Dc Motor Hum.....

Found a few things on this site, seems like a good info source:
https://www.americancontrolelectronics.com/t-faq.aspx#tech1 ( formerly Minarik)

Why is my motor producing a loud humming/buzzing sound?
If the motor is producing this type of sound, a non-filtered SCR type drive is probably being used to run it. SCR type drives pulse a motor with voltage 120 times per second. The sound that is heard is the magnetic fields energizing and breaking down inside the motor at 120Hz. Although this is normal, a PWM type drive is a good choice if the hum is not acceptable in the application.

What is a line filter?
A line filter is a device typically connected in between the AC line source and the input of a drive. A line filter is designed to prevent electrical noise from entering a drive. Line filters are commonly used in applications where electrical noise is generated, such as in welding applications. SCR type drives are most commonly affected by line noise due to their reliance on a clean AC waveform for switching purposes.


The drive is SCR type, I have an AC line filter from a treadmill, it may help with the pulsing/oscillating, yes?


Why does my motor oscillate / not run smoothly?
  1. IR Comp Adjustment: Most drives have this adjustment. If set too far clockwise the motor will tend to oscillate. Slowly turn the IR Comp trim pot in the counter clockwise direction until the oscillation stops.
  2. Speed command signal: An unstable speed command signal to the drive can cause the motor not to run smoothly. Remove the command signal from the drive and use a potentiometer instead. If the motor becomes smooth, the external speed command signal was the source of the problem.
  3. Change in load: In most applications a drive can be tuned to run a motor smoothly and compensate for changes in load. But when loads change abruptly, the IR Comp circuit cannot respond fast enough. Make sure there are no mechanical problems in the operation that can cause these abrupt changes in load. A good way to check this is to simply remove the load from the motor and observe how it runs. If operation becomes smooth, you most likely have a mechanical obstruction.
  4. Motor brushes: If using a permanent magnet motor, inspect the brushes for excessive wear or irregular wear. It also a good idea to blow compressed air into the brush housing to clean out any carbon build up. If possible, turn the motor shaft as you blow compressed air into the brush compartment.
  5. Max speed too high: Having the output voltage to the motor set too high can cause some drives armature output to become unstable. Do not try to run a motor that exceeds the armature voltage that is available to use. For example, you can’t run a 180VDC rated motor when you power a drive with 115VAC.

#1 I'll try adjusting the IR comp as noted.
#2 Its running on a speed pot now so does this apply in some way?
#3 Not running under load
#4 Brushes look good, commutator(think thats right) is not shiny copper, maybe carbon build up from the brushes?
#5 I'm running on 230VAC

I'm off to do a little tweaking and take a few pics.

Brian
 
Try backing off the IR comp. The filter won't make any difference: it is mostly to prevent the controller from interfering with other stuff. The commutator normally looks dull.
 
there are speed pots inside along with ir comp...acceleration..deceleration..min speed ..max speed..and one more that i cant think of right now...on most big controllers ..but you haven't posted a pic yet so everyone is just guessing
 
I found adding a choke on one of the DC lines made a huge difference in hum on my lathe treadmill motor. I didn't realise what it was for until someone suggested adding it and I was glad I kept it on the shelf. I didn't have one for my second conversion (drill press) and it hums pretty loudly, so I ordered another choke off ebay for $14. I'll see if it makes a difference on this set up. Worth thinking about.
 
Heres the pics, armature and field leads color codes so I can keep track of them connecting to the controller. All connections are as per Minarik install instructions.

I backed off the IR Comp and that got rid of the oscillation/pulse. I did notice that when the speed pot is turned all the way down but current still going through the hum is barley audible, I have to get my ear next to the motor to hear it. Also, if I back off the pot from full run in somewhat rapid steps the hum stops for just an instant as the speed decreases at each step, then starts again. Maybe its OK, as stated before I don't know how loud a hum to expect, the smell seems to have lessened but still there. Again, as posted above from the site:

The sound that is heard is the magnetic fields energizing and breaking down inside the motor at 120Hz. Although this is normal, a PWM type drive is a good choice if the hum is not acceptable in the application.

The hum is acceptable, perhaps the smell is dust in the motor burning off from sitting for 2yrs......

thanks, Brian


IMG_9042_zpscwnb3erm.jpg

IMG_9048_zpsfayuu3xu.jpg
 
what do the tags say on the 2 brown wires?
 
with min pot at 0 and control knob at 0 hum should go away
 
is the speed control rated for the motor amperage...it is a small controller
 
mattthemuppet said:
I found adding a choke on one of the DC lines made a huge difference in hum on my lathe treadmill motor. I didn't realise what it was for until someone suggested adding it and I was glad I kept it on the shelf. I didn't have one for my second conversion (drill press) and it hums pretty loudly, so I ordered another choke off ebay for $14. I'll see if it makes a difference on this set up. Worth thinking about.
Click to expand...

Didn't know what a choke is, looked at wiki:

In electronics, a choke is an inductor used to block higher-frequency alternating current(AC) in an electrical circuit, while passing lower-frequency or direct current (DC). A choke usually consists of a coil of insulated wire often wound on a magnetic core, although some consist of a donut-shaped "bead" of ferrite material strung on a wire. The choke's impedance increases with frequency. Its low electrical resistance passes both AC and DC with little power loss, but it can limit the amount of AC due to its reactance.

How do I size/select a choke?

thanks, Brian
 
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