is to soft start, a vfd can be programed to ramp up to hz setting over that adjustable ramp time. I never heard of a VFD that is made just for soft start only, but I be dang they do. Again at work we just use vfd's on motors that work for purpose of soft start or to maintain static pressure. Here's some reading material for ya.
    https://realpars.com/vfd-vs-soft-starter/

  3. #3
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    Quote Originally Posted by Bobby Robbinett View Post
    Do they make soft starters for 3 phase wide belt sanders? I saw a post on another site where some of the posters were saying that this might be possible. I have a 10hp Cantec wide belt and it pulls 100+ amps on startup giving me issues with my electrical setup. Once it runs for a few seconds the load decreases drastically. I know that a VFD will do this but a VFD for a 10hp wide belt sander is expensive. If I went the VFD route would it also require separate VFDs for the feed motor and table elevation motors? If so, we are talking $1,500 to $2,000+ in VFDs. I have a 25hp RPC but it cant handle the start up load my sander has. I am having 3 phase power ran to my shop soon so the RPC wont be needed but my shop has an old very large main panel that is already 3 phase it is just setup for single phase until they get the supply reworked. I can get 100amp breakers for $150 but anything over 100amps for this panel is $700+ with the necessary install kit for those large 6 space breakers. Long story short, I am just curious if anyone knows of a soft starter that would work here? Any links?
    On my previous wide belt sander, a SCM Uno, it came with factory installed soft starter. From memory it is 7.5kw. On my new sander I fitted a VFD, only for the purpose to overcome the startup current because the main motor is a 18.5kw monster for my supply.

  4. #4
    Yes, it can be done. A Vfd would probably be cheaper than cobbling together a "soft start". That being said, you are probably going to have to rework the start/ stop and whatever interlocks you have. NOTHING can be between the Vfd and the motor.

    100 Amps isn't much on start up. What exactly is the problem? Have you checked the Capacitors in the Rotary? Wire heavy enough? No burnt contacts? What Circuit Breaker Panel do you have? I can probably find you a refurbished breaker.

  5. #5
    my 10 HP roto will start a heavy load 10 HP medium to heavy load machine. There were three levels when I bought it and I got middle level which had extra stuff and voltage regulation.

    The heavier model than what I bought I think was used for refrigeration and other heavy load applications. Dont get why your 25 HP roto cant start a 10 HP motor. always read you need 20 HP for 10 HP motor or something like that and that is not what I was told by the manufacturer I choose.

    Makes me wonder why machines cant or dont have a clutch system like a manual transmission car, you start the motor then ease it into running the sanding head.

  6. #6
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    What about turning on more three phase idlers; a big disk sander, lathe and DC fan before starting the sander? They can be switched off after the belt sander is up to speed. How many volt amps supply your RPC?
    Single phase 240 volt needs about 175 amps for 25 hp.
    Bill D.

  7. #7
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    What's the motor wiring look like? You might be able to use a wye-delta (star-delta) starter.
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  8. #8
    Pretty much every contemporary widebelt already has Star-Delta as standard. At least in my experience. Bobby, you certain yours doesn’t already have it?

    Erik
    Felder USA Territory Representative: Central & South Texas

  9. #9
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    My old 37" 25hp Pioneer WBS would start off of my 30hp RPC, but I had to hit the start button twice. The first time that I'd hit the button on the sander it would spin up around 75% of the way, and then time out and stop. What I discovered was that if I hit the start button a second time before the motor had time to slow all the way back down, it would spin it up to 100% and would work fine.

    I really had to have my finger hovering over the button though so that I could immediately push start again as soon as it kicked out.

    A lot of the time I ran it off of a 400hp generator, and it had no problems starting. The converter struggled a bit though.

  10. #10
    Quote Originally Posted by Albert Lee View Post
    On my previous wide belt sander, a SCM Uno, it came with factory installed soft starter. From memory it is 7.5kw. On my new sander I fitted a VFD, only for the purpose to overcome the startup current because the main motor is a 18.5kw monster for my supply.
    Hey Albert. What brand and model of VFD do you have on your wide belt and how many horse power is your machine and the VFD?

  11. #11
    Quote Originally Posted by Bill Dufour View Post
    What about turning on more three phase idlers; a big disk sander, lathe and DC fan before starting the sander? They can be switched off after the belt sander is up to speed. How many volt amps supply your RPC?
    Single phase 240 volt needs about 175 amps for 25 hp.
    Bill D.
    Bill are you saying to possibly add another 3 phase motor to my existing RPC? I didnt know that was possible. When I start my wbs I have nothing else running. My Rpc starts my 10hp dust collector without issue although I dont run them at the same time.

    I have my RPC on either a 175amp or 200amp breaker with oversized wire. Everything was over speced on installation.

  12. #12
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    Quote Originally Posted by Bobby Robbinett View Post
    Hey Albert. What brand and model of VFD do you have on your wide belt and how many horse power is your machine and the VFD?
    My VFD is Danfoss VLT2882, the sander is 18.5kw. I had to hire an industrial electrician to do the job properly. Never had an issue with it so far it was installed 6-7 years ago

  13. #13
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    Is the RPC rated to start a 10 hp motor and what are the single phase input amps into it? My 10 hp Kay or 10 hp Phase Perfect starts my 12 hp SCM widebelt. Starting another machine and leaving it on at idle may help to start the WB. Seems counterintuitive but the second motor running helps the system. If the amperage into the RPC is high enough to max out the unit, the temporary spike on start up should not trip a breaker. When the input amps are low or the rpc undersized, the slow ramp up time can lengthen the spike and cause the breaker to trip but normally, a rpc rated to start a hard starting 10 hp motor should have no problem with a WB as they are a medium start compared to a compressor for instance. Dave

  14. #14
    there is a ballast effect on running more machines no one talks about it ive found no info, it exists as the people that built mine told me about it. To test it I once ran five machines, that and a 10 HP roto all running drew 23 amps. I think the roto alone drew 17.6 amps. When more run its better. The thing is you are supposed to start your largest motor first so dont see how that helps in this case. Wish the company I dealt with was still around id call and ask.

    I was in a shop once where a guy had a home made roto, it was started with a rope, some old giant motor and he got it spinning by pulling it with the rope and then it carried on, sort of like what Scott said about second time starting while it was still spinning.
    Last edited by Warren Lake; 07-21-2021 at 10:16 AM.

  15. Kind of late here but yes you can find soft starters for your application usually in the $250 to $400 range. I have one on my 3HP planer as I didn't like the instant load on the drive belt. It's an Allen Bradley soft starter made for single phase 240V applications. The selection your size is even greater.

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