
how to slow blower motor (or eliminate wooshing)
#1
Posted 26 June 2004 - 01:09 PM
Specs of relevant parts are at the end of this note.
Also: I left the existing foam seal where the blower output extends through the rectangular hole to the heating chamber. Can this be replaced? Where can it be obtained? (also checking: Since the new blower has rubber isolators in its motor mount & the old blower's rubber isolators were decayed, I mounted the new blower upon non-elastic spacers -- a stack of washers -- I hear no hum so assume this is ok)
Blower=grainger 5c97d (lookup on grainger.com)
wheel=12 5/8 x 9 1/2,
opening=13 7/16 x 12 1/4
Motor: 3 speed, rated current=14A @ 120V
1075 RPM, 1HP
Refrigeration capacity: 3T
Furnace: an old and servicable york cimaster 120k BTU
Thanks, Eric
#2
Posted 04 July 2004 - 07:20 PM
Welcome to the forum.
I assume from the information posted, that this is a single phase motor.
Unfortunately, it is not easy to control the speed of a single phase motor. If it were possible, I would recommend that you replace the motor with a three phase motor and use a single phase input three phase output inverter. These are very common and relatively cheap. You would then have total control over the fan speed.
Some fan motors can be controlled by variable voltage controllers. This will not directly control the speed, but will control the torque available. Reducing the torque on a fan, will cause the fan to slow down.
You must not apply a variable voltage controller to a standard induction motor.
Best regards,
Mark Empson | administrator
Skype Contact = markempson | phone +64 274 363 067
LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | Soft Starters
#3
Guest__*
Posted 27 January 2005 - 09:47 AM
Could you pls tell us why not? If the mains frequency were slowed down, (frequency control) the rotor would follow the stator field and also slow down. Obviously it would not run real smooth, since the rotor would be pulled from side to side. This should work if the motor were already running at speed, and then obviously not loaded too much to cause it to stall either?
#4
Posted 27 January 2005 - 06:30 PM
A standard induction motor is not designed to slip very much, infact it is designed to have a low slip. If you reduce the voltage only, you will reduce the torque to a point where the motor will stall. Under these conditions, the motor may run at redduced speed, but the current will be hihg and the slip losses will be very high, you will damage the motor.
If you use a high slip motor, you can vary the speed with voltage control.
To alter the speed of a standard induction motor, you must vary the voltage and the frequency.
Best regards,
Mark Empson | administrator
Skype Contact = markempson | phone +64 274 363 067
LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | Soft Starters
#5
Guest__*
Posted 31 January 2005 - 01:09 PM
Specifically now referring to my single-phase motor, can I use a normal three-phase motor drive controller, on my small single phase motor, (500W) and only connect up one of the phases, to get the frequency control I desire, to control the speed.
[Note: I could attach a fan for forced cooling, and I don't need the motor to run too slowly.]
Would this work?
---James
#6
Posted 31 January 2005 - 04:46 PM
1) No Variable Frequency Drive will allow you to attach only 1 phase to the output. It will trip off on Output Phase Loss immediately, and no drive on the market that I know of allows you to defeat that protection.
2) 120V single phase motors are almost always going to be capacitor start because the capacitors are needed to make the motor start tunring (3 phase motors turn on their own because there is a rotating magnetic field from phase to phase). They have a centrifugal speed switch in them that takes out the capacitors withing miliseconds as the motor speed increases. If a VFD is put on them, the speed does not increase fast enough and the capacitors are left in the circuit too long, damaging the motor, start switch, capacitors and the VFD! Other than that, no problem...
Most likely the reason for the "whooshing" on your intake registers is that this motor is starting at a higher speed than the original. Are you sure you are starting at the lowest speed?
#7
Posted 31 January 2005 - 04:59 PM
http://www.baldor.co.....ols_SoftStart
PS: That link is too long for the format of this form, so you need to copy and paste it into your browser.
#8
Guest__*
Posted 01 February 2005 - 09:44 AM
http://www.anaconsys...11402eagle.html
Am I smoking my socks? or just really confused?
---James
"extract:
Atlantic City, New Jersey January 14, 2002 Today, at the Air Conditioning, Heating and Refrigeration (AHR) Exposition, Anacon Systems introduced the EagleDrive TM Series, of Variable Frequency Drives (VFD's) that connect to worldwide electrical supplies for variable speed control of both Single-Phase and Three-Phase AC Induction Motors. The EagleDrive1 TM Series is an industry-first, designed for use with Single-Phase AC Induction motors and is available in 115V or 230V at power levels up to 1.5 HP. The EagleDrive3 TM Series for Three-Phase AC Induction motors is available in 200 - 240V (1 or 3-phase input) at power levels up to 3.0 HP, and with 380 - 480V (3-phase) at power levels up to 120 HP. Simple programming and an integrated infrared link combine to minimize the overall applied cost of an EagleDrive TM solution."
#9
Posted 03 February 2005 - 01:54 AM
I just remembered that someone else showed me another option. This product also controls 1 phase PSC motors. I don't know anything about them, just that they exist as an alternatie to Anacon.
http://www.hoffmanco...ducts.php?ID=23
The Anacon drive can also be purchased through another comany as a brand-label. http://bardac.com/pa...optidrive7.html
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