Joe Gierlach, Manager – Technical Training & Support, TEGG Corporation
The IR camera is a great tool used in our everyday predictive maintenance endeavors, but it can play tricks on our eyes if we do not investigate beyond what we are observing. Things truly are not always as they seem, here’s an example:
1) As indicated in the images below, we “appear” to have a hot spot and differential in temperature on the “C” phase of the breaker, just to the bottom of the actuator handle.
2) The operating parameters at the time of this visit were as follows:
Rating
200 amps
Loading
“A” – 8 amps
“B” – 48 amps
“C” – 24 amps
THD%C
“A” – <2%
“B” – <2%
“C” – <2%
Millivolt Drop
“A” – .001
“B” – .001
“C” – .001
Relatively normal operating conditions in a generally climate controlled room, with no evidence of any reflective source of infrared radiation noted.
3) So why is there a temperature of nearly 40° C (104° F for those who relate to Fahrenheit)? With a high emissivity on the breaker itself, reflective effects would need to originate from a much higher heat source to have an effect on the observed actual temperature on the breaker.
4) How could the operating parameters be within guidelines, no apparent resistance increase was measured across the breaker contacts via milli-volt observation, harmonic distortion levels were deemed negligible, and the highest load demand on “B” phase DID NOT have the highest temperature rise?
The answer to this was revealed when the breaker manufacturer, Cutler-Hammer, assisted in the dilemma resolution. The source of the heat was determined to be an under voltage relay coil used in conjunction with the electronic sensing and trip unit, mounted under the case at the location illustrated above. The heat associated with electromagnetic induction properties or transformers and coils radiated to the breaker case and were detected by the IR camera.
The unit in question is illustrated in the blow up view, showing this can be either left or right hand mount.
Below is an assembled view illustrating physical location of where “heat” may be observed.
Another good example is illustrated below. A transformer with balanced loading well below its rating, low harmonic content, and no extreme conditions present in the surrounding environment “appears” to have a coil winding that has a temperature difference of nearly 10° C between “B” and “C” phase windings, as indicated by the arrow. The “B” phase winding was approximately 48° C and the “C” phase was approximately 41° C.
Based on those operating parameters, this is a problem as defined by NETA guidelines that is near the “Severe” range as related to our severity criteria levels. In fact, closer quantitative analysis of the thermogram reveals the reasons for the “apparent” differential temperature.
1) The “B” phase winding does not have the volumetric area to allow for natural convection cooling of the heat, thus it cannot dissipate heat as efficiently.
2) The core temperature is much higher as compared to the windings and the heat generated in this area will influence the winding temperatures if its effects are not compensated for. This causes a radiating of heat to impinge on the winding and affect the observed temperature.
3) The actual measured temperature does not exceed the manufacturer specified guidelines with respect to temperature.
Again this example illustrates the absolute need to provide quantitative analysis of any “apparent” thermal anomalies. Other surrounding factors had an effect on what we were observing and they had to be taken into consideration.
Conclusion
With the advent of solid-state protection in devices of this nature, this scenario is going to become more common. We cannot rely on what we see alone, and sometimes even the analytical tools at our disposal still fail to reveal the source of a problem.
The first example aids in demonstrating the absolute need to utilize milli-volt drop tests with respect to thermal anomalies, as it will provide one of several methods in assisting us to prove or disprove the presence of an actual problem, by effectively measuring and quantifying the passive resistance of a contact point using Ohms law, and allowing us to calculate I^2 R losses. With the lack of voltage drop and harmonic currents in this problem, we can safely determine the breaker contacts and terminations are suitable and heating is not related to non-linear loading.
To rely solely on temperature difference from similar components or ambient air is not enough for us to diagnose a problem such as this. Even the generalized guidelines in the NETA specs for electrical equipment cannot be relied upon as a rigid benchmark in this respect. If the NETA standards were applied in the above example, it would be approaching the “Critical” level, as the temperature difference is compared to ambient is nearly 40° C. Is the case in the first example? Would you recommend an immediate outage to service this component? Not likely with the operating conditions noted. In the second example, the untrained eye would most certainly identify this as a problem based solely on differential temperature guidelines.
We must use all of our tools to draw accurate conclusions, as many factors need to be taken into consideration with respect to these types of situations. We cannot just assume that because a certain temperature differential exists, apparent or true, particularly with respect to direct measurement, that a problem exists. Making qualitative and quantitative analysis is key in keeping us one step above the rest. Sure a hot spot exists in these examples, but your eyes can deceive you if you do not give consideration to such variables as external influencing factors and load demands, and not provide proper compensation values to the IR camera for these factors.
Probably 80% of all testing. performed in electrical power systems is related to the verification of insulation quality. This Cadick Corporation Technical Bulletin briefly describes the fundamental concepts of insulation testing including – insulation behavior, types of tests, and some test procedures. For more detailed information, refer to the bibliography at the end of the paper.
Probably 80% of all testing. performed in electrical power systems is related to the verification of insulation quality. This Cadick Corporation Technical Bulletin briefly describes the fundamental concepts of insulation testing including – insulation behavior, types of tests, and some test procedures. For more detailed information, refer to the bibliography at the end of the paper.
When selecting pressure measurement transmitters, the first stage is whether to opt for a transducer or a transmitter. Although the terms are often confused, there are several differences between transducer and transmitter devices. A transducer creates a low-level electronic signal in response to changes in applied or differential pressure. As with transmitters, transducers feature an internal sensor that converts the applied force into an electrical signal, from which the measurement is derived.
When selecting pressure measurement transmitters, the first stage is whether to opt for a transducer or a transmitter. Although the terms are often confused, there are several differences between transducer and transmitter devices. A transducer creates a low-level electronic signal in response to changes in applied or differential pressure. As with transmitters, transducers feature an internal sensor that converts the applied force into an electrical signal, from which the measurement is derived.
The paper deals with the method of gearbox diagnostics fault detection, and shows that using: design, production technology, operational, change of condition (DPTOCC) factors analysis leads to the inference of gearbox diagnostic information. In the paper is a review of the current possibilities for using mathematical modeling and computer simulation for investigating the dynamic properties of gearbox systems. Computer simulation of dynamic behavior of gearboxes is a powerful tool for supporting gearbox diagnostic inference.
The paper deals with the method of gearbox diagnostics fault detection, and shows that using: design, production technology, operational, change of condition (DPTOCC) factors analysis leads to the inference of gearbox diagnostic information. In the paper is a review of the current possibilities for using mathematical modeling and computer simulation for investigating the dynamic properties of gearbox systems. Computer simulation of dynamic behavior of gearboxes is a powerful tool for supporting gearbox diagnostic inference.
In its simplest form, vibration can be considered to be the oscillation or repetitive motion of an object around an equilibrium position. The equilibrium position is the position the object will attain when the force acting on it is zero. This type of vibration is called "whole body motion", meaning that all parts of the body are moving together in the same direction at any point in time.
In its simplest form, vibration can be considered to be the oscillation or repetitive motion of an object around an equilibrium position. The equilibrium position is the position the object will attain when the force acting on it is zero. This type of vibration is called "whole body motion", meaning that all parts of the body are moving together in the same direction at any point in time.
As the infrared industry continues to develop, documentation will become more important and required. Infrared video recording and data logging creates a database, making the thermographer and the end user accountable for all items surveyed, thereby reducing the liability and improving the quality for both the end user and infrared thermographer.
As the infrared industry continues to develop, documentation will become more important and required. Infrared video recording and data logging creates a database, making the thermographer and the end user accountable for all items surveyed, thereby reducing the liability and improving the quality for both the end user and infrared thermographer.
During Academy of Infrared Training courses, we see many students who have purchased an infrared camera that is not suited for their intended use. These students have put their trust in a camera salesperson, and, many times, that salesperson was solely interested making a sale. Later, these students are disappointed to find out that the camera is not truly suited for their application. This article aims to help the camera buyer understand what basic camera specifications mean, and also help them determine what type of camera and options are suitable for their application. If you note your answers to questions throughout this article, by the end you should have a custom list of applicable specifications and options.
During Academy of Infrared Training courses, we see many students who have purchased an infrared camera that is not suited for their intended use. These students have put their trust in a camera salesperson, and, many times, that salesperson was solely interested making a sale. Later, these students are disappointed to find out that the camera is not truly suited for their application. This article aims to help the camera buyer understand what basic camera specifications mean, and also help them determine what type of camera and options are suitable for their application. If you note your answers to questions throughout this article, by the end you should have a custom list of applicable specifications and options.
The purpose of this paper is to introduce condition monitoring and reliability engineers to the principles of using ultrasound for the assessment of machine condition. Ultrasound can be a complimentary technology to vibration, thermography and lubrication monitoring. It must be emphasized that it is rarely successful as a stand alone technology for effective machine condition assessment and subsequent required maintenance planning. This paper concentrates on the use of airborne ultrasound as a complementary technique particularly for machinery that may be inaccessible due to guards or hazardous locations.
The purpose of this paper is to introduce condition monitoring and reliability engineers to the principles of using ultrasound for the assessment of machine condition. Ultrasound can be a complimentary technology to vibration, thermography and lubrication monitoring. It must be emphasized that it is rarely successful as a stand alone technology for effective machine condition assessment and subsequent required maintenance planning. This paper concentrates on the use of airborne ultrasound as a complementary technique particularly for machinery that may be inaccessible due to guards or hazardous locations.
