The recommended minimum insulation resistance to ground when measured at, or corrected to, 40 degrees C, is the reated machine voltage potential in kilovolts +1, in meg ohms. Unit should be meggered 1 – 10 minutes for a polarization index value. 2.0 is considered a minimum value when you divide the 10 minute reading by the 1 minute reading. The PI value is the result of that division.

Yes, but it is usually not cost efficient.

Yes, our automation and controls division can evaluate what your needs are and will customize a design, fabricate the enclosures and controls and program the system to your needs. We will then provide CAD drawings for future reference.

Yes, we have portable meggers, surge testers, and DC absorption equipment that can be used in the field.

We are available 24 hours per day; 7 days a week to provide sales or services to keep your business running. Our regular business hours are Monday through Friday, 8:00 am to 4:30 pm. Our after hours “Emergency” phone number is 314-638-0166.

Our Crane and Hoist division has certified technicians to provide monthly, quarterly or annual inspections. We will tag all of the equipment inspected and give a written report on each piece, with a quotation for repairing or replacing any unsafe equipment.


Click Here to review the federal OSHA crane regulations (standard-29 CFR ).

Yes, Zeller Electric entered the U/L program at its very beginning in 1977.

We service both types with limitations. The majority of the servo motors are imported. They come with many types of speed and control regulators such as encoders, TAC generators and resolvers. When we receive units that we cannot connect to our control stations to completely test, we will send them to a qualified station that can give reliable service on that particular unit.

Depending on the size of the bearings, RPM, the number of hours running, if the motor is vertically or horizontally mounted, or in a hostile environment will all affect the frequency of greasing. A motor should be greased according to the manufacturer's recommendation. A simplified chart is available that we can send you.

No, there are twelve(12) different types of lubricant compounds. The chances are that they will not be compatible.

This would depend on the type of application, bearing type, size of the bearing and bearing housing, and type of cage on the bearing. The amount of grease and the correct procedure should be as the manufacturer recommends. We can send you a simplified chart if you would like.

Yes, we perform a service called ‘PMP’ (Predictive Maintenance Program). This service is performed with equipment running in normal state with no shutdown required. Frequency of testing depends on how critical the equipment is for plant operation. The cost of testing is based on the number of pieces and points that need to be checked. Call for a FREE ‘on site’ appraisal.