How Do I Test A 90VDC Treadmill Motor? - Electrical - Page 2 - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum How do I test a 90VDC treadmill motor?
 Register Blogs Articles Rewards Search Today's Posts Mark Forums Read

04-17-2009, 11:07 AM   #16
Member

Join Date: Jun 2007
Posts: 3,788
Rewards Points: 236

DC motors are comprised of an armature and a field. The field can be a magnet or wound like an AC motor. DC motors come in a few different variations. (For another day). The armature receives the DC voltage and the field repels it. That is why it turns. By lowering the DC voltage to the armature the motor will slow down. When the voltage increases to the armature the motor speeds up proportionally to the voltage. This is how you basically control a DC motor.
The DC motor can achieve higher base (nameplate) speeds by whats called field weakening. Lowering the field voltage. This is very basic DC motor technology. This what I know, and I do not know everything.

AC motors are comprised of a rotor and stator. The rotor is built with iron bars and looks like a single barrel of iron. The stator looks very similar to a wound DC motor field depending on the motor.
To achieve suitable speed control of an AC motor you must proportionally adjust hertz and voltage. For example. 460 volt, 1800 rpm, 60 Hz motor. If you apply 460 volts at 60 Hz the motor will run at base (nameplate) speed, 1800. If you apply 240 volts at 30 Hz the motor will run at 900 rpm. If you apply 120 volts at 15 Hz the motor will run at 450 rpm.
This is where Pulse Width Modulation comes into play. AC inverters (VFD's Drives) input AC voltage, then convert the AC to DC. It is stored in the DC bus (800 volts DC at 460 volt AC input) The drive then uses whats called IGBT's, capacitors and logic to transform this DC voltage into a simulated AC signwave. This is PWM at it's most basic description.
Keep in mind all the values above are expressed in general terms and can fluctuate a few volts and rpm's here and there.

Thats all I have my friend. Let me know what you think........John Valdes

http://www.electriciantalk.com/f28/ Check this forum out. We can discuss this further there. This is a DIY forum and I think this discussion should go there.

Last edited by J. V.; 04-17-2009 at 11:13 AM.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post marc Electrical 13 02-05-2009 05:26 PM dgr68 Electrical 8 01-04-2009 05:13 PM Timster Appliances 12 11-25-2008 03:26 PM thothtp HVAC 5 06-08-2008 06:30 PM

Top of Page | View New Posts