Uploaded April 2017 | Updated September 2026, 2 weeks ago
Can an electronically commutated furnace fan motor driven by an external source produce enough voltage and current to present a safety hazard? Would it make a useful source of electrical energy if you were to use it as an alternator? What does the output waveform look like on an oscilloscope?
Electronically Commutated Motors (ECMs) have been growing in popularity for HVAC use. They are brushless DC motors having a permanently magnetized rotor. Their advantage is one of infinitely variable speed as compared to a conventional AC powered induction motor with a limited selection of speed taps. They can also better maintain constant torque under varying load conditions. I first saw one in a residential HVAC system about 20 years ago. Soft startup and shutdown (rather than the sudden, and typically rather loud startup from a conventional AC motor) are also easily enabled by use of an electronically commutated motor.
I'm aware that my electrical terminology isn't strictly accurate at all times. I tend to use terms somewhat interchangeably. Still, you get the idea...and it's not like I'm the only person who has ever done so.
Since it wasn't designed for the generation of electrical energy, I suspect that the motor would eventually overheat under any significant load.
Further reading:
edn.com/design/sensors/4406682/Brushless-DC-Motors---Part-I--Construction-and-Operating-Principles
en.wikipedia.org/wiki/Brushless_DC_electric_motor
http://www.eng.uwi.tt/depts/elec/staff/rdefour/Publications/Development%20of%20Multi-pole%20BLDCM_OA_WebPg.pdf
Can an electronically commutated furnace fan motor driven by an external source produce enough voltage and current to present a safety hazard? Would it make a useful source of electrical energy if you were to use it as an alternator? What does the output waveform look like on an oscilloscope?
Electronically Commutated Motors (ECMs) have been growing in popularity for HVAC use. They are brushless DC motors having a permanently magnetized rotor. Their advantage is one of infinitely variable speed as compared to a conventional AC powered induction motor with a limited selection of speed taps. They can also better maintain constant torque under varying load conditions. I first saw one in a residential HVAC system about 20 years ago. Soft startup and shutdown (rather than the sudden, and typically rather loud startup from a conventional AC motor) are also easily enabled by use of an electronically commutated motor.
I'm aware that my electrical terminology isn't strictly accurate at all times. I tend to use terms somewhat interchangeably. Still, you get the idea...and it's not like I'm the only person who has ever done so.
Since it wasn't designed for the generation of electrical energy, I suspect that the motor would eventually overheat under any significant load.
Further reading:
edn.com/design/sensors/4406682/Brushless-DC-Motors---Part-I--Construction-and-Operating-Principles
en.wikipedia.org/wiki/Brushless_DC_electric_motor
http://www.eng.uwi.tt/depts/elec/staff/rdefour/Publications/Development%20of%20Multi-pole%20BLDCM_OA_WebPg.pdf
