The temperature-resistant housing around the lens of this flame scanner allows it to be attached directly on the furnace and operate at 250°F.

The scanner converts ultraviolet radiation from the burner flame into an electrical signal. The UV radiation is gathered through a quartz lens and sent to a solid state detector mounted on a printed circuit board contained inside an aluminum housing in the furnace's viewing port. "A microcomputer processor converts signals from the detector into digital signals indicating whether the flame is on," said Gary Wild, the electronic engineer and engineering manager at GN Electronics who led the development of the scanner. "A controller uses that information to regulate gas flow to the furnace."

A major design consideration for Wild and his colleagues was making the lens housing impervious to prolonged exposure to temperatures up to 250°F, and to make it liquid- and dustproof, too. They chose to make the lens housing out of glass fiber-reinforced polyphenylene sulfide plastic supplied by DSM Engineering Plastic Products of Reading, Pa.

GN Electronics chose PPS because of its dimensional stability over the operating range of the flame scanner. The material is able to withstand temperatures of 425°F and possesses a very low coefficient of thermal expansion.

"We decided to machine the scanner housing as opposed to molding it, which is the typical practice with plastic parts, because machining was more economical, and facilitated the close tolerance threads required of the housing," Wild said.

The utility faced the challenge of verifying that none of the braces on more than 800 transformers in its system contained similarly high levels of PCB-laden fluid. Drilling holes in each vacuum brace was considered, but the time and cost involved made it impractical. Con Ed turned to Structural Integrity Associates Inc., based in San Jose, Calif., to develop a quick, nondestructive procedure.

The SI designers, led by Matthew Dowling, a mechanical engineer and ASME member, built a mockup of the vacuum brace and devised an ultrasonic technique to detect liquid inside the brace. "We introduced ultrasound via transducer and received the return signal with a digital flaw detector that displayed the signal," Dowling said. "The signal was analyzed by the technician to determine whether it was filled with liquid."

Following a successful field demonstration, the technology was implemented on Con Edison's transformers. Approximately 30 percent of the vacuum braces were found to contain liquid. In those cases, maintenance crews drilled holes in the braces and drew samples for testing. Several braces were found to contain PCB levels higher than desired, and these cases were corrected by the utility. All testing of easily accessible transformers was accomplished in one month, a fraction of the time the drilling and sampling method would have taken.

The 900X pressure regulators convert voltage signals into proportional pneumatic outputs to provide precision control in grinding machinery applications, among others.

The 900X regulators can be mounted on a wall, panel, pipe, or rail. At the heart of the new regulator is a bimorph piezo-actuator that receives 4-20 mA signals over wires from programmable logic controllers or process computers. The piezo-actuator provides the desired pressure up to 100 lbs. per square inch gauge within plus or minus 0.1 percent accuracy.

The new monitor is typically installed on the three-phase voltage supply lines of a motor by means of its eight-pronged plug-in, which matches standard 600V ac octal sockets. Operators select the monitor's nominal input voltage by turning a knob. A microprocessor within the PLMU inscribed with proprietary SSAC software senses under- and overvoltage, voltage unbalance, phase loss, and phase reversal.

The microprocessor automatically selects the voltage range, specifically, 240 and 380V ac for 50 Hz, and 240 and 480V ac for 60 Hz. When all voltages are acceptable, the output relay energizes and a light-emitting diode indicator lights green. In the event of a fault in voltage, the LED flashes green during the trip delay, then glows red when the output relay de-energizes. The monitor resets automatically when the fault is corrected.

This made it necessary to design into the inspection system a linear slide mechanism with extremely high accuracy, to prevent the laser mechanism from moving back and forth while it is translated by the micrometer dial. The Retina engineers soon faced a serious challenge. The accuracy of the linear slides that they evaluated for the application was not high enough to maintain the quoted accuracy of the inspection system. The back-and-forth movement of the slide threw the laser out of alignment.

Retina Systems engineers had heard of N-series ball slides, supplied by Del-Tron of Bethel, Conn., which had an accuracy within 0.0005 inch for each inch of travel and repeatability of 0.0002 inch, and decided to give it a try.

To provide even greater accuracy for this critical application, Del-Tron engineers offered to add preload to the slides, bringing their accuracy within 0.0002 inch, and maintain that accuracy on a consistent basis. Retina designed up to six of these slides into typical systems designed to inspect thread fasteners.

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