How to convert 2hp AC blower motor to variable speed
How to convert 2hp AC blower motor to variable speed
(OP)
I have a 2HP 240V blower motor for which I would like to vary the speed from my plc. The motor is a standard HVAC type blower which is belt-driven from a motor.
Any inexpensive suggestions as to how I may use this motor or do I have to replace it with another type.
I'm in the process of upgrading the controls on this piece of equipment (Dectron Dry-0-Tron). It controls the environment in a swimming pool room.
Any inexpensive suggestions as to how I may use this motor or do I have to replace it with another type.
I'm in the process of upgrading the controls on this piece of equipment (Dectron Dry-0-Tron). It controls the environment in a swimming pool room.





RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
If the blower is driven by a permanent-split-capacitor {PSC} 1ø motor, simple triac/SCR phase control may be applicable.
RE: How to convert 2hp AC blower motor to variable speed
<nbucska@pcperipherals.com>
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
if you have enough budget for this modifications, i will recommend a VFD with inverter duty motor...you can use a miniature PLC to control the VFD's preset speed which i believe up to seven settings on standard VFD's...you can program the PLC for whatever time you want the speeds to kick in..
dydt
RE: How to convert 2hp AC blower motor to variable speed
Before you can act on any of these suggestions, you need to determine (and post) wether it is a single phase or 3 phase motor. If it is single phase as I suspect, the VFD suggestions are mostly invalid unless you replace the motor with a 3 phase version and that sounds a bit drastic for your purposes.
The simplest way to tell is to look at the circuit breaker or fuse box that is feeding power to this blower. If it is a 2 pole breaker or 2 fuses, it is single phase. If it is 3 poles or 3 fuses it is 3 phase. Don't trust just counting wires since ground wires are sometimes mislabeled.
If it is 3 phase, I suggest just using an inexpensive soft start device since you may not need to vary the speed continuously. At 2HP 240V however, there is not much of a cost difference to upgrade to a VFD, just more complex.
If it is single phase it is more complicated because of the different types of single phase motors. Some can be used with electronic controls, some can't. Find out and re-post.
Subvert the dominant paradigm... Think first, then act!
RE: How to convert 2hp AC blower motor to variable speed
What kind of noise problems are you dealing with?
RE: How to convert 2hp AC blower motor to variable speed
Keep in mind -- i only have 24VDC digital inputs, digital output relays and 4-20mA inputs in the PLC. No analog outputs.
RE: How to convert 2hp AC blower motor to variable speed
Is the duct "oil-canning?"
RE: How to convert 2hp AC blower motor to variable speed
Looking at the motor (not being a motor expert) it looks like a normal one with two coil size humps on the top of it. I'm hoping this will give a clue to the type of motor I have and my options. If only I could ramp this motor up to speed. This definately would solve my problem.
Question 1:
Is my description of the motor enough to determine if this motor can be ramped?
Question 2:
If so, what devices would I need to accomplish this?
Thanks
rick
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
Oops.
RE: How to convert 2hp AC blower motor to variable speed
I do not believe that a ceiling-fan controller has adequate capacity.
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
RE: How to convert 2hp AC blower motor to variable speed
I hate to tell you this, but from your description it does appear that you have a permanent split capacitor 1 phase motor and you will not be able to use an electronic soft start device with it. The soft start components would be damaged by the capacitors in the motor. This will also prevent you from using a VFD as well, even if you found one that works on 1 phase motors. I have in the past used a soft start on a temporary fan with full knowledge that it would not last long, but it made the problem go away for a few months anyway. Baldor makes a cheap 1 phase soft start controller that you can simply mount and wire downstream from whatever is controlling your motor now. It may only last a few months, or you might get lucky and it will last a year or so, you never know. Your only alternative electrically is to change out the motor to 3 phase and add a VFD which will convert your 240V 1 phase power to 3 phase for the motor. FDigure $300-500 plus labor minimum.
Another approach would be a "mechanical soft start" clutch device such as a Torque Tamer, shot coupling or fluid coupling that will slowly allow the blower to accelerate even though the motor is started at full speed rapidly. Contact a Power Transmission distributor such as Motion Industries or Kaman Industrial for advice.
That pop you here is probably the sheet metal or even the fiberglass duct "oil canning" as busbar suggested, so another option may be to solve the problem mechanically, perhapse with spray-on sound dampening material or something like that.
Good luck.
Subvert the dominant paradigm... Think first, then act!
RE: How to convert 2hp AC blower motor to variable speed
http://www.toad.net/~jsmeenen/motor.html
http://www.achrnews.com/CDA/ArticleInformation/features/BNP__Features__Item/0,1338,26558,00.html
http://www.braschmfg.com/Download/cabinet.pdf
http://www.lsicsi.com/appnotes_files/body_application_notes.html
etc. for some interesting ideas, perhaps some higher power rated dimmer could perform the motor controls.
RE: How to convert 2hp AC blower motor to variable speed
http://www.varidigm.com/pdf/Approved%20Final%20VSM-CP2%20Data%20Sheet%2015-1003A.pdf
I'm a chemist, not an EE, but this product looks good to me.
~Jeff
RE: How to convert 2hp AC blower motor to variable speed