# 75 hp soft starter



## Peewee0413 (Oct 18, 2012)

How often do you start and stop the saw?


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## hydro (Aug 21, 2009)

Well not my saw as I'm the electrician but I'm pretty sure he'll more or less start it in the morning and run it till the end of the day. Maybe shutting it off at lunch.


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## Peewee0413 (Oct 18, 2012)

It wont hurt to put one in. Probably won't lessen the motor life any/much if you don't put one in. Just a hunch, but it may save belts more than motor life. I may be wrong since I have no idea how belt tension is made during startup nor running


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## hydro (Aug 21, 2009)

Ya I'm not sure about tension but I do know the motor produces about 195ftlbs of torque when running. But you have made me think about the fact that it only starts and stops a few times a day so now I'm reconsidering


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## erics37 (May 7, 2009)

What kind of mill is it? What is the saw cutting?

I worked at a plywood mill for several years, and they had a great big saw like that to cut dry veneer in half for the glue spreader crews. That thing got started and stopped several times an hour.


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## hydro (Aug 21, 2009)

It's a sawmill so logs are loaded on a carriage and fed into the saw. It's not like they start it up make a cut and shut it down I think it stays running


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## erics37 (May 7, 2009)

hydro said:


> It's a sawmill so logs are loaded on a carriage and fed into the saw. It's not like they start it up make a cut and shut it down I think it stays running


I concur; a saw like that would pretty much run the whole shift.


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## hydro (Aug 21, 2009)

So I guess the consensus might be for the amount the saw starts and stops it probably isn't necassary


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## Peewee0413 (Oct 18, 2012)

Yup.


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## micromind (Aug 11, 2007)

I'd bet that more than half of the 75HP motors that I connect start across the lines. Belt drive, direct drive, etc.

Unless they're grossly undersized, the drive belts will easily handle the starting torque.


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## hydro (Aug 21, 2009)

micromind said:


> I'd bet that more than half of the 75HP motors that I connect start across the lines. Belt drive, direct drive, etc.
> 
> Unless they're grossly undersized, the drive belts will easily handle the starting torque.


I'm not sure if I 100% agree. I installed a soft start for the same customer on a 100 hp motor running the top head on a giant 4 sided planer because he was shredding belts. 10 v belt drive to


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## BBQ (Nov 16, 2010)

I would go with a standard starter and be done with it .... unless the power companies terms of service limit across the line starters at that HP.


You can buy a lot of belts for the price of a 75 HP VFD.


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## Peewee0413 (Oct 18, 2012)

If belts can and or will shear the ramp up of a soft start may be worth the price. Or buy high dollar belts that is more than capable. Once the blade is in motion, the stress is less than initial start up. Kinda like once you get a car rolling its easier to push. (Inertia) I installed motor/gearbox for a paddle wheel. 7.5 hp motor, once the water got to speed the calcs showed 3.0 hp. Moving water pushes the paddle wheel, thus using less power. (Just making conversation of motors and movement.) Same thing with a pump jack(nodding donkey) in the oil fields.


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## JRaef (Mar 23, 2009)

hydro said:


> It's a sawmill so logs are loaded on a carriage and fed into the saw. It's not like they start it up make a cut and shut it down I think it stays running


Sounds like a head rig then. Talk to the sawyers. They probably have to change the blades 3-4 times per shift, it's usually done during breaks for the operators, so the saw will be shut down for that every time. The soft starter will reduce the mechanical wear and tear on the motor, belts, journals, everything. I would do it. Also, starting torque can pull the blade out of alignment (assuming a band saw here), a soft starter can help to avoid that, which increases productivity.

Also on a 52" saw, the wheels have a lot of inertia and using a soft starter with a brake option can reduce the time the sawyers have to wait for the saw to coast to a stop, which may increase productivity.

<Sniff> I used to live in Seattle and did a lot of saw mill work in Oregon, Washington and BC. But since moving to California, cutting trees is such a foreign concept here I have only set foot in one mill in the last 5 years. I miss it a lot, especially the smell of fresh cut wood.


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## hydro (Aug 21, 2009)

It's actually a circular saw blade not a bandsaw. It's a small operation with only the owner and a help. I guess they would stop the blade for sharpening but I don't know how often they would per day. Plus I'm sure they would sharpen during breaks. Really though starting 3-4 times a day would that really be enough to destroy the belts?


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## Peewee0413 (Oct 18, 2012)

I doubt it. Just wire it up and call it a day.. if problems occur put in a soft start.


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## hydro (Aug 21, 2009)

Well if nothing else I could put in an I line starter and if it don't work I can say the old I told ya so


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## John Valdes (May 17, 2007)

Weg sells a din rail mount soft start with built in bypass for close to the price of a NEMA starter.
It would be a mistake to buy a contactor before you get a quote on the SS.
Take a look at the picture of the SSW series SS.
I/O on board. So it takes the place of the contactor with no additional wiring required.
Take your NEMA contactor, heaters and OL relay and I bet you come out better on the soft start.


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## hydro (Aug 21, 2009)

You say there the same price as an I line?!! Do they make them big enough for 75hp motors?


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## Peewee0413 (Oct 18, 2012)

They make 600v 75 hp amp soft starts. Its 2013 they make just about anything. The only problem I ever have is when it comes to buying instruments. Sometimes it's hard to find an instrument that does what you want it to do.


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## Cow (Jan 16, 2008)

http://www.factorymation.com/Products/Soft_Starters


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## Peewee0413 (Oct 18, 2012)

I seen a large Weg before. Might have been 200 hp, on a batching system.


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## hydro (Aug 21, 2009)

Can't argue with those prices at all. Think I might have sold me a soft starter


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