add Soft Start on Cyclone?

[Erik Christensen]

I posed this exact question to Ed the original clearvue guy a few years ago. He didn't have a hard answer but did say they had one they used for testing - I think the impellers but could have been the finished cyclones - that got started a dozen or more times an hour (every 5 minutes!) for 8 hours a day and had been happy for over a year.

I got from that conversation that as long as I doing something less than that I would be fine. I sure hope so as mine is buried in the overhead in a muffled closet and would be a world class PITA to swap out.

[David Castor]

Just to clarify one point - starting a motor on a soft starter does not really reduce the heat produced in the motor during the start. It does reduce the starting torque and this may be easier on the driven equipment (fan, blower, etc). Starting on a VFD is different and it does drastically reduce the heating in the motor during acceleration. The motor does not really go through a start when on a VFD - it just runs up from 0 Hz to whatever speed is desired, with the VFD maintaining a fairly constant motor slip as it accelerates. If too frequent starting is causing a motor to overheat and fail, a VFD will usually solve the problem - a soft starter probably will not.

[Noah Katz]

You can lessen the start-up current by completely blocking the inlet with a gate.
Compressors (huge industrial ones) use this on start-up. The reason is you are not moving and compressing air, hence less current.
Once it is running, open the inlet.

Is there evidence to support this or is it speculation?

I believe the problem is the huge rotational inertia of the impeller and the energy it takes to get it up to speed, not pushing air.

The HP required to push air through a centrifugal blower increases with the square (or is it cube) of RPM.

Therefore there is very little load at lower RPM, and perhaps nothing significant until after the start windings have kicked out.

Speaking of which, I don't believe it's the running windings that are a concern, but the start caps, centrifugal switch contacts, and maybe the start windings.

A VFD only works on 3-ph motors, which have none of those things, so if you have a 3-ph motor I don't think there's a concern to begin with.

Not for the motor anyway; if one is being used as a phase converter, a slow rampup is a good idea because there are caps inside which, like 1-ph motor caps, are rated for a certain number of starts per hour.

[hank dekeyser]

Once again I am baffled by all the hoopla about "soft-start" and "my DC motor is gonna burn up" etc, etc, etc. I've been running my cyclone whenever I need it on and off not caring for how long it runs or when it last ran etc. for well over 10 years now with a Leeson 5hp motor and guess what ? It still works when I turn the switch, day in- day out - every day. It's burried in the rafters in a closet no less. No ventilation, no fancy nuthin'- If I manage to let the smoke out of it, I'll get it rebuilt and keep on abusing it like I have been. I like spending my money on tools I need rather than worrying that the sky is fallling- my 2 cents

[Myk Rian]

Is there evidence to support this or is it speculation?

For 35 years, I worked as an Instrumentation Journeyman Leader at Ford Motor Company, Rouge plant, Dearborn, Mi. It was my job to make sure compressor controls worked, correctly.
I worked in every building and tunnel in the entire 1200 acres of the plant, plus other plants.

Cases in point;

The oxygen plant.
We produced liquid O2 as a final product. The main compressor was driven by a 5000hp motor. It produced 70 psi air pressure to the plant. A 32" inlet pipe fed it from the filter house.
It was started with the intake vanes closed. To do otherwise the breakers would trip. It was designed that way.

After producing the liquid O2, it was pumped to a 40' diameter ball storage tank. To turn it back to a gaseous state, it was pumped into a steam heated vaporizer, then to 1000hp compressors producing 450psi @ 45,000 cfm. The compressors were started with the intake vanes closed. To do otherwise the breakers would trip. Etc. Etc. The gaseous O2 was fed to the basic oxygen furnace where steel was produced.

A2 compressor station.
This compressor fed the south west 1/4 of the Rouge plant. A 2000hp motor turning a turbine compressor, producing 120 psi plant air. It was started with the intake vanes closed. To do otherwise, blah, blah, blah.

It doesn't matter the size of a compressor, or fan. Huge industrial, or home shop, the same rules apply. It just isn't done in a home shop because you aren't drawing current measured in thousands of amps, at 13,200 volts.

Need I say more?

[Will Blick]

From Jerry, new ClearVue Owner

> It is not recommended to start/stop more than 5 times per hour. And make sure the impeller has come to a complete stop.


Erik, that is great info, thx for sharing...sounds like you are in the same situation I am in... replacing my motor would be 15 hour job, in awkward positions 14ft high.... dumb planning by others who help build my shop... oh well....


> I don't believe it's the running windings that are a concern, but the start caps, centrifugal switch contacts, and maybe the start windings.


Agreed, as I mentioned, my motor would never burn out from "mileage".... as mentioned by a previous poster, they do make single phase and two phase VFD / soft starters...


Hank, that is the best testimony I have heard yet, and what I was hoping to hear....thx... I was not aware ClearVue has been around 10 years, have you really had yours that long? Do you use your ClearVue daily? How many start /stops on avg. per day?

[Jon van der Linden]

Read my last sentence.

LOL My point is that ALL stationary machines have significant amounts of dust that aren't immediately collected, there is no "if." My last machine has a 12" pipe, it pulls in a lot, but I still leave it open for a while. Keeping the ambient air clean is really important in an enclosed space.

[ian maybury]

I'm another that's gone the VFD/220V 3 phase route with a Clear Vue fan and cyclone, in my case primarily to reduce the start up amps draw on the fairly low 60A supply limit we have. Can't say how well it will work, as it's still mid install.

There's quite a few advantages to using a VFD though:

1. Reduced current draw on start up. (ability to ramp the start)
2. Ability to tune RPM to suit system and specific machine requirements.
3. Ease of hooking up a remote/radio start stop switch and other controls - speed adjustment, E stop and the like. (no need for heavy relays etc - use the inverter's 24V control inputs)
4. Toleration of frequent start/stops. (from this thread)
5. Lower cost 3 phase motors..
6. Gets over the issue of 5hp single phase motors often not being available in UK/Ireland. (the current draw on start up is too high for most domestic installations)
7. Speculative, but it probably greatly adds to the available range of control functions - it probably wouldn't be too hard to use a small PLC or something to arrange a ramped start, selection of stock speed settings and the like.

The downside is that it's more expensive, and installation takes a bit of time and work - vented enclosure, shielded and grounded power cables, wiring the controls etc

It's quite normal by the way for servo actuated inlet vanes to be fitted to the fans in air handling units to reduce the current draw on start up - they are closed when the motor starts, and normally don't open until the motor is up to speed. (their operation can be switched by the star/delta start mechanism I seem to recall)

ian

[Alan Schaffter]

LOL My point is that ALL stationary machines have significant amounts of dust that aren't immediately collected, there is no "if." My last machine has a 12" pipe, it pulls in a lot, but I still leave it open for a while. Keeping the ambient air clean is really important in an enclosed space.

I won't even go there- won't talk about those ceiling hung "dust circulators."

[CPeter James]

Does this mean that I should not start and stop my table saw, lathe, drill press, jointer, more than a few times each hour? For safety reasons, I often start and stop them many times when using them. If I am using my 5 hp IR Type 30 air compressor to run a sand blaster or air sander, it starts and stops quite frequently. I do not understand why DC systems should be different.

CPeter

[Alan Schaffter]

Does this mean that I should not start and stop my table saw, lathe, drill press, jointer, more than a few times each hour? For safety reasons, I often start and stop them many times when using them. If I am using my 5 hp IR Type 30 air compressor to run a sand blaster or air sander, it starts and stops quite frequently. I do not understand why DC systems should be different.

CPeter

The difference is that the DC motor is under load trying to move air from the get go, while the others aren't under load until you start working stock.

That being said, I don't see what the fuss is all about. You really need to be one speedy or disorganized woodworker to cycle your DC so often it will damage the motor. There is not much difference between 5 times per hour and 7, 8, etc. times per hour, especially if during the next hour you cycle it only 3 times!

I removed my 3 hp DC motor from an old Grizzly dust collector I got from a defunct lumber yard- it is very old with no model number, so it could be 20 years old now. They had it for many years and really abused it- it was so caked with dust that I needed to use a chisel first to clean it. I've been running it for ten years never paying attention to the number/frequency of cycles. Other than replacing the bearings once and polishing the contacts on the centrifugal switch, it has had no problems and continues to work great!

[Will Blick]

Peter, it was made clear many times in this thread, there is no harm in starting TS frequently, as its fully unloaded, this is obvious from the sound alone, as the blade seems to instantaneously make it to full run speed... no stress at all... like you, for safety reasons, I start / stop mine very often, usually to remove small peices before continuing.... same true with all the other tools you mentioned.... the DC as mentioned is unique, evidenced by its struggle to get to full run speed on start up....

> I don't see what the fuss is all about.

"fuss" ? it was a question... a discovery process, the stated reason were because

1) no data was provided for start / stops per hour on the motor
2) the location of the motor made it VERY difficult to replace, otherwise, I wouldn't care, as I would just wing it, and let the motor life play out....

through this thread, it was obvious, the answers were not universally understood... I thought that was the purpose of forums, to discuss these issues? To me, this was an educational thread, I don't consider it "fuss'in"..... Instead, I would classify it as "learning" as there was some great contributions.

But, as commonplace, a thread eventually ends with the classic quote.....

"whats this all about??"
"why the fuss'in"

[CPeter James]

I was not being sarcastic, just curious as to the difference. I will say that my compressor starting against 150 PSI tank pressure starts hard. IR engineered it that way, but I did put an unloader on the head and intercooler to help it. Also, while I have a fairly small band saw, those larger ones, say 30", 36" and 40" come up to speed pretty slowly as well. On electric motors, there are a lot of unknowns and several urban legends. I have followed the thread about the resistor on the start capacitor on the Baldor motors closely and want to follow up on that because, mine has a really hard bank on shut down and it comes just at the time that the start contacts would be closing leading to the inrush of current to the field.

CPeter

[Noah Katz]

It doesn't matter the size of a compressor, or fan.

You may have missed my point, which I admit is a bit academic..

A compressor and a fan may both have high starting loads, but for different reasons – the former because of high inertia and the latter because of high pressure.

I was questioning the assertion that moving air is a significant part of the starting load of a fan.

[Alan Schaffter]

Peter, it was made clear many times in this thread, there is no harm in starting TS frequently, as its fully unloaded, this is obvious from the sound alone, as the blade seems to instantaneously make it to full run speed... no stress at all... like you, for safety reasons, I start / stop mine very often, usually to remove small pieces before continuing.... same true with all the other tools you mentioned.... the DC as mentioned is unique, evidenced by its struggle to get to full run speed on start up....

> I don't see what the fuss is all about.

"fuss" ? it was a question... a discovery process, the stated reason were because

1) no data was provided for start / stops per hour on the motor
2) the location of the motor made it VERY difficult to replace, otherwise, I wouldn't care, as I would just wing it, and let the motor life play out....

Maybe fuss was the wrong term, but lets look at the facts and evidence- previous posts on here and other forums have reported the info and quotes from motor manufacturers as to the "recommended start frequency." Has anyone ever seen a start frequency caution in a DC manual? I doubt that is because they want their DC's to fail so you must buy a new one. Remember, everyone operates a tool differently and start frequency can be computed differently! 10 starts in 15 minutes may not be all that bad if the tool is not used again for an hour or it runs continuously for a half hour. No motors used with home and small commercial shop DCs that I know of have ever included soft start. I have never seen a report (5 different forums over 10 years) of a DC motor failing due to excessive start cycles and that includes a lot of low quality imports. In fact the only DC I have ever read reports about where a motor (and/or switch) failed was the HF and I suspect it was not being used as designed!

My DC blower/motor isn't hidden away, but at nearly 10' in the air, repair is it a task I don't take lightly. It doesn't have or need soft start and I don't count starts-

through this thread, it was obvious, the answers were not universally understood... I thought that was the purpose of forums, to discuss these issues? To me, this was an educational thread, I don't consider it "fuss'in"..... Instead, I would classify it as "learning" as there was some great contributions.

But, as commonplace, a thread eventually ends with the classic quote.....

"whats this all about??"
"why the fuss'in"

But, you must separate the wheat from the chaff, and if folks would take time to do some research, they would find, to quote a common trial objection, "Asked and answered."