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ceestyle
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Join Date: Feb 2009
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Speed Control for Capacitor Motor

02/07/2009 12:39 AM

I've got a capacitor-driven motor - this guy: http://www.waveplumbing.com/store/index.php?main_page=product_info&cPath=55_80&products_id=159

What is the best way to control the speed of the fan? I have a speedster speed control (http://www.amazon.com/Speedster-Grounded-Variable-Speed-Controller/dp/B000HQAVNI) which seems to work proportionally, but is designed for brush motors. Is it dangerous to use this control, or will it shorten the life of the fan?

If I need another type of control, what do I need?
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dbt
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#1

Re: Speed Control for Capacitor Motor

02/07/2009 4:45 AM

Control speed of Single phase induction motor is quite complicated than 3 phase motor. Drives normally are not available in the market.

With your application, It looks like a ventilation fan. I propose you should use air inlet damper control. It is easier and less risk than control speed of fan. With single phase motor run low speed is easy get fire.

dbt
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JRaef
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#2

Re: Speed Control for Capacitor Motor

02/07/2009 5:49 PM

That kind of speed control simply lowers the voltage to the motor. The motor description doesn't really say enough to be sure, but t in likely a capacitor start-capacitor run motor. If so, the speed controller will appear to work on your motor for a time, but is probably damaging it. Your motor will not last long and in failing will likely also damage the sped controller as well.

There is no effective way to safely vary the speed of a capacitor start motor. If that is what you have, you are relegated to flow control as mentioned above.

If however is it what is called a "Permnent Spit Capacitor" (PSC) type motor, you can buy what is called a "Variable Frequency Drive" (VFD) to run it. But be verycareful here. You have a single phase motor, so you need to look for a "Single Phase OUTPUT" VFD. There are a lot of VFDs that take a 1 phase INPUT, but produce a 3 phase output. You CANNOT use that type. There are a small handfull of VFD manufacturers who provide a version that has a single phase output. Those kind ONLY work on PSC and "Shaded Pole" AC motors.

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FKIA
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#3

Re: Speed Control for Capacitor Motor

02/08/2009 9:33 AM

Your referenced web page does not give sufficient information on the fan motor other than the capacitor is enclosed. It sounds to me from the specs given, that the motor is of the "PSC" design. That type of motor is speed controllable with a device such as Grainger's #1DGV1 about $25. BUT, you will have to check it out on your end as you have the motor.

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ceestyle
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#4

Re: Speed Control for Capacitor Motor

02/08/2009 3:58 PM

First, thanks for the replies.

The reason I don't want to control air flow via vents and other air handling techniques is that I want to reduce its energy consumption and the noise level when the maximum output is not required.

I think the first step is to determine exactly what kind of motor this is. I'm sure it's not a cap-start brush motor. The manual says :

"These Panasonic IN-LINE Fan models use a sirocco fan driven by a capacitor motor"

It also says:

"Do not use this unit with any solid-state control device"

If anyone knows for sure what I'm dealing with, that is the next required piece of information. Otherwise, I'll probably take 'er apart and figure it out for myself. If someone has a few specifics on what I'm looking for, that would help. Otherwise, stay tuned ...
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ceestyle
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#5

Re: Speed Control for Capacitor Motor

02/08/2009 4:14 PM

First, thanks for the replies.

The reason I don't want to control air flow via vents and other air handling techniques is that I want to reduce its energy consumption and the noise level when the maximum output is not required.

Sorry for the double-post ... the first was marked off-topic somehow. Operator error, I'm sure.

I think the first step is to determine exactly what kind of motor this is. I'm sure it's not a cap-start brush motor. The manual says :

"These Panasonic IN-LINE Fan models use a sirocco fan driven by a capacitor motor"

It also says:

"Do not use this unit with any solid-state control device"

If anyone knows for sure what I'm dealing with, that is the next required piece of information. Otherwise, I'll probably take 'er apart and figure it out for myself. If someone has a few specifics on what I'm looking for, that would help. Otherwise, stay tuned ...
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ceestyle
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#6

Re: Speed Control for Capacitor Motor

02/08/2009 9:24 PM

Okay. So poking around with a multimeter, I've discovered it's a PSC, according to circuit diagrams I've seen here: http://www.allaboutcircuits.com/vol_2/chpt_13/9.html

The question now is whether I need VFD, or if simply modulating the AC voltage will be okay - at least from a safety standpoint.
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JRaef
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#7
In reply to #6

Re: Speed Control for Capacitor Motor

02/09/2009 2:53 AM

You need a VFD. If you only lower the voltage, the torque drops off at the square of the applied voltage and long before it slows noticeably, the slip will increase and the motor will pull more current, overloading it.

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morphic
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#8

Re: Speed Control for Capacitor Motor

04/22/2012 7:44 PM

Based on this thread, I purchased the the 1DGV1, as I have the same fan as the OP - the Panasonic WhisperLine FV-30NLF1, to be exact. Unfortunately, this controller causes the fan to produce a very loud humming noise. Any other suggestions for what controller to use? Thanks!

[Edit] Here's a link to the fan's manual - note the electrical wiring diagrams (http://service.us.panasonic.com/OPERMANPDF/FV10NLF1.pdf)
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JRaef
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#9

Re: Speed Control for Capacitor Motor

04/23/2012 9:50 PM

LOL, 3 years later...

Do a web search for Invertek. That is the only thing that will work on that motor. It will cost you more than the fan, but after waiting 3 years, I suppose you REALLY want it now!

http://www.globalspec.com/productfinder/findproducts?query=invertek

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