dear all,

i'm doing a research on IRT, comparing thermal images. i have design a simulation equipment which consist 5 common faults in electrical namely as loose connection, overload, phase reverse,phase loss and under voltage. Once i get the image for each fault i tried to compared. The problem is the images seem looks the same so i make a conclusion that by using IRT we still cannot define what is exactly and actually the Hot Spot can tell us. Is anyone here disagree with this opinion?

If the connection is bad enough, it will show up differently.

As you increase load on the circuit, temperature rise above ambient should increase. A very rough correlation is that temperature rise is proportional to current to the power 1.6 assuming nothing else changes.

Loss of a phase would normally show up as a cooler phase unless the other phases are already at very load load.

The effect of low voltage on connections is generally not directly observable unless it changes the circuit current.

Phase reverse and under voltage, would not be possible as they will not produce an anomally from a thermal point of view.

The most common problems I find are:

High electrical resistance
Inductive load
Open circuits
Energised ground cables
Short circuits
Motor problems

The effect of low voltage is unlikely to be detected with IR as Electricpete says, unless it is extremely low and leads to an increase in the current.

There may be something wrong with your simulation as you should easily detect the loose connection.

What camera are you using?
What training have you had?
What is your background?
How does you your simulation equipment work?

thank you guys for the answer. at least i have something to present on my next review project session. i will take note all your comment!! Actually all of that 'common faults" just happened inside my premise and not to point to outside or globally.

to mr. bob berry;

1. i am using ThermaCam SC2000.
2.Level II
3. what do you mean by "my background??" is it so relevan with this portal, well should be no problem to answer, BSc. Physics Electronic and undergo MEng (Microelectronic)..
4. The simulation is in good condition but as i said, they were not diferrent from each other (just like what u both said)..

continue..

i manage to 'catch' the loose connection image..
Anyway, do we have any standard reference for IR procedure. To be more specific, let say we found a hot spot (not a reflection or whatever), how do we know that hot spot is 'a problem", if it is 'a problem', how did u determine that, based on what??

What is the material of the connection where the hotspot occurs? What is its maximum operating temperature? Will the hotspot cause stress concentration or even melting?

I haven't seen any thermography standard for industrial use. The nearest is one by Infraspection Institute.

Pepcz:
Correct me if I am wrong, but are you purposefully excluding other data sources for acedemic purposes?

Whether or not it is a problem DEPENDS. I never make a call based only on Therm data. I collect Wire gauges, ambient temp, loads, voltage drops across all three legs, Comparable device data (if available) and then sort it through a criticality decision sequence.

You can also use other technologies sometimes, ultrasonic, vibration etc...

Is this an acedemic exercise or practical?

Moore,
Tq for those suggestion and explanation. Actually i do both.. as a researcher to have more relevan data/facts to explain/present is better..

Pepcz,

I do feel strongly that both procedures and severity criteria should be developed on a site specific basis and if this is what you are trying to do then you might be trying to re invent the wheel a bit. I know people in your industry (Nulear) that use guidelines and severity criteria developed by EPRI. There are of course other sources of information, ie. NAVY, NETA and NMAC are the most common. While I dont really agree that these are appropriate to every facility, they do provide a good starting point when developing your own criteria and procedures. If you develop your own you should consider them a live document that will change and adapt as your program develops.

what about Phase reverse? Why it is not possible for IR to detect this fault?? Any explanation?

Phase reverse will not produce an anomally because it does not effect the heating on the phases. I have never seen phase reverse having any effect on the amps running through the phases and if there is no difference in the load then there will be NO thermal difference. While phase reverse does cause problems, mainly motors running backwards, this will not effect the patterns we see on contactors, starters and isolators. It might produce a thermal difference on the motor though, but it should be pretty easy to tell if a motor is running in the right direction without thermography.