Arcing due to loose fuse bolt
Infrared Thermography (IR) has been successfully employed as a diagnostic tool in commercial applications since the early 1970's. Technological advancements in sensitivity, accuracy and data display have expanded its use throughout various industries at the same time its availability as a consulting service has brought costs within every operating budget.
With occupant safety, the protection of capitol equipment, and energy conservation all being synonymous with proper electrical and mechanical maintenance, IR has established itself a leading tool of successful building operation and management. Infrared thermography's non-contact, non-destructive form of measurement provides a cost effective, real time and on-line analysis of any building's electrical, mechanical and physical operation.
A/C Package Unit Switch
Burned Phase "B" wire
Often Overlooked - Motor Connections
Un-insulated Heating Duct
Saturated Roof of Office Building
A Brief Background
Infrared energy is radiated by every physical object in an amount proportional to its temperature. While such energy is invisible to the human eye, it can be measured, recorded and visually presented in a variety of useful formats through the use of today's advanced technology IR cameras and image enhancement computer programs. The resulting information has proven itself invaluable in identifying hidden physical, electrical and mechanical defects, and has been employed within the building management industry for well over a decade. Properly applied, IR technology provides a secondary benefit through its ability to reduce unnecessary maintenance by predicting the occurrence of future operating problems. Typically, an infrared inspection will provide advance warning of an equipment failure or fire threat months to years prior to its normal occurrence. In electrical systems, loose, corroded or poor connections produces heat. Heat, in return, raises electrical resistance - thereby creating additional heat. This runaway cause and effect condition eventually results in an electrical failure and often fire and/or explosion. For mechanical equipment, shaft misalignment, inadequate lubrication, or some other frictional defect is typically the cause of the heat generated. The resulting heat product further deteriorates any lubricants, bearings, seals, or other mechanical components, and again leads to an inevitable failure of the component. Such mechanical failures typically have secondary and costly consequences.
For building management interests, the benefits of IR testing are many. Infrared thermography can quickly expose hidden stresses, damaged components, loose connections, unbalanced loads and other faults in electrical equipment. IR can diagnose problems in rotating machinery by permitting the inspection of the motor shell, motor bearings, load bearings, and other transmission components under physical load. In electrical applications, loose, dirty, corroded or oxidized connections or contacts will produce infrared energy proportional to the amount of heat generated and dissipated due to their increased electrical resistance. In friction generating equipment, heat buildup will show prominently over the ambient surroundings.
For various other applications, the movement of heat energy can be visually traced from one medium to another. It offers additional uses in detecting water leakage in roofs, in finding insulation faults and steam trap malfunctions, in identifying HVAC air distribution patterns and building envelope energy loss, and by detecting underground pipeline leakage.
It should be noted that Infrared Testing is not an absolute science. It cannot provide certainty until further testing, (nondestructive and/or destructive) is completed, or disassembly of the component and/or components is completed to determine if a deficiency or anomaly actually exist. This further testing will also help determine the root cause of an existing deficiency or anomaly.
A final report of all areas found to exhibit elevated or atypical temperatures could then be used by operating personnel to both resolve immediate problems as well as plan or alter future preventive maintenance schedules. Some of the many applications for infrared thermography and the potential financial savings are:
|Electrical - Poor Connections||Failure - Energy Loss - Voltage Irregularities - Fire|
|Electrical - Overload||Failure - Insulation Deterioration - Fire|
|Electrical - Unbalanced Phase Current||Motor Overheating - Wiring Overload|
|Electrical - Corona Discharge||Component & Insulation Deterioration - Failure|
|Mechanical - Bearings||Bearing Failure - Damage to Rotating Parts|
|Mechanical - Couplings||Coupling Failure - Lost Production - Parts Damage|
|Mechanical - Drives||Drive Failure - Lost Production - Parts Damage|
|Mechanical - Leaking Steam Traps & Valves||Energy Loss - Product Loss - Pollution|
|Mechanical - Thermal Insulation - Refractory||Energy Loss - Process Upset|
|Building Heat Loss||Energy Loss - Employee & Tenant Comfort|
|Building Roof Moisture Penetration||Energy Loss - Roof Structure Deterioration|
Advantages of Infrared Thermography
Infrared thermography falls within a group of diagnostic tools classified as nondestructive testing. That is - it neither damages nor alters that material or component which it is evaluating. The fundamental advantage of IR inspection is its ability to identify previously unavailable operating information pertaining to critical components and equipment. In many cases, that information is the surface temperature of high voltage electrical equipment, switches, conductors and connections. In others, it may be an equally hazardous situation such as a rotating body, or a piece of equipment, which exists in an inaccessible location. Because IR operates from a safe distance and without any physical contact, it is possible to survey any physical condition having a thermal differential and not interfere in the operation of the subject equipment. It is possible to survey an entire building's main electrical grid, for instance, without a major shutdown.
Infrared inspection allows for the most efficient use of building personnel since it can typically be completed at only a small fraction of the time normally required to visually inspect and tighten each and every electrical connection. Significant savings are obvious over a manual inspection. IR also offers a higher degree of accuracy at locating faults, and addresses additional equipment problems such as unbalanced loads, motor overheating, bearing failure, switch contacts, etc. - those defects which would not likely be addressed using manual inspection procedures.
IR also provides information under actual operating load conditions. Borderline problem areas, otherwise undiscovered during an off line physical inspection, can be observed in real time only through IR imaging. Other advantages lie in the ability to save unnecessary maintenance costs by identifying only those components, which are in need of repair.
Limitations of Infrared Thermography
Limited Line-of-Site Visibility
Many times, electrical enclosures such as Motor Control Centers, Distribution Panels and Main Switchgear Cabinets are installed with their backsides against a permanent wall (figure 1). This type of installation prohibits a clear line-of-site visibility to the wire/bus detail, therefore impossible for the thermographer to scan all of the electrical components and detail.
The picture to the left is a typical Motor Control Center (MCC) installation against a permanent wall which is found in many commercial and industrial facilities.
Jaw clamps are used to make the connection to the interior bus bars. The thermographer does not have a clear line-of- site visibility to these connections with this type of installation, which can prohibit the detection of heat related anomalies.
Clear Line-of-Site Visibility
The below photos show bus detail of a Motor Control Center that was not installed against a permanent wall. This installation allows for back cover removal and inspection (figure 2). The heat rise at the jaw clamps (figure 3) was not detectable from the front of the MCC. If this Motor Control Center was installed against a wall, inspection of the bus detail would not have been possible. This example illustrates the importance of a clear-line-of-site-visibility to all electrical enclosures to be scanned.
Figure 2 – Back cover removal
Figure 3 – Heat Rise at jaw-clamps
All equipment and components in which we are requested to scan, but do not have a clear line-of-site visibility will be noted as “Limited Visibility” or “Not Tested” in your final report.
Procedures and Specifications
Prior to the actual field testing, ECI shall conduct a walk through and/or interview the client from the facility to review the general types of electrical equipment, panels, switchgear, etc. in use and to be scanned. The scope of the testing to be performed and the depth of investigation into the various electrical equipment types will be discussed with the electrical and/or mechanical departments; this in order to best estimate the number of days of field testing which will be required.
ECI shall not handle any electrical equipment, remove or replace panel covers, operate switchgear, or manipulate any other electrical components whatsoever. ECI shall not, in any way, be responsible for the actions taken, or not taken of any other individuals in their handling of any electrically related equipment, or for any consequences resulting from such actions.
The client must provide a Qualified Assistant - one who has the skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.
The client must provide an inventory list of the equipment to be inspected and a logical and efficient route throughout the facility. If an inventory list is not supplied, it’s the client’s responsibility to determine exactly what electrical enclosures are to be scanned. In many cases, the client can establish this inventory list by removing enclosure covers and trims prior to scheduled scan dates. It is important that all panel covers and metal trims shall be removed in order to provide visual access to any concealed wiring, terminal connections, switches, fuses and fuse components, etc.
During the actual testing dates, ECI refrains from requesting the removal of electrical covers and/or trims. This practice is based on the fact that ECI does not know the degree of electrical experience and/or the qualifications of the qualified assistant and/or building personnel you chose for the dangerous task of enclosure cover and trim removal.
Electrical enclosures that do not have covers and trims removed shall not be included into the inventory list. ECI was not hired to catalog every single individual enclosure within your facility - ECI was hired to infrared scan your selection of electrical enclosures that are most important to the operation of your facility. However, enclosures which are included on a previous inventory list or brought to our attention during our scan, but do not have the covers or trims removed or are not accessible shall be noted as such in the report, and will be judged as “Not Tested”.
Providing access to all areas enclosing electrical panels or other equipment to be surveyed shall be the full responsibility of the client.
The client must also assure that the equipment to be inspected is under adequate load (minimum 40%), create satisfactory loads when necessary, and allow sufficient time for recently-energized equipment to produce a stable thermal pattern.
Visible light is 0.4 to 0.7 microns in wavelength, with the color red found at 0.7 microns. Infrared light is longer than visible light and is represented in the 0.8 to 15 micron range. (As a reference, one micron is one millionth of a meter) Most IR cameras operate in the 2-14 micron range and are categorized as either short wave (2-5 micron) or long wave (8-14 micron). Long wave IR cameras have a greater sensitivity to our "normal" range, i.e. (0 – 400°F.) Infrared light energy exists even in cold environments and can be measured in temperatures as low as minus 20 degrees Fahrenheit. The equipment employed by ECI in its Predictive Maintenance Service is a Mikron 7515 or 7815. This unit operates in the upper 8-14 micron band, is energy efficient, compact and requires no coolants to operate - thereby allowing the IR thermographer to dedicate more attention to the actual electrical inspection.
The high resolution display of these imagers allows for an immediate thermal analysis of any object and, under ideal conditions, can provide a temperature resolution as small as one half degree Fahrenheit. This fully-radiometric imager produces Color digital data for immediate viewing.
Various standards or guidelines for Delta-T based priorities have been established according to different infrared organizations and authorities. Of those standards, ECI follows N.E.T.A. Maintenance Testing Specification, for electrical equipment, which is in accordance with the American Society for Nondestructive Testing Recommended Practice No. SNT-TC-1A.
All technicians’ employed by ECI are certified with the Infraspection Institute (www.infraspection.com). Infraspection Institute is the oldest independent infrared training and certification firm in the world. Founded in 1980, Infraspection Institute has trained and certified nearly 10,000 thermographers worldwide. They have shaped the infrared industry through training, technical consulting, technical publications, research, standards development, and software publishing.
Recommended Levels of Testing
According to NFPA - routine infrared inspections of energized electrical equipment should be performed annually prior to shutdown. More frequent infrared inspections, for example, quarterly or semiannually, should be performed where warranted by loss experience, installation of new equipment, or changes in environmental, operational, or load conditions. Infrared Testing should also be performed during periods of maximum possible loading but not less than 40% of rated load of the electrical equipment being tested.
Our written report presents a photographic record of all electrical areas displaying elevated or abnormal temperatures. Detailing of each problem with an infrared thermogram, a control photograph, temperature measurements, amp readings when possible and a repair priority listing, as well as other relevant information to the location. A second copy of the infrared thermograms are enclosed for the electrician’s who will be making the repairs.
As part of the regular reporting format, we also look for and report upon any obvious electrical or mechanical deficiency not revealing itself through an elevated temperature indication. Such secondary defects shall be itemized according to defect type and location in the final report.
Possible deficiencies to report will include, but not be limited to:
|Broken Latches||Limited Visibility|
|Discolored Contacts||Missing Cover|
|Damaged Panel||Mismatched Fuses|
|Could Not Open Panel||Not Tested in Emergency Mode|
|Excessive Dirt||Panel Not Opened|
|Evidence of High Heat||Panel Cover Not Removed For Complete Inspection|
|Insulation Burned||Cover & Trim Not Removed For Complete Inspection|
|Loose Components||Stripped Cover Screws|
|Excessive Noise||Shielded Panel Trim Not Removed|
|Frayed or Exposed Insulation||Equipment Under Repair|
|Indicator Light Out||Locked Out of Service - Untested|
For sample reports or to schedule an onsite visit, please click here or contact us at 732-548-4311.
Wireless Temperature Monitoring of Electrical Enclosures
Avoid a major electrical failure—and potentially significant financial loss—with the “Delta T Alert”. This patented device, developed by Delta T Engineering, LLC, magnetically attaches to your electrical equipment covers, monitoring the Delta T (temperature differential) between the interior of an electrical enclosure and the ambient temperature of the room in which the enclosure is located.
You can configure the Delta T to collect data on a daily basis, at specific time intervals. The information may then be transmitted wirelessly to an onsite computer for analysis. Whether your panels are in a 100 degree switchgear room in Manhattan, a 20 degree warehouse in Alaska, or a 65 degree data center in Tuscaloosa, the Delta T Alert will warn you of excessive temperature rise within your electrical enclosures--well before more serious problems may occur.
Ensure the safety of your commercial building while staying on top of critical information. With one simple installation, the Delta T can spare you not only precious downtime but also expensive repairs.
Go beyond preventive maintenance with the Delta T Alert, the sensor that’s revolutionizing electrical systems monitoring. To find out more, click here www.deltatengineering.com.