motor testing

Evaluating Winding Connections With Infrared

Introduction

An area that is often overlooked in the rewinding of an electric motor are the internal connections of the winding. Most coils have multiple wires making up one ‘conductor' (Figure 1). The reason for this is to allow the wire to be more flexible for installation while allowing enough cross section for the amount of current that the conductor must carry. This generates a situation where improper brazing, crimping or other methods of making the connections will generate a hot-spot due to IR losses.

Take the Big Picture Approach

Managing the Complete Motor System

Modern management practices often do not take into account the importance of motor systems maintenance and management requirements. Through efforts in cost control, many industrial and commercial firms reduce maintenance staffs, take least cost approaches to corrective actions and sacrifice preventive maintenance programs. The result has been increased energy costs and downtime resulting from equipment not operating to full potential and failing unexpectedly. The problem results in $100's of billions of dollars in additional energy consumption and lost revenue. Unfortunately, in many cases, the connection between the cause and effect is not made.

Motor Current Analysis (MCA) Test Results Can be Misleading if Drive Train Load Isn’t Considered

By: Jason Bolte, CMRP, Allied Reliability, Inc.

A constant issue when applying Condition Monitoring technologies is buy-in that the technology is capable of detection of failure modes in machinery. It is as critical to ensure that readings are interpreted properly to determine that a fault does not exist as much as that one does. Nothing sabotages buy-in more than the knowledge that repair activity has taken place that was unnecessary. One of the keys to effective data analysis is that we take consistent repeatable data. This is particularly of note when considering motor loading when performing Motor Current Signature Analysis (MCSA) testing.

Managing the Complete Motor System

A Closer Look at Air Gap Eccentricity

by Douglas E. Swinskey & Peter M. Bechard

The first step in evaluating test data is understanding the relationship to the circuit's Fault Zones and how abnormalities in a specific Fault Zone affect the performance of the motor. The six Fault Zones (Power Quality, Power Circuit, Stator, Insulation, Rotor, and Air Gap) are derived from the most common electrically related motor failures in industrial environments. The Air Gap Fault Zone describes the measurable distance between the rotor and stator within the motor. Air gap eccentricity is a condition that occurs when a non-uniformity in the air gap between the rotor and stator exists.