Common faults and troubleshooting of far-infrared ceramic heaters

Author: Electric Heating Craftsman - vV
Link: https://zhuanlan.zhihu.com/p/361982877
Source: Zhihu
Copyright belongs to the author. For commercial reproduction, please contact the author for authorization. For non-commercial reproduction, please cite the source.

I. Initial Determination of Heater Authenticity 1. Structure: Our products are overmolded. That is, the heater body and mounting slot are clearly distinguished by color. 2. The front of the logo displays the "product model" and parameters such as product power, voltage, and maximum temperature. Is the CE mark printed on the back? 2. Heater Application Principle: Infrared radiation, λ = (2-10) μm. Most objects have good absorption within this wavelength range. The closer the heater's T, the lower its λ, and the stronger its penetration. According to Wayne's law, the closer the distance, the higher the radiation intensity (60%-70% of the radiation intensity at d = 70 mm; adjust the distance appropriately based on production requirements). 3. Regarding Heater Materials: 1. Regarding Heating Wire Material: Kanthal AF: Aluminum-chromium-iron. According to Ohm's law: R = U²/P, the resistance value can be calculated. Power P↑, resistance R↓, and heating wire diameter L↑. 2. Regarding K-Type Thermocouples: Materials: Nickel-chromium (+) - Nickel-silicon (-); Resistance: 0.3-5Ω. K-Type thermocouples have an error of ±0.4%t when measuring temperature. Grade; Maximum temperature can reach 1000°C, temporarily up to 1200°C; 3. Ceramic Body Formula; 4. Thermal Insulation: THI: Aluminum Silicate; 5. Built-in Wire Heater: Built-in thermocouple wire: Operating temperature range -200°C-1200°C; 6. External Wire: ① Nickel conductor: Stranded wire, 2.5 mm², 11A, nickel, 500°C max; ② Thermocouple wire: Solid wire, nickel, 400°C max; ③ Compensation wire: Stranded wire, 1.5 mm², 100°C max. IV. Heater Installation: Mounting hole 15×40, mounting plate thickness ≤1.5 mm; V. Heater Quality Inspection: 1. Heater Quality Inspection without Thermocouple: ① Resistance can be calculated using Ohm's law: R=U²/P. If the measured value deviates from the theoretical value within +/-6%, this is normal. Resistance values vary at different temperatures. If not within this range, please contact our sales representative for a replacement. 2. Quality Inspection for Built-in Thermocouple Heaters (Type K): ① Check the heating wire as for heaters without thermocouples. ② If step 1 checks fine, continuously test the thermocouple resistance on the heater; it should be between 0.3 and 1Ω. ③ After wiring correctly, power on the heater for 20 minutes and test the thermoelectromotive force across the thermocouple. If the thermoelectromotive force continues to rise, the thermocouple is considered faulty. (If there are any quality issues, please contact our sales representative for a replacement.) VI. Precautions Before Use: 1. Thermocouple Type Matches: The thermocouple type on the temperature controller should match the built-in thermocouple type on the heater. 2. Wire the thermocouple correctly. The end with the dark green marking on the thermocouple wire is the positive terminal and should be connected to the positive terminal on the temperature controller. 3. Before using the temperature controller, set the temperature controller to the normal operating value for the system and power on for auto-tuning. VII. Temperature Display Issues: 1. "Temperature Drift" Issue Description: When the displayed actual temperature reaches near the maximum setpoint, the actual operating temperature fluctuates significantly (the allowable fluctuation range varies depending on the system), potentially by tens of degrees Celsius. Cause: Temperature controller setup issue. Troubleshooting: ① When using a temperature controller and thermocouple for the first time, auto-tuning the temperature controller is required to adjust the temperature controller parameters to match the thermocouple's performance. For details, please refer to the operating manual of the corresponding temperature controller. ② If the fault still persists after following solution ①, power on the heater for 20 minutes and test the thermoelectromotive force at both ends of the thermocouple. If the thermoelectromotive force continues to rise, it can be determined that there is no problem with the thermocouple heater. Replace the thermocouple wire and temperature controller in turn to check the cause. If the voltage value does not continue to rise, please contact our sales staff in time to replace the heater. 2. The temperature continues to drop (an abnormal alarm is displayed after reaching a certain temperature). Problem description: The temperature reading on the temperature controller continues to drop. Cause classification: The wiring is connected incorrectly. Troubleshooting plan: ① Check whether the thermocouple wire and compensation wire are connected correctly. The built-in thermocouple wire has a dark green mark on the positive end - the positive pole of the thermocouple wire (the positive pole of our company's thermocouple wire is green) - the positive pole of the compensation wire (the positive pole of our company's compensation wire is green) - the positive pole of the temperature controller. ② If solution ① checks correctly and the fault cannot be eliminated, please check the heater quality according to the previous fifth item - Heater quality inspection. If the heater problem is eliminated, please replace the temperature controller to determine whether it is a quality problem of the temperature controller. If it is a quality problem of the heater, please contact our sales as soon as possible for a replacement product. 3. The temperature rises to a certain value and then begins to drop. Problem description: The temperature rises when the power is turned on, but begins to drop before reaching the set temperature. Problem classification: Thermocouple wire quality problem Troubleshooting plan: ① Replace the thermocouple wire and check the thermocouple wire quality problem. If it is a thermocouple wire quality problem, please replace the thermocouple wire to troubleshoot the problem. ② If it is not a thermocouple wire quality problem, please check the heater quality according to the previous fifth item - Heater quality inspection. If it is a heater quality problem, please contact our sales for a replacement. If it is not a heater quality problem, please replace the temperature controller to check the cause. 4. Thermocouple type setting error Problem description: Abnormal temperature control cause classification: Temperature controller setting problem Troubleshooting plan: ① Check the temperature controller settings and check the thermocouple type. After setting it correctly, the temperature controller will self-tune. ② If it still does not work normally, please check whether there is a quality problem with the heater. 5. When several heaters are used simultaneously, only some of them experience temperature display issues. Problem Description: Several heaters are used simultaneously, but only a few of them are malfunctioning. Troubleshooting: ① Check that the thermocouple's positive and negative terminals are correctly wired (the dark green marked terminal is the positive terminal). ② If the wiring is correct, measure the resistance of the heating wire and the thermocouple. The resistance of the heating wire can be calculated using R=U²/P. The thermocouple's resistance should be between 0.3-1Ω. If both resistances are normal, power the heater for 20 minutes and measure the thermoelectromotive force (TEF) across the thermocouple. If the TEF continues to rise, the thermocouple heater is considered faulty. If the problem is quality, please contact our sales representative for a replacement heater. ③ If solution ② fails to resolve the issue, but the heater still malfunctions, replace it with a working heater and see if it works properly. If it still doesn't work properly, check the wiring. If it works properly, please contact our sales representative and return the product for inspection by our professional staff. 6. Problems caused by sleeve material issues. Description: After replacing the wiring connector, the wiring sleeve frequently burns out during use. Cause: Incorrect sleeve material selection. Troubleshooting: The wiring space on the back of the heater is relatively hot during use. Using a wiring sleeve made of materials such as copper that are not heat-resistant can cause this problem. The correct approach is to use a nickel alloy or stainless steel wiring sleeve.