Nine problems in the use of infrared thermometers need attention
The role of infrared thermometer in the use of electronic platform is ubiquitous, because the resistance strain infrared thermometer itself is a strong, durable and reliable electromechanical product, but in order to ensure the accuracy of the test, but the electronic platform should pay attention to it in use Question, so what should be paid attention to when using an infrared thermometer? The following describes some nine aspects that must be paid attention to when using an infrared thermometer:
1. Try to set up some "baffles" around the infrared thermometer, or even cover the thermometer with a thin metal plate.
This can prevent debris from contaminating the thermometer and some movable parts, and this "contamination" often makes the movable parts uncomfortable and affects the weighing accuracy. The following methods can be used to judge whether the system has movement discomfort. That is, add or subtract about one-thousandth of the rated load on the weighing platform to see if the electronic platform weighing display responds, and if there is a reflection, it means that the movable part is not "contaminated".
2. All wires leading to or from the display circuit should use shielded cables.
The connection and grounding point of the shielded wire should be reasonable. If it is not grounded through the mechanical frame, it is grounded externally, but the shielded wires are not grounded after being connected to each other, and are floating.
Note: There are 3 thermometers that are fully parallel connected. The thermometer itself is a 4-wire system, but it is replaced with a 6-wire connection in the junction box. The readout circuit of the output signal of the thermometer should not be placed in the same box with devices that can generate strong interference (such as silicon controlled devices, contactors, etc.) and devices that generate considerable heat. If this cannot be guaranteed, it should be considered Set up a baffle between them to isolate them, and install a fan in the box. The electronic circuit used to measure the output signal of the thermometer should be equipped with an independent power supply transformer as much as possible, instead of sharing the same main power supply with contactors and other equipment.
Nine problems in the use of infrared thermometers need attention
3. Infrared thermometers should use twisted copper wires (cross-sectional area of about 50mm2) to form an electrical bypass to protect them from the hazards caused by electric welding current or lightning strikes. In the use of the thermometer, strong heat radiation must be avoided, especially strong heat radiation on one side.
4. Prepare for electrical connection (such as the signal cable of the thermometer, do not arrange it in parallel with the strong electric power line or control line (for example, do not put the signal line of the thermometer, the strong electric power line and the control line in the same pipeline). If they must be placed in parallel, then the distance between them should be kept above 50CM, and the signal line should be covered with a metal tube.
5. Try to use structural accessories with automatic positioning (resetting), such as spherical bearings, joint bearings, positioning fasteners, etc.
They prevent certain lateral forces from acting on the thermometer. It should be noted that some lateral forces are not caused by mechanical installation, such as the lateral force caused by thermal expansion, the lateral force caused by wind force, and the lateral force caused by the vibration of the agitator on some container scales is not caused by mechanical installation. . Some scales have some accessories that must be connected to the scale body (such as the feeding pipe of the container scale, etc.), we should make them as soft as possible in the direction of the loading spindle of the thermometer to prevent them from "eating" the temperature measurement. The actual load of the instrument will cause errors.
6. Handle with care, especially the small-capacity thermometer made of elastic body made of alloy aluminum. Any impact or drop may cause great damage to its measurement performance. For large-capacity infrared thermometers, generally speaking, it has a large dead weight, so it is required to use appropriate lifting equipment (such as chain hoists, electric hoists, etc.) as much as possible during handling and installation. The mounting surface of the base where the thermometer is installed should be flat and clean without any oil film, glue film, etc. The installation base itself should have sufficient strength and rigidity, generally higher than that of the thermometer itself.
Nine problems in the use of infrared thermometers need attention
7. Although the infrared thermometer has a certain overload capacity, the overload of the thermometer should still be prevented during the installation of the weighing system. It should be noted that even short-term overloading may cause damage to the thermometer.
During the installation process, if it is really necessary, you can replace the thermometer with a block with the same height as the thermometer, and then replace the thermometer. During normal operation, the thermometer should generally be equipped with mechanical structural parts for overload protection. If a screw is used to fix the thermometer, a certain tightening torque is required, and the screw should have a certain screw-in thread depth. Generally speaking, the fixed screw is due to the use of high-strength screws.
8. In any case, the power line and the control line should be twisted together, the joint degree is 50 turns/m. If the signal line of the thermometer needs to be extended, a special sealed cable junction box should be used. If this kind of junction box is not used, but the cable is directly connected with the cable (soldered end), special attention should be paid to the sealing and moisture resistance. After the connection is completed, the insulation resistance should be checked and it must meet the standard (2000~5000M). If necessary, The thermometer should be recalibrated. If the signal cable is very long and high measurement accuracy must be ensured, a cable compensation circuit with a relay amplifier should be considered.
9. Level adjustment
Level adjustment has two aspects. One is that the installation plane of the installation base of a single thermometer should be adjusted with a spirit level; In the weighing system with more than three instruments, more attention should be paid to this point. The main purpose of this is to make the loads on each thermometer basically the same. The loading direction of each electronic platform infrared thermometer is determined, and when we use it, we must load the load in this direction. Lateral forces, additional bending moments, and torque forces should be avoided as much as possible.
