Robert J. Lawrie

Robert J.
Preventive Maintenance for Motor Survival
An effective motor maintenance program boosts productivity, reduces unnecessary downtime, maximizes motor efficiency, and saves dollars.
Can four 5kVA buck-boost transformers supply a 20kVA load?
Q Can I connect four 5kVA buck-boost transformers in parallel to supply a 20kVA load? - L.J.F.A Four 5kVA buck-boost transformers can be connected in
Wound-Rotor Motors — High Torque and Adjustable Speed 1
Wound-rotor motors deliver speed control of heavy and high-torque loads.
Does the NEC Limit a Flexible Metal Conduit Run? 5
Q. Can someone tell me if the National Electrical Code (NEC) limits running flexible metal conduit to any particular length? I ask this because I understand
Does Your Motor Have Enough Get-Up-And-Go?
Watch out for energy-efficient motors with insufficient torque to start some loads.
How Dangerous is This Situation?
Q.The electrical system of my Victorian Queen Anne-style home (circa 1900) consists of a mixture of knob and tube, cotton-covered braid, nonmetallic,
Matching Motor Torque To Your Load
You must consider steady-state, acceleration, and starting torque to ensure the lowest motor operating costs.
Can Someone Refresh my Memory?
One of my electricians asked if it was a Code violation to install a 200A-rated, 42-circuit-load center, main lugs only, with protection consisting of a 100A switch/circuit breaker.
More on Why Main Fuses Blow Before Branch Fuses
Why does a main fuse blow instead of the 15A or 20A branch fuse? After checking every branch circuit in the panel with a multimeter, I find no problem.
Selecting Torque for Top Motor Efficiency
Sure, horsepower is an important motor parameter. However, torque is just as important. That said, what exactly is torque? It really depends on your point
Why Does the Main Fuse Blow and Not a Lower-Amp Fuse? 1
Q. I’ve often been perplexed on trouble calls when I find a main fuse blown instead of a 15A or 20A fuse, and I find nothing wrong. I check every branch
Who’s Right?
Q. At my facility, we have several 4160V asynchronous motor applications. A situation arose where a grinding line would blow fuses when anyone tried to
NFPA 70B-1998: Update Takes Shape
The new edition of this electrical equipment maintenance standard includes major changes/additions, mostly on power quality and electronic equipment.
What’s the Most Cost-Effective Way to Obtain 380V? 2
Q. A large textile plant purchased several looms from Europe, which operate on 380V, 3-phase. The only distribution voltage available is 480V, 3-phase.
How Can We Stop This Buzzing?
We recently installed a new air compressor at our facility (LeROI Dressor Model A782287 air compressor with a 20-hp, 208V, 3-phase and magnetic starter)...
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