Is the cause of your next production stoppage behind door No. 1, door No. 2, or door No. 3? If you''re a plant engineer worried about the condition of electrical hardware, that''s a frustrating question if the only option you have is to de-energize circuits -- and interrupt production anyway -- for a safe infrared scan. Before a new generation of IR thermal imaging equipment became available recently, plant maintenance professionals wanting to do frequent or unscheduled electrical cabinet inspections had to choose between de-energizing circuits and forcing downtime or installing costly and fragile IR-transparent sight glasses to see just a small portion of a cabinet interior with an IR camera. But a simple $50 Viewport -- requiring no IR-transparent "glass" -- now allows a thermographer to scan a panel area of 60 x 45 in. from just 12 in. away, looking through the port''s tiny 0.5 in. opening with a SpyGlass™ fisheye lens developed by Mikron Infrared.
This new technology combination of window-free Viewport and SpyGlass lens makes companywide standardization feasible and affordable, as demonstrated by industry leaders such as Exxon Mobil, Boeing, and Cargill, where thousands of Viewports have recently been installed.
The SpyGlass/Viewport system enables closed-door thermal inspections of connected electrical switchgear, while maintaining the safety barrier. A thermographer can quickly pinpoint hotspots at the best time -- while the circuits are energized and under load. Closed-door inspection allows the thermographer to work without requiring the help of an electrician to power the system down to ensure safe conditions during an open-door inspection.
Removing or opening electrical cabinet doors or panels poses an inherent risk in high-voltage, high-amperage environments. Potentially lethal arc flash conditions can be created in open-door inspections. Human error, equipment failure, and other factors can transform static conditions within the cabinet into a dangerous environment for the inspector and others in close proximity. The SpyGlass/Viewport IR system essentially eliminates the safety risk, while reducing the personnel, time, and cost related to maintaining a regular electrical cabinet inspection program.
The Benefits of Frequent Inspections
The ease, safety, and simplicity of the system are intended to encourage more frequent inspections, allowing a highly proactive electrical PM program.
One graphic example of how frequent inspections can save significant expense occurred recently at a gas enrichment plant in the western U.S. Using the SpyGlass™ Lens and Viewport system, the plant''s maintenance team discovered overheated, failing connection leads to two 4,500 hp methane compressor motors, critical to the 24/7 operation. The timely finding enabled plant managers to correct the problems on a controlled basis, avoiding costly unscheduled downtime and damaged equipment. A similar electrical connection problem at the plant previously had caused an unscheduled outage that resulted in $1 million in lost production.
An Unobstructed Field of View
The SpyGlass™ Lens and Viewport provide the clearest possible view and most accurate temperature measurement of electrical switchgear under load because the tiny port opening requires no IR transparent window or metal screen barrier that can skew thermal readings or compromise safety. IR windows, used in the past as "sight glasses" for electrical cabinets, are neither glass nor acrylic, but crystalline materials. Typically made of calcium fluoride, germanium, sodium fluoride, or zinc selenide, IR-transparent materials are expensive -- hundreds or thousands of dollars for just a few square inches -- and often fragile. Most are highly susceptible to scratching and damage from UV light or corrosive fumes. Unlike glass or acrylic, they shatter easily when pressure is applied. The most common material, calcium fluoride, is also hygroscopic, and has a reputation for dissolving in high-humidity environments, leaving gaping holes in cabinet doors. From a thermographer''s standpoint, IR windows and metal mesh screens add an unpredictable amount of transmission loss, depending on their condition, age, etc., resulting in temperature measurements that cannot be considered accurate.
The Viewport uses only a 0.5 in. aperture that is covered by a screw-on cap with an O-ring seal to maintain the integrity and safety rating of the cabinet when not in use. To prevent unauthorized access to the cabinet, a locking device for the Viewport cap is available as well. Allowing an unobstructed view of the entire cabinet''s interior, the Viewport is unaffected by moisture, dirt, UV, and corrosive environments that can degrade IR transparent windows or penetrate metal mesh covers. It never needs cleaning or replacement.
The Viewport is designed to "mate" with the cone-shaped tip of the SpyGlass lens barrel. The plastic-tipped barrel protects the lens elements from contact with the Viewport or cabinet, and provides a layer of insulation to eliminate or substantially reduce "path to ground" arc hazards. A camera lens with a metal rim in contact with an IR window can damage the window easily, and a metal mesh screen used in place of a window creates a direct path-to-ground risk through the camera and operator.
The Viewport is UL-rated and approved for installation at the OEM level or as a retrofit in the field. Suitable for both low- and high-voltage applications from 480 volts and up, it can be installed on cabinets indoors or outdoors, in either vertical or horizontal position. With its protective cap in place, it maintains NEMA 1, 2, 3, 3R and 4 Ratings.
A Broad Field of View
The SpyGlass fisheye lens, with its wide field of view (53 deg horizontal by 40 deg vertical, or 66 deg diagonal), allows easy scanning of the interior of the electrical cabinet through the Viewport, while providing a temperature measurement accuracy of ±3°C. The SpyGlass lens attaches to Mikron''s Midas or 7000 Series MikroScan® thermography cameras. With a focus range of 4 in. (10 cm) to 45 in. (114 cm) and large depth of field, the SpyGlass lens reduces the need to refocus for different electrical cabinet depths.
20-Minute Installation
The Viewport can be installed by one person in 20 minutes or less. The electrical equipment should be de-energized before installation. To install, simply open or remove the cabinet door, use a Greenlee punch to create the aperture, drill the screw mounting holes, affix the Viewport, and reinstall the door.
Versatile Applications
The Viewport can be installed on any application where an expansive and unobstructed view behind a panel or door is desired, including mechanical rooms. Motor control centers, transformer terminal boxes, air circuit breakers, motor lead boxes, and a wide range of mechanical equipment can be outfitted with Viewports.
Three styles of Viewport are available: with screw-on cap, with a locking cap, and with a glass window and locking cap.