How to Avoid Thermocouple Signal Interference

Electromagnetic interference is produced by a variety of mechanical equipment, power circuits, and frequency conversion devices in the actual operation site of injection molding workshops. This can easily result in data floating, inaccurate temperature feedback, distortion of the hot runner thermocouple temperature signal, and further disruption of the hot runner temperature control system. Thermocouple temperature signals can be transmitted steadily and accurately by implementing efficient anti-interference methods.

First, the most fundamental anti-interference measure is to standardize thermocouple wiring layout. Signal connecting wires for hot runner thermocouples must be made of special high-temperature shielding wires that have an integrated metal shielding layer and are capable of successfully isolating external electromagnetic wave interference. In order to prevent strong current power lines from interfering with weak current temperature measurement signals, thermocouple signal lines must be laid apart from high-power equipment power lines, maintain a safe distance of more than thirty centimeters, and avoid parallel binding and mixed wiring arrangements. It is prohibited to haphazardly pull thermocouple wires close to high-temperature motor equipment, frequency converters, and injection molding machine hosts.

Optimize the temperature control system's grounding connection method, maintain robust and dependable hot runner temperature controller grounding, guaranty unified equipotential grounding of all thermocouple shielding layers, and prevent multi-point messy grounding that results in loop interference signals. To lessen the impact of interference on temperature measurement data, regularly check the firmness of the grounding wire, remove rust and oxide layers at grounding connection positions, maintain the grounding system's good conductive performance, and smoothly discharge external interference signals to the ground.

When installing thermocouples, make sure the detecting head and hot runner metal shell are adequately insulated. Additionally, prevent multi-point contact conduction between the thermocouple shell and hot runner metal components to prevent induced current interference. Choose fully enclosed, high-isolation thermocouple goods for hot runners used in high-frequency interference workshops, fortify internal anti-interference structural design, and improve resistance to complex on-site electromagnetic signals. In addition to preventing internal shielding layer fracture and shielding failure due to wire harness damage, which would cause a sudden fall in anti-interference performance, limit excessive bending and repeated twisting of thermocouple signal wires in daily usage.

Additionally, turn on the built-in digital filtering function, adjust the hot runner temperature controller's internal signal filtering parameters sensibly, set the filtering intensity appropriately, filter out instantaneous floating interference signals, and make the temperature data displayed tend to be stable. Clean dust, oil, dirt, and metal powder that have accumulated on thermocouple wiring terminals and plug connectors on a regular basis. Keep wiring joints clean and in good contact to prevent unreliable interference signals. Solve common issues like thermocouple temperature floating, inaccurate temperature measurement, and abrupt temperature jump by using a variety of anti-interference techniques in wiring, installation, grounding, and equipment parameter setting. This will guaranty that the hot runner temperature control system operates steadily for an extended period of time.