I. Pre-verification Preparation: Ensure the hot runner temperature controller to be verified is in standby mode. Disconnect the power supply circuit to the field sensors in the channel to avoid damaging the terminals by hot-plugging.
Use a process signal calibrator (hot runner-specific analog signal generator) with an accuracy class ≥ ±0.05%FS. Complete the equipment self-calibration in advance to confirm that the output accuracy meets the standard.
Disconnect the field wiring of the thermocouple/RTD for the channel to be verified. Directly connect the output terminals of the signal generator to the input terminals of the temperature control channel, and clearly mark the wiring to avoid reverse connection later.
II. Full-Range Signal Injection Verification:
For thermocouple-type channels: Sequentially input four standard temperature analog millivolt signals (0℃, 100℃, 200℃, 300℃) through the signal generator, covering the normal operating temperature range of the hot runner.
For 4~20mA type channels: Sequentially input three standard current signals (4mA, 12mA, 20mA), covering the full range of industrial standard signals.
After each standard signal is injected, wait 30 seconds for stability and record the real-time display value of that channel on the hot runner temperature control panel.
III. Channel Accuracy Judgment: Calculate the deviation between the channel display value and the theoretical value for each input signal. If the deviation is ≤ ±0.5%FS, and there are no jumps or data loss, the channel accuracy is considered合格 (qualified).
If the deviation exceeds the allowable range, record the deviation value. Correction can be achieved later through zero-point calibration and gain compensation of the temperature controller channel.
IV. Fault Simulation and Linkage Verification: Inject interference pulses and open-circuit signals using a signal generator to verify whether the temperature controller's fault alarm and over-limit protection functions are triggered normally.
Confirm that the channel alarm threshold and response delay meet the equipment's factory specifications, and that there are no alarm failures or response lag issues.
V. Final Reset: After verification, disconnect the signal generator from the channel terminals and reconnect the original thermocouple/RTD field wiring according to the markings.
Power on and confirm that the channel temperature display returns to normal. Perform a short-duration temperature rise test to confirm that the signal link is normal, completing the full-process channel verification.
This set of procedures is fully adaptable to the on-site operation and maintenance scenarios of hot runner temperature control systems. It is highly efficient and accurate, and can quickly troubleshoot hidden faults such as signal channel drift and poor contact.
