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Industrial Troubleshooting - Electrical

By Larry Bush

electrical industrial troubleshooting

troubleshooting in the field - motor testing  - motor controller - programmable logic controllers (plc)


within the industrial troubleshooting realm today, electrical troubleshooting also requires great computer skills. a laptop computer with plc programming, communication, and operating programs are a necessary tool in today's modern plant. engineers, production supervisors, maintenance supervisors, maintenance technicians, electricians, instrument technicians, and maintenance mechanics all need to have plc and computer knowledge, training and troubleshooting skills. more about plcs towards the end of this article.


basic troubleshooting techniques apply to every situation and occupation. positive identification of the problem(s) is absolutely essential to solving the problems. many times, the inexperienced troubleshooter will mistake one or more of the symptoms for the problems. solving the symptom(s) will normally just postpone the problems to a later date. by which time, the problems may have grown to mountainous proportions.


an example is when a person experiences a headache and takes a mild pain reliever, such as aspirin. the actual problem might be any number of things: eyes need to be checked, medication or lack of medication, muscle strain, stress, tumor, blood vessel blockage, or old war injury. the same thing occurs in industry, a fuse in a circuit blows and the maintenance person gets the replacement fuse and inserts it into the fuse holder. there are many things that could have caused the fuse to blow, depending on the complexity of the circuit.


excess current caused the fuse to open (blow). excess current could have been caused by: overload on the load; short circuit between the wires, grounded wires, short circuit in the load, ground in the load, voltage spike, voltage droop, etc. if the maintenance person does not troubleshoot the circuit prior to replacing the fuse and restoring power, negative consequences could arise.


it is not uncommon for a process to develop a number of small problems and continue to function at a degraded level of operational capability. then, one more small problem occurs and the whole process breaks down. finding and correcting the last problem will not necessarily restore the operational capability of the process. the process continued operations with the small problems, but the small problems may not allow the process to restart from a dead stop. all the other small problems must be identified and corrected before the process is restored to full operational capability.


this situation arises in industry as well as a person. the person can continue to function with a number of small problems, such as fatigue, blood pressure problems, hardening of the arteries, artery blockage, but one more small blood clot in the wrong place could easily cause the death of the person. clearing the blood clot does no good to the person. they will not be restored to full operational capability.


field electrical troubleshooting:


unless prior experience dictates otherwise, always begin at the beginning.


ask questions of the operator of the faulty equipment:



tip: add this electrical motor troubleshooting chart url to your favorites so you can call up on your smart phone to guide you during electrical motor troubleshooting.


check controlling sensors in area of problem, then make complete check of all sensors, limit switches and other switches to ensure they are in correct position, have power, are programmed, set, and are functioning correctly.

if and when a problem is found, whether electrical or mechanical, the problem should be corrected and the fault-finding begun anew, a seemingly unrelated fault or defect could be the cause of the problem.


when there is more than one fault, the troubleshooting is exponentially more difficult, do not assume that all problems are solved after completing one, always test the circuit and operation prior to returning the equipment to service.

if available, check wiring diagrams and plc programs to isolate problem.


variable frequency drive (vfd) can be reset by turning power off, wait till screen is blank and restore power; on some vfd's, press stop/reset - then press start.


check that wiring is complete and that wires and connections are tight with no copper strands crossing from one terminal to another or to ground.


ensure that the neutral reading is good and that the neutral is complete and not open.


electric motor testing in shop:


prior to connecting a motor:



electric motor testing in field:


when a motor overload or circuit breaker trips and/or blows fuses, certain procedures and tests should be carried out:



motor controller:



pc plc training:


on the job training on plc's is usually not very effective until the person being trained has reached a certain level of expertise in several areas. knowledge and skills in electricity, troubleshooting, and computer operation are necessary prerequisites to effectively assimilate basic plc training. the author found that long term retention of material studied was higher from a vocational course taken at a local junior college than from a fast-paced, cram-course through a manufacturer.


the manufacturer's course covered essentially the same material as a course at the junior college (jc). the major differences were the amount of study time and shop time. the jc course was four hours of class time per week for 15 weeks. there were three hours of shop time doing actual hands on work of the problems and material covered in the first hour. additional time was spent at home studying the manual and writing programs. also, the jc was open at night for extra shop time on the plc's and computers.


in contrast, the manufacturer's course was five, eight hour days. class work was extremely fast and condensed in order to cover the amount of material involved. the instructor was very knowledgeable and covered the course material as we tried to input the programs into desktop training equipment in order to see how it worked. by the end of each day, our minds were jammed with information. by the end of the week, we all passed the course, but i had a hard time remembering what we had studied on the first day.


programmable logic controllers (plc):



about the author: larry bush has been an electrician for 47 years, and in maintenance management for 22 years. download his e-books "maintenance policy and procedures manual" or "emergency diesel electric generators ebook" !


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