I did not regard any of the situations that I encountered using optical isolated relays as a drawback. They never gave me any problems, with one small exception. A solid state relay that controlled s solenoid valve had one of it's twi anti-parallel SCR devices fail open. So the indicator light would show that the output was active but the valve would not shift. Once I realized that the bulb was at reduced intensity the replacement effort quickly solved the problem.
My primary use of the opto-isolated relays has been as a computer interface in industrical test systems. 100,000 hours of on time before a 3% reduction in illumination, and the associated increase in turn-on time would be no problem, since the production lifetime of the product tested may not be that long. And for those very long-life products another few milliseconds of response time would not be a problem either.
The other use of opto-relays is for on-off cycling of heaters in temperature controlled systems, where electrical heater powr is cycled to control temperature. For those applications with the zero-crossing switching the problem is even less likely to be noticed or to cause problems. It might possibly have some effect in motion control systems,but that is a different realm completely.
Using wireless chips and accessories, engineers can now extract data from the unlikeliest of places -- pumps, motors, bridges, conveyors, refineries, cooling towers, parking garages, down-hole drills and just about anything else that can benefit from monitoring.
With strong marketplace demand for qualified engineers across the board that currently outstrips the available supply, there may never be a better time for engineers and project managers to advance their careers and salaries. Whether those moves are successful in the short-term and long-term is likely to depend on how the transition from one job to the next is handled.
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