Easier Than A, B, C
Tip written by: Infraspection Institute
When performing infrared inspections of electrical distribution systems, many people identify the individual phases of polyphase circuits as A, B, and C; others frequently use 1, 2, and 3.
Confusion can arise with alphabetical or numerical labels particularly when switchgear enclosures are inspected from different perspectives e.g. front versus rear. Further confusion can occur when phase rotation has been modified or changed or, in some cases, mislabelled.
Reference errors can be avoided by using terms that cannot be confused such as Left, Middle, Right OR Upper, Middle, Lower. When using such terms, one should always reference where the image was taken from. For outside power lines references such as Street, Center, and Field may be used to identify phases without confusion.
Using the above simple terms can make your reports easier to understand and help to eliminate confusion when repairs are performed.
Infrared inspection of electrical distribution systems is one of the many applications covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
Tip written by: Infraspection Institute
Emissivity refers to an object’s ability to radiate infrared energy. Because infrared instruments measure radiant energy, it is imperative for a thermographer to understand emissivity and how it can vary.
All objects above 0 Kelvin radiate infrared energy. The amount of energy radiated is dependent upon an object’s temperature and emittance. Increases in temperature and/or emittance will increase the amount of infrared energy radiated.
Although many equate emissivity to values published in emittance tables, emissivity is a dynamic characteristic and is influenced by several factors. Among these are:
Wavelength – For most objects, emissivity varies with wavelength.
Object Temperature – Changes in object temperature cause changes in Emissivity
For clean metals, E increases with temperature rise
For dielectrics, E decreases with temperature rise
Viewing Angle – Imaging at angles other than perpendicular causes changes in Emissivity
Target Geometry – Target shape affects Emissivity. Compared to a flat surface,
Concave shape increases E
Convex shape decreases E
Surface Condition – Surface roughness, texture, or condition (dirt, oxidation or paint) can significantly affect Emissivity
Although thermographers frequently obtain emittance values from published tables, this practice can introduce significant temperature measurement errors since emittance tables cannot account for several of the above factors. Because of this, calculating emittance with one’s thermal imager will help to ensure measurement accuracy.
A simple procedure for calculating emittance may be found in the Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers. To order a copy of this or other standards, call Infraspection Institute at 609-239-4788 or visit the Infraspection Online Store.
Careful Testimony at Your Fingertips
Tip provided by: Robert J. Incollingo
Attorney at Law
When called on to answer a question under oath, put your left hand on your lap, fingertips to your pant leg and think about the tip of your thumb. Your thumb reminds you that you have a predicate question of your own to answer for yourself, before you can even begin to reply to the other person. Counting on your thumb reminds you to ask yourself first, “Did I hear the whole question?” There are lots of reasons why you might not hear a question; your mind wanders, someone in the room speaks or coughs on top of the question, you don’t hear so well, outside traffic noise spikes, a distractingly pretty girl wanders past, or the inquirer mumbles in a heavy accent while covering his mouth with his hand. Maybe you were thinking of your thumb. If you didn’t hear the whole question, you cannot answer but to reply, “I didn’t hear the question. Could you please repeat it?”
If you did hear the question, your index finger should twitch. Your index finger is trying to remind you to ask yourself, “Did I understand the question?” There are lots of reasons why you might not understand a question; you don’t know a word, a word you know is being used in an unknown context, the question assumes a fact which is not true or not in evidence (of the “when did you stop beating your wife” variety), or the question is a leading question that incorporates a statement which it asks you to admit or deny, and as phrased you can do neither (such as, “You were wearing pants this morning when you hit my client, weren’t you?”). Sometimes, the question isn’t even a question, but a form of copspeak, a statement coupled with a pregnant pause. (Here your lawyer should jump in and state loudly for your benefit, “Objection as to form. No question pending.”) We must also admit the possibility that you are a dullard, the question is beyond you, and this whole business of questions reminds you unpleasantly of school.
If you didn’t truly understand the whole question, you must sensibly ask the questioner, “I didn’t understand the question. Could you please rephrase it?” Be prepared to get another question in return, “What part didn’t you understand?” Look blank for a meaningful second, and reply, “I’m not sure. If you rephrase it maybe I can answer.”
If you heard and understood the question, your middle fingertip will press against your leg, insistent that you ask yourself, “Do I know the answer? If not, is it because I don’t know the answer, or because I forget the answer?” This distinction makes much more of a difference on the stand than in regular life. If you knew something but forgot it, your recollection can be refreshed and introduced into evidence. If you never knew it, your testimony is not competent on this point, and is thus worthless forever. Sorry.
Should you reply, “I don’t know,” expect the follow-up question, “Well, who would know?” Look blank, and start on your thumb again. If you know who would know, say so and stop talking. Otherwise, feel free to say you don’t know who would know. They can’t mess with you this way.
Should you reply, “I don’t remember,” expect the follow up question, “Can you think of any documents which would tend to refresh your recollection?” Look blank, and start on your thumb again. And so on.
If you know the answer, your ring finger will tap and twitch to tell you that you are in the greatest danger of all. The pressure of your ring fingertip against your leg reminds you that you must answer the question truthfully in a manner that is only apparently helpful, and then stop talking. Answer only the question asked, which you are now presumed to have heard and understood, and coming to the very first period at the end of the very first sentence of your answer, stop talking. Stop talking. STOP TALKING. Do not answer the question you believe should have been asked; do not tell the questioner what you think she needs to know; do not answer a question with a question; do not object, or protest to your lawyer or the judge, “Do I have to answer that?”; do not preface your answer with an aside such as, “Can we go off the record for a minute here?” Instead, respond only to the question asked, as briefly and as generally as you can get away with, without obstructing justice. Do not blather, do not be helpful to the questioner, do not be funny, do not let your temper run away with you, do not lie. Answer in as few words as possible and then, you guessed it, stop talking.
And your little finger? Well, your little finger goes, “wee, wee, wee” all the way home. We thought you knew that.
Robert J. Incollingo, Esquire
1010 Kings Highway South – Building One Floor 1
Cherry Hill, NJ 08034
Bob Incollingo is an attorney in private practice in New Jersey and a regular speaker at Infraspection Institute’s annual IR/INFO Conference.