This chamber is used for casting CT & PT. This chamber should maintain one constant temperature for several hours and another value of temperature for another several hours & the time should be retentive. For this application two PID’s (4 – 20mA o/p) along with Genie NX smart relay is used. For precise temperature control Unison Phase Angle Control SSR is used. In one pid set value for eg:-80⁰C for 8hrs & in 2nd pid 120⁰C for 4hrs. After 8hrs the o/p will switch to 2nd pid. When power goes and it should run for remaining time only. Hour meter feature of plc is used.