Troubleshooting In The Field - Motor Testing - Motor Controller - Programmable Logic Controllers (PLC)

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 skills in troubleshooting.

On the job, training on PLC 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.          

Basic troubleshooting techniques apply to every situation and occupation. Positive identification of the problem 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 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.