Electrical preventive maintenance


Thread Starter


Hey Guys,

I'm responsible for electrical maintenace in our plant where we use hundreds of servo motors and ethernetIP communication, now our challenge to minimize the down time, so I'm woundering guys what kind of electrical preventive maintence we have to make in our plant to increase the uptime and not fire fight with the machines. Just to let you know that we do termination and vibration analysis, we have got the infrared camera to use for the hot spots, my question to you guys beside that, what we have to do? in terms of motion what we can to do to the drives, because from time time we do change some electrical drives, and what about the servo motors and other this... any suggestions?

thanks in advance,

Curt Wuollet

Connectors and connections!
It has been estimated that 80% of machine problems are related to bad connections and connectors. When you attend to a piece of gear, at the very least, inspect the connectors and terminals. Unless you are in a really filthy environment, cycling pressure connectors and tightening terminal strips will produce a noticeable decrease in problems. To this end, using spring loaded connectors such as the wago or beckhoff type in vibration environments will also show an improvement. It's hard to stress this enough until people keep track of how many problems are fixed by cleaning and tightening connections, perhaps after replacing components damaged by heating connections or arcing, etc. In really bad environments, this can sometimes contaminate a good connection, but it's a good practice in nearly all cases.

Compile detailed failure information, including repair reports from the servo manufacturer, or independent repair depot, and internal data such as machine symptoms, troubleshooting steps, and related or concurrent failures (i.e. - failing bearings in the driven equipment, equipment soaking due to a burst water hose, etc.).

Maintaining a thorough machine history is difficult to pull off, but well worth the effort. It should become a storehouse for looking up past failures (and their resolutions), and an aid for divining failure root causes, and thus suggesting courses of action towards maintenance improvement.

Modern servo drives tend to have sufficient parameters for setting current limit, and the like - so long as those values are selected appropriately then the opportunity for winding burn-out is minimized. If failure reports indicate toasted windings then re-visit those parameters, and, in general, the overall application, and ambient conditions..

If there are a lot of encoder failures then endeavor to learn the failure mechanism - typically excessive vibration (especially when glass disk encoders are used), and, in my experience, cable failure (when the motor is on a movable platen, and wiring/connector system is subject to flexture), and excessive temperature.

Servo motors are often rated for two or three operating profiles - convection cooled, forced air cooled, and (if the motor supports it) liquid
cooled, and each of these profiles allow increasing power levels. If the motion axis was designed for forced air cooling, and the motor operates near the edge of the performance envelope, then cooling fan maintenance becomes
paramount. Dirt build-up in the cooling shroud and motor radiative surfaces decreases cooling efficiency, and (if dirt builds up enough to stall the fan blades) eliminates forced cooling altogether. Electronics built into the encoder tends to be the weakest link, and tend go haywire first when subject to high temperature operation.