NEMA23 steppers getting very hot

[Angelos]

Hello All,
I am an electronics engineer but new to CNC milling. I have uses small steppers before (salvaged from ancient hard drives and floppies) but never used anything large.

Yesterday I received three NEMA23 size steppers which I ordered for my new milling machine. These are Mclennan 23HSX-206 (datasheet here: http://www.mclennan.co.uk/datasheets...per_motors.pdf )

I run them last night from my lab PSU at 32V with a Geckodrive G210 limiting the current to about 1.2A. When not in motion each motor consumed 320mA. To my surprise the motors became very hot. So hot that it is not comfortable to touch them. I couldn’t hold them tight in my hand for over 10-15 seconds or so.

At the moment I run the motors in parallel winding bipolar configuration. However the heat was similar even when I was using only two windings and leaving the other two unconnected.

I would appreciate your thoughts please. Are they meant to run so hot?

Many thanks,
Angelos

[pack rat]

MY toughts from reading in this forum, stepper motors are design to run hotter then normal motors, especially in holding pattern where they are not moving. Also the faceplate in contact with aluminium support helps in getting rid of hear. I read that extreme cases people put a fan and blow at the motor. If I recall correctly max safe operating temperature is 200F.

[vladdy]

Hold current on cheap [inexpensive] controllers is usually FULL current, pop in a couple of high power [10w] oh around maybe 7.5 to 15 ohm resistors, or spring for a controller that supports reduced hold cuurent capabilty..should be able to handle them at working temperature..

[HuFlungDung]

Angelos,

Some of the guys here joke that "It's not hot til you touch it", so hands off

[limbo]

These steppers have very low coil resistance (0.7 Ohm) and low inductance. When you run them from a chopper drive with high supply voltage the iron losses increase dramaticly. Some people use as rule of thumb that the chopper supply voltage should not exceed 6-10 times the DC rating of the stepper.

From your datasheet it looks like this DC voltage is roughly 1.5V, so if you lower your voltage to something like 15V they should stay a lot cooler. Then you can safely increase the current to the max. allowed by the datasheet, giving full torque. The low inductance in these steppers will give good speed even at relatively low voltage.

John