Jeff Knight

Starting and sustaining a motor reliability program is a real challenge. Even smaller condition based maintenance (CBM) projects can be very difficult to sustain over time. We have had the opportunity to work with many maintenance and reliability professionals who have successfully faced this challenge, and this new series will promote some of those lessons…

This past year we had the pleasure of interviewing some very distinguished maintenance and reliability professionals working with our local industry. We talked about the mission of maintenance and the goals of manufacturing. We talked about the challenges of staffing, training, budgets, and even plant politics. The feedback we received helped us plan for investment,…

Electrical testing of motors can be very complicated, yet its importance is often under-estimated.  One of the most basic tests is the insulation resistance test, also referred to as the Megger test (due to the powerful Megger brand name). Though basic by nature Megger tests are very useful. However, if proper guidelines are not followed the results can be suspect.…

Motor rotor balancing can be a confusing topic leading to sometimes heated conversation, especially in motor shops where cultures have evolved so differently over the years. All rotors must be balanced, whether new from the factory OEM or recently repaired. But the methods of balancing vary, as does the quality of the work. In this post…

A thermal audit of electrical enclosures can be revealing. Statistically three out of ten enclosures are too hot for the power electronics and controls inside them. But this can be easily remedied with the addition of thermal cooling systems. The trick is identifying your problem areas quickly and efficiently, which brings us to the thermal…

  On average 3 out of 10 enclosures require thermal cooling.  Why be concerned with thermal management of electrical enclosures? Based on statistics, 30% of operating systems are being heat stressed, resulting in poor performance, premature failure, and erratic operation. Nuisance drive tripping often comes to mind when thinking about enclosure heat, but the problem…

A severe duty motor, in short, is an improvement over a standard totally enclosed fan cooled (TEFC) motor. They are tougher and better suited to an industrial environment. There is no standard specification on what a severe duty motor is, so designs vary. They could be viewed as a step between a full IEEE 841…

Why be concerned about high speed VFD fuses? A few weeks ago I was walking through one of our warehouses and noticed a stack of variable frequency drives (VFDs) awaiting repair. You may be aware that we offer repair services for industrial electronics, and so it is common to see I/O boards, instruments, and drives going out…

Insulating Motor Connections For Reliability It’s the simple things that we seem to take for granted in an industry where so much experience is retiring away. How do you properly tape a motor lead connection? What type of tape do you use for a connection, and how many layers? We see lots of motor connections…

Motor connections that keep you running – Low Voltage Applications A proper motor connection is a fundamental and often overlooked component to a reliable motor circuit. Unfortunately, our test teams and repair shops continue to find problems with high resistance and grounded connections resulting from: Vibration Heat Moisture Contaminants Improper handing Compression in Jbox (too…

Short circuit protection for VFDs – is recommended branch circuit protection enough? As noted in a recent post, many drive manufacturers have removed semiconductor fuses from VFDs and provide protection guidelines per UL standards. There are multiple levels of short circuit testing and protection; and the manufacturer makes that choice. The question is could you…

  The benefits of the right line reactor – for drives and motors. A line reactor can enhance performance, life expectancy and efficiency for motors and drives. Line reactors serve as a current limiting device for harmonic and transient waveforms, and can make a tremendous impact. Nuisance tripping, heat, noise, and premature failure are a…

Don’t Get Caught Without High Speed Fusing Over the years major manufacturers have removed internal semiconductor fuses to cut costs. Most are recommending standard circuit breakers or fuses recommended by NEC for protection, again to minimize installed costs. While this will protect the circuit and the motor, the internal components of the VFD are unprotected.…