| 摘要 |
A method for controlling a heat tracing circuit automatically determines power off time durations. The method calculates the off time duration based on the temperature of a process pipe measured at the end of an initial predetermined power off time interval together with a particular process pipe set point temperature as well as a dead band temperature that is greater than the set point temperature. The set point temperature is based on the process media, heating cable parameters and installation environment of the process pipe. The power off cycle time duration is limited to the time it takes the process pipe temperature to reach the set point temperature, thus limiting the number of on/off cycles of the heat tracing circuit and consequently the life of the circuit components.
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