The SmartMold Hot Runner Mold Box saves time and money by protecting thermocouples (t/c) in the hot-half and t/c modules in the hot runner controller from direct-shorted heaters while also enhancing the accuracy of t/c temperature readings during normal operating conditions.
Thermocouple Protection from a Direct-Shorted Heater
Notice the heater wire is directly connected to the hot-half; replicating a directly shorted heater. There were zero ohms on the t/c circuits in this condition.
A positive temperature coefficient (PTC) device allows the amount of current generated during the normal operation of a thermocouple to flow through but shuts down when the current flowing through becomes too high. Unlike conventional fuses, the PTC resets itself when the current drops to a normal level. The time it takes to trip the device (time-to-trip) depends on the current and falls rapidly as the current increases.