425oz motor runs hot

[carvemylog]

I have a Kehling KL23H286 425oz motor on my Z axis and KL23H276 282oz motors on my X and Y axes, KL5056 drivers, and the 48V, 12.5A PS. I've wired the motors in parallel. The specs indicate the 425oz motor is 2.8A in parallel, and the 282oz motors are 4.2A. I set the current limits on the drivers for 2.7A on the 425oz motor and 3.8A on the X and Y.

When running the machine or when not stepping but with the power on, the 282oz motors only get warm to the touch, but the 425oz motor is getting extremely hot. I tried turning the current on the 425oz motor to 1.4A (as low as the 5056 will go) and it doesn't seem to make a difference. I know steppers can run hot and I'm going to borrow a thermocouple from work to see hot hot it is gettting, but I'm not sure why this motor would be running so much hotter then the others, especially when my X motor is spinning alot more.

Any ideas? Thanks.

[jalessi]

Have you enabled the current reduction on the drives, I believe SW4 controls the current reduction.

[carvemylog]

I didn't see anything in the pdf manual that described what SW4 did. I left all the drivers' SW4 swtiches in the "1" position. Is this the idle current reduction, meaning it reduces the the current when the motor is not moving?

[jalessi]

Try turning SW4 off for current reduction.

The instructions for current reduction out of the factory manual is as follows:

Standstill current setting SW4 is used for this purpose.
OFF meaning that the standstill current is set to be half of the selected
dynamic current, and ON meaning that standstill current is set to be the same as the selected dynamic current.
The current automatically reduced to 60% of the selected dynamic current one second after the last pulse. Theoretically, this will reduce motor heating to 36% (due to P=I2*R) of the original value.

[LeeWay]

When I converted my little lathe, i used 270 oz motors with G201's. They don't have current reduction. My motors would get pretty warm, but one would get hot. Not too hot, but you could feel the difference between them. That particular motor was powering the tailstock. I just thought that was odd that 3 identical motors, drives, wiring, PS etc yields different temps on the motors regardless of usage.
Okay, now I'm done not helping.

[carvemylog]

Try turning SW4 off for current reduction.

The instructions for current reduction out of the factory manual is as follows:

Standstill current setting SW4 is used for this purpose.
OFF meaning that the standstill current is set to be half of the selected
dynamic current, and ON meaning that standstill current is set to be the same as the selected dynamic current.
The current automatically reduced to 60% of the selected dynamic current one second after the last pulse. Theoretically, this will reduce motor heating to 36% (due to P=I2*R) of the original value.

Thanks, I turned SW4 off on my 425oz Zmotor and it made a huge difference. It now runs at about the same temperature as the other motors do with SW4 on (pretty warm to the touch but not painful to hold) Not sure why there's a difference, but it's working I'm not gping to worry about it.