motor replacement for dust extractor

[Albert Lee]

After a week of using my dust extractor with the new ducting, I have come to the conclusion that the dust extractor's motor is inadequate for the impeller.

it is a 4kw motor driving a 20 inch impeller.

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I am planning to swap it to a larger motor say either 5.5kw or 7.5kw. I am not sure if 5.5kw will suffice and if 7.5kw will be too large.

Has anyone done this before? mine look pretty simple to replace, loosen the nut, take out the impeller, loosen the bolt/nut that holds the motor, lower the motor, put new motor up, tighten the fixing bolt/nut, put impeller back on, tighten the nut.

I have a small crane that I can use so should be pretty simple to lower the motor and uplift the motor.

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or should I just sell the extractor and buy new. a new one will cost in between 7000 USD and 10000 USD for a 5.5kw+ unit, a new motor is only about 300-400 USD for 5.5kw

[Phil Thien]

Well how did you come to the conclusion that the current motor is inadequate? If the current draw exceeded the nameplate rating, then you should be able to use whatever reading you got to help properly size a replacement motor.

[Chris Parks]

After a week of using my dust extractor with the new ducting, I have come to the conclusion that the dust extractor's motor is inadequate for the impeller.

it is a 4kw motor driving a 20 inch impeller.

289211



I am planning to swap it to a larger motor say either 5.5kw or 7.5kw. I am not sure if 5.5kw will suffice and if 7.5kw will be too large.

Has anyone done this before? mine look pretty simple to replace, loosen the nut, take out the impeller, loosen the bolt/nut that holds the motor, lower the motor, put new motor up, tighten the fixing bolt/nut, put impeller back on, tighten the nut.

I have a small crane that I can use so should be pretty simple to lower the motor and uplift the motor.

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or should I just sell the extractor and buy new. a new one will cost in between 7000 USD and 10000 USD for a 5.5kw+ unit, a new motor is only about 300-400 USD for 5.5kw

A single Clearvue Max or if operating multiple machines even two CV Max won't cost 10K. I did the calcs for importing into NZ for several people about twelve months ago and that was sending the units straight from the US and billing from Oz. The big advantage is no bags and if exhausting straight to atmosphere no filters.

[Rod Sheridan]

Replacing the motor with a larger one won't do anything unless you increase shaft speed (which may not be safe).

Are you having problems with the motor overheating?

Regards, Rod.

[Chris Parks]

Replacing the motor with a larger one won't do anything unless you increase shaft speed (which may not be safe).

Are you having problems with the motor overheating?

Regards, Rod.

Rod is correct and another proviso is if the fan curve will be effective at double the RPM. When designing a fan/impeller there is no reason to make the effective range very broad as the motors generally operate at only one speed.

[Albert Lee]

hi Chris. yes I know the pricing to have it sitting in my house is close to $3000 USD for a CVMax after tax/freight/duty....etc

I dont like the plastic/MDF component of the ClearVue.... besides, I have already invested in the ducting thats designed for one large unit.

I have seen a Taiwanese copy of the Felder RL series. pricing is 1/2 of the comparable Felder unit.

[Chris Parks]

The CV is proven and will run large duct diameters. What you see as a problem, it being a kit to be assembled, is an advantage as it can be custom installed in many ways. I have supplied dozens commercially and a lot of them running 24 hours a day and the company is over the moon with the results and are having no problems with the "plastic" or MDF. Those units are running coal dust through them and some are in Mongolia, god knows what the Mongols will use them for when the company leaves!! I have no commercial interest in recommending the CV as I am no longer the distributor and am just passing on my experience. It is a very tough unit and has proven commercial success all over the world.

[David Kumm]

Albert, as I remember the thread when you bought the collector, it was the motor size relative to the impeller that surprised us. Wasn't the rpm slow on the motor? You should monitor the amp draw with the gates open and see what is needed. The motor swap won't change the cfm produced unless you change to a faster rpm motor which would need to be larger hp. You would likely need a larger diameter taper lock bushing as the shaft will be larger and you might need to drill new holes to mount the motor of the C frame is different. What you have is a good design if you get the cfm and motor thing straightened out. DAve

[Albert Lee]

David I think I will just sell this one and get a larger DC, either a CVMax or something thats in the realm of 7.5hp-10hp.

[Tim Campbell]

Albert,

If I remember correctly, your motor is 4 pole running at about 1400 RPM. I believe this will be the limitation on your system. Replacing the motor with a 2 pole motor running at 2850 RPM would make a considerable improvement. Depending on how much air is being moved, you might not even need to increase the HP of the motor.

The only downside of this will be the increase in noise which will come from the additional speed. You could also consider adding a VFD which will enable you to select a range of speeds / airflow to match your particular machine and setup.

I'm no expert on electric motors, and others may wish to comment on this, but it may even be possible to rewire your existing motor to 2 pole or even use a VFD to run your existing motor at more than 50Hz to increase its RPM above 1400.

[David Kumm]

Albert, what you have is a large commercial system. It just runs too slow. You won't be able to speed that motor up enough to get you the cfm within the amp draw so you will need to replace the motor. That impeller will need at least a 7.5 and could stand a 10 when approaching 2800 rpm. You should use a vfd to dial in the cfm but when you do that you will have a great system. It will be loud but due to the impeller design it will outperform most systems when under pressure. I would not give up on what is a well built machine. I run the same blower but only 16" at 3600 rpm and it doesn't fully load my 7.5 hp motor. Your 20" at 2800 will need more amps and deliver more cfm. If you are planning on 10 hp, that is what I'd use with a vfd to slow it down a little depending on your needs and readings. Dave

[Chris Parks]

If the fan/impeller will perform at the 2800 then change the motor and with a VFD it can only enhance the whole thing. The only proviso is have you got the electricity capacity to feed the larger motor as it will require a substantial supply to run it. The VFD will minimise the power requirement due to it being a soft start, hard starts mean high amp loads.