Summer is the rainy season. It often rains and thunders. The thunder and lightning is with a strong current, in the electromagnetic flowmeter, once the lightning hit the conduction equipment, a strong current into the converter will burn the converter and power supply, and even severely burn the main control board, thunder and lightning Generally it is the nemesis of electronic products, so general electronic products or devices with electronic components need lightning protection. How can electromagnetic flowmeters be used in the summer?
First of all, the meaning of lightning protection is to prevent, then since it is prevented, it must be reflected in the installation, that is to say when installing the electromagnetic flow meter should consider the lightning protection.
The harm caused by lightning to electromagnetic flowmeters:
1. Lightning strikes the instrument through the power supply.
2. Lightning generated at the same time with the strong magnetic field instrumentation electronic components produce magnetic induction, and instantly generate strong voltage and current, breakdown insulation burn out the instrument.
3. Lightning impulse waves invade the flowmeter through a wireless network and burn out communication chips or meters.
There are mainly 7 following lightning precautions:
1. Formulate work plans and management systems and conduct periodic inspections of all electromagnetic flowmeters installed by users before the annual thunderstorm season.
2. Measure all grounding devices and meet safety requirements. If it is found that there is a great change in the value of the grounding resistance, the grounding system should be fully inspected, and if necessary, the grounding pile can be supplemented.
3. The length of the signal cable between the converter and the sensor can not be greater than 50M, and the signal cable must be put through the galvanized pipe. If the galvanized pipe is in the air, the galvanized pipe shall be reliably grounded with a wire, and the grounding resistance shall be less than 10.
4. The power supply is 220v unidirectional alternating current. Air switch is installed inside the meter box. The lightning arrester and the air switch are connected in parallel, and the wire is connected from the air switch to a three-outlet socket.
5. Check if there is any subsidence phenomenon in the soil around the grounding device.
6. External lightning protection (including lightning rods, lightning protection strips, deflectors, grounding electrodes, etc.) and internal lightning protection. Install suitable lightning protectors at the front end of the equipment that needs to be protected to form a conditional equipotential body between the equipment and the circuit. Both complement each other and are indispensable. The external lightning protection system protects the building body from lightning strikes, and the internal lightning protection is to prevent induction lightning and other forms of overvoltage from invading the device and causing damage. This is not guaranteed by external lightning protection.
7. The length of the arrester grounding wire cannot exceed 1M, and the cross-sectional area is larger than 6MM square stranded copper core insulated wire. If there is no ground network in the vicinity, a simple net should be made near the arrester. The method is as follows: Three flat steels or angle steels with a length of 1.5M are used to enter the ground in a regular triangle arrangement, and three flat steels are welded together with flat steel bars. In the corner, weld the bolt and connect the arrester ground wire.
The above is the measure of electromagnetic flowmeters for lightning protection in the summer. The solution is based on people's thinking. The problem is realistic. Different solutions need to be taken as different problems change, and lightning protection is an arduous and long-term task, and it is harmful. It is not small, so we must maintain a high degree of importance, even if the lightning protection measures have been done, but in the ordinary operation and maintenance, we must pay attention to the observation period during the lightning.