Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-17-2009, 11:07 AM   #16
Member
 
Join Date: Jun 2007
Posts: 3,503
Share |
Default

How do I test a 90VDC treadmill motor?


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.
J. V. is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
90vdc motor to 110 outlet marc Electrical 13 02-05-2009 05:26 PM
Motor control wiring problem dgr68 Electrical 8 01-04-2009 05:13 PM
How to test pond pump motor for current leakage? Timster Appliances 12 11-25-2008 03:26 PM
Replacing a Condenser Fan Motor thothtp HVAC 5 06-08-2008 06:30 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.