Evaluation of the Thermal Characteristics of Solid State Relays Used for Heat Tracing Applications




Miller, Nicholas

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Unlike its predecessor, the electromagnetic relay, a solid state relay contains a switching capability with no moving parts. This process is accomplished through the utilization of solid state devices within the relay structure. Solid State relays can be photo-coupled, transformer-coupled, and hybrid [1]. This research project focuses on just the photo-coupled relays. The theory of the solid state relay (including how the relay works), a specially designed test involving these relays and the intriguing results of the test are discussed in detail in this thesis. The test that we designed, implemented, and discussed is pertains to the heat tracing industry. Heat tracing is the external application of heat to pipes, tanks, and instrumentation. Solid state relays are used as control switches which communicate with a heat tracer telling it when to turn on and off. The power through the relays while in the “on” state will result in internal heat formation. Thermal properties of the solid state relay expose their limitations in the heat tracing field. Once these limitations are tested and analyzed, decisions can be made about the applications of solid state relays used for a particular heat tracing application.



Solid state, Relays, Heat tracing, Thermal characteristics


Miller, N. (2009). <i>Evaluation of the thermal characteristics of solid state relays used for heat tracing applications</i> (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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