In summary, the ACS and the ACST are types of AC switches with built-in overvoltage protection. These devices have very high immunity to noise, dV/dt, and high commutation capability, dI/dt, and are available in a standard 125°C and a 150°C version. Current ratings for these switches are up to 16 A. The H series which can be used in higher ambient temperature applications or where a smaller heat sink is desirable. With current ratings up to 30 A the switch commutation of the H series is guaranteed at 150°C. The Triac family begins with the BTA, an isolated package and the BTB which is non-isolated. These switches have a standard junction temperature of 125°C and current ratings up to 40 A. The T series features improved commutation and dV/dt and are less expensive than the high-performance ACS switches. Selectable in 125°C and 150°C junction temperatures, the current ratings for the AT series switches is up to 16 A. The A.S.D. series consists of one part, STCC08, used for monitoring the AC switch to verify that it is working properly. The TPDV series is a series of rugged industrial AC switches with voltages up to 1,200 V and current ratings up to 40 A. SCRs are unidirectional switches which ST manufactures in both standard and sensitive gate current trigger devices. SCRs feature withstanding voltages up to 1,200 V and are available in standard and high junction temperature devices, with RMS current ratings up to 85 A.