machine not getting up to set temperature-rotary (drum) machine

machine is not heating up completely to set temperature. ie temperature set for 400 and machine only getting to 360 after several hours.

on drum machines–This is usually an issue of not getting the full power (not full voltage or not all three phases of power).

check fuses or circuit breaker. make sure all three phases or two phases have proper voltage. measure line to line, not line to ground as the machines are typically wired in delta so the voltage can feed back through the heaters if measuring line to ground.

check circuit breaker output voltages.

check contactor or ssr voltages. With the machine ON and the temperature controller turned on and heating up, measure the voltage of each channel between input and output. should be 0V. if you measure a voltage, this channel if bad and you are measuring the feedback voltage through the heaters.