Summer is the rainy season, and it often rains and thunders. The lightning is with a strong current. Among the accessories of the electromagnetic flowmeter, once the lightning strikes the conduction device, the strong current enters the converter and will burn the converter and the power supply. Seriously or even the main control board, the lightning Generally it is the nemesis of electronic products, so general electronic products or equipment with electronic components need lightning protection, so how to prevent lightning in summer?
First of all, the meaning of lightning protection is to prevent it, so since it is prevention, it must be reflected in the installation, that is, lightning protection must be considered when installing the electromagnetic flowmeter.
Harm caused by lightning to electromagnetic flowmeter:
1. Lightning invades and burns the meter through the power supply.
2. At the same time when the lightning is generated, the electronic components of the powerful magnetic field instrument generate magnetic induction, and instantaneously generate strong voltage and current, which breaks down the insulation and burns the instrument.
3. Lightning pulse waves invade the flow meter through the wireless network and burn out the communication chip or instrument.
There are 7 following lightning protection notes:
1. Formulate work plans and management systems, and conduct regular inspections of electromagnetic flowmeters installed by all users before the thunderstorm season each year.
2. Measure all grounding devices and meet the safety requirements. If it is found that the grounding resistance value is greatly changed, the grounding system should be thoroughly inspected, and grounding piles can be repaired if necessary.
3. The length of the signal cable between the converter and the sensor cannot be greater than 50M, and the signal cable must be sheathed with a galvanized tube. If the galvanized pipe is in the air, the galvanized pipe should be reliably grounded with a wire, and the grounding resistance is less than 10.
4. The power supply is 220v unidirectional alternating current. An air switch is installed in the instrument box. The lightning arrester and the air switch are connected in parallel. The wire comes out of the air switch and is connected to a three-phase socket.
5. Check whether the soil around the grounding device is sinking.
6. External lightning protection (including lightning rod, lightning protection belt, down conductor, grounding electrode, etc.) and internal lightning protection. Install a suitable lightning protector at the front end of the equipment that needs to be protected, so that the equipment, line and ground form a conditional equipotential body. The two complement each other and are indispensable. The external lightning protection system protects the building body from lightning strikes, while the internal lightning protection is to prevent induced lightning and other forms of overvoltage from invading the equipment to cause damage, which cannot be guaranteed by external lightning protection.
7. The length of the grounding wire of the lightning arrester cannot exceed 1M, and the cross-sectional area is more than 6 square mm. If there is no ground net nearby, a simple ground net should be made near the arrester. The method is as follows: use three flat bars or angle bars with a length of 1.5 meters, into the ground in a regular triangle arrangement, and use the flat steel bars to weld the three flat bars , Weld bolts at one corner, and then connect the grounding wire of the arrester to install the panel on the ground plane of the 220VAC grounding wire.
The above are the measures and attention of the electromagnetic flowmeter in the summer for lightning protection. The method is human thought, the problem is realistic, and different solutions need to be adopted as different problems change, and lightning protection is a difficult and long-term task. And the harm is not small, so we must maintain a high degree of attention, even if the lightning protection measures have been completed, but in normal operation and maintenance, we must pay attention to the observation work during lightning.
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Post time: 21-09-21