Infrared scanning of equipment


Thread Starter

Stephen Wright

I recently used an infrared scanning service to monitor the electrical panels in our plant to provide some preventative maintenance information. The scan revealed one switch that was in need of immediate service. When I contacted the manufacturer of the switchgear for information he stated in as many words that infrared scanning was a waste of money. Since electrical switchgear failures were unpredictable the equipment should be used to failure and
periodic maintenance done without scanning. I find it difficult to agree with that position. Has anyone else established a successful program that includes infrared scanning and how have you used the information provided?

Anthony Kerstens

First, in talking to the manufacturer of the switchgear, is this the opinion of one guy, or is it the company line?

Second, I also disagree. An infrared scan will tell you where hotspots are without having to touch HV equipment. Our local electrical power supplier does regular scans of the 27.6KV lines and on one occasion noticed a problem in progress with our line. We also have a guy selling us on scanning inside all our control panels. I'm
giving serious consideration on whether to have him do it, or just buy a camera and institute it as regular PM.

In the end, it is information. The waste of money is what you have to do when you don't have sufficient information.

Anthony Kerstens P.Eng.

Hunter Farris

We established a program at a Chemical plant using infrared scanning. You can definitely see the benifits if you stick with it for a while. The equipment was scanned on an annual basis with the more critical equipment scanned semi-annually. As the program developed, the number of problems discovered each scan decreased revealing that the maintenance work being done was definitely improving the overall condition of our electrical system. I have had the same problems with some of the manufacturers. Most
likely they are trying to keep you buying replacement parts. I know that we were able to prevent several serious failures of electrical equipment. You will not stop all due to the fact that electrical problems can develop quick. However, almost all electrical problems will show signs that can be detected using an infrared camera. The interval of your scans will
determine how many you catch in time. Find a good economical balance between technician time spent scanning and the resulting downtime of the
problems not caught.

Hunter Farris
Each year we have someone come in and scan our MCC's and power vaults. We have been able to advert some real power failures had this not been
done. In my opinion when there is excess heat in switch gear that tells that there is a pending problem.

Ric Larson
Automation Specialist
WestFarm Foods, Seattle WA
For the last 5 years I have been working in a large pharmeceutical plant in Israel. We scan all our switchboards and "heavy" equipment twice a year before our planned shutdowns.

We have saved a lot of time,trouble and money by finding "hot spots" before they cause problems.

I highly recommend scanning.

Steve Zabow

Stairs, David

I agree with Anthony, infrared is a valuable tool in the PM arsenal. In one of my former lives, the insurance company requires us to yearly performed ir inspection and to submit reports showing the
action taken to repair the problem. This was in a particle board plant where the basic ingredient was sawdust, so you can appreciate the danger from hot spots to cause a fire or explosion.

Now in my present life, I'm getting quotes on yearly inspection. Something I've learned from this, perform your inspections while the equipment is loaded and have the person who will make the repairs aid the person inspecting.

David Stairs
Process Engineer
Omstead Foods Limited

Pierre Desrochers

Stephen Wright wrote :
. Has anyone else established a successful
> program that includes infrared scanning and how have you used the
> information provided?

Just to add a little point of view.

10 years ago I started to have some IR scanning equipment service center come in a plant wich I managed and the following occured.

First we add our electrician open ALL the cabinet doors during the night before the inspection.

Then the technician would do a walk through with another electrician. He would scan ALL circuit and print us picture of the hot spots. We fixed them all but ...

Talking to him we experience scanning of motors, gearbox and before you know it we where scanning cable trays, screw conveyor, belts, high voltage lines ... and fuses...

I was amazed at what this instrument could pickup. We where able to see loose screws holding cable trays 30 feet up. Bushing going awol. Screw conveyor's fins scraching the inner surface of the conveyor. Even security fences and water pumps having loose brackets...

The cost of having him come in for 1 or 2 days was nothing compare to the information we got back. We would do it 3 months before the annual shutdown and it gave us the time to plan some repair with long delivry time...

Its so easy and so clear ... a picture is worth ... well you know ...

Pierre Desrochers
Integral Instrumentation Inc.

Darold Woodward

"Scanning" as you have called it or thermal imaging using Infra-red for looking at electrical equipment has its origins in the utility industry. It is not easy to "see" current flowing in a device and understand if it is hotter than it should be without this technique. It has some value, but it is limited. As part of a comprehensive maintenance and testing plan it is probably a useful tool.

I certianly don't agree with the "use to failure" philosophy. Certianly a $10 annual test for a $5 - 120V, 20A circuit breaker would be a bit silly. I don't think that this guy ever had to answer to production people who expected the
plant to be running 24/7 either. Maybe he used to work for a now famous and defunct switchgear manufacturer whose gear operated until failure because circuit breakers failed to operate properly. On the other hand, not all failures can be detected before they happen so there is no substitute for proper design and reasonable redundancy.

Probably just as important or more important than observing the temperatures on any given day is collecting a baseline reading and comparing to future readings. This will give you an idea of deterioration of a device.

Scanning might be an interesting technology to use to see if there is unexpected heating on cables, conductors, neutral busses, etc. due to harmonics or other harmful conditions that might not cause a circuit to trip.

Here are some examples of its limits:

Scanning does not tell you if a circuit breaker trip mechanism is going to operate correctly. I have seen several cases where testing has revealed failed trip mechanisms. If circuit breakers are all ready to trip properly (and set
properly), damage from failures will be minimized.

While using this technique in a vault may tell you if a splice was made correctly or is overheating (or a cable is overheating), it does not tell you the insulation or jacket material condition. An insulation failure could be just as disasterous as a overheating.

Contact wear, pitting, and misalignment on large devices may or may not be revealed by this type of testing because they primarily affect the gear during connection or interruption of loads.

I haven't seen any articles recently, but you may find some interesting information on this in the trade journal EC&M (Electrical Construction and
Maintenance). They have excellent coverage of plant electrical system maintenance and design issues.

Darold Woodward PE
Schweitzer Engineering Laboratories
[email protected]