a recent article published by machinedesign.com, written by rogelio castaneda and oscar rivera of sensata technologies, explains the thermal challenges that solid-state relays (ssr) face and some of the solutions that can prevent failure due to excessive heat.

solid-state relays have thermal challenges that need to be overcome.
(wikimedia commons)

as the article noted, solid-state relays have become more common in the past 30 years, taking some of the market share from electromechanical relays. one of the main reasons for this is the longevity of solid-state electronics that require no moving parts.

the article explained, “the average lifespan of electro-mechanical relays is in the range of hundreds of thousands of cycles, compared to 5 million hours of three-phase solid-state relays.”

while there are a number of benefits to ssr, they do conduct heat when conducting current and require thermal management to ensure proper functionality. “should overheating occur, diagnosing and replacing a damaged ssr can take time while the assembly line or manufacturing system is down and out of service, running up even more costs,” the article continued.

to combat overheating, new ssr have a thermostat built in to monitor the relay and make sure that it is operating under safe conditions. the relay will shutdown if the internal temperature exceeds the maximum set by the manufacturer.

“this built-in thermal protection completely prevents overheating conditions by providing a trip before equipment damage can occur,” the article added, “which can help reduce maintenance costs and production downtime. power is automatically turned on again when the temperature has cooled down to within the normal operating range.”

the thermal management protection that is built into the relay can also help designers identify issues within the system, such as “incorrect heat sinking capacity in the ssr or system; poor installation resulting in insufficient heat sinking contact; heat dissipation efficiency of the system;” and more.

read the full article at http://www.machinedesign.com/mechanical/prevent-solid-state-relay-failure-thermal-protection.

for more about the need for thermal characterization of solid-state drives, read https://www.qats.com/cms/2017/11/02/thermal-characterization-ssd-important.