Issues of Sound Level Meters and Grounding
Earth and electricity (signals) are inseparable twins. Grounding usually refers to connecting a conductor to the earth. In electronic technology, the ground may have nothing to do with the earth, it is just an equipotential surface in the circuit. Like the ground in a radio or television, it is just a potential reference point in the receiver circuit. Grounding, in power and electronic technology, is both simple and complex, and essential. According to the function of grounding, it can be divided into various types such as working grounding, protective grounding, overvoltage protective grounding, anti-static grounding, shielding grounding, signal grounding, etc. In broadcasting technology, the above types of grounding will be encountered. Now let's elaborate on some grounding technology issues based on practical experience.
One. Protective grounding is a protective device set up to prevent insulation damage from causing live equipment and endangering personal safety. It has two methods: grounding and neutral grounding. According to power regulations, for systems that use three-phase four wire power supply, due to the neutral line being grounded, a neutral connection method should be used. The metal casing of the equipment should be connected to the neutral line through a conductor, and direct grounding of the equipment casing is not allowed. This is particularly common in switch devices in the distribution room of the broadcasting and television system, power switch devices such as central air conditioning units and transmitters, and large power consuming equipment. When planning and designing, the grounding bus should be led out from the grounding grid to each equipment, and then the machine casing should be connected to the grounding bus with a conductor. It is worth noting that the grounding wire should be connected to the dedicated grounding terminal of the equipment, and the other end should be welded. Sometimes the device casing may feel numb, which is caused by AC leakage and the device casing not being grounded. Generally, the problem can be solved by unplugging and swapping the power plug before inserting it. In some frequently moving cataloging devices, the neutral wire is often ignored, and some operators may touch both neutral and non neutral devices with both hands, which may lead to the above phenomenon.
Two. Overvoltage protection grounding is a grounding protection device designed to prevent lightning strikes. The widely used lightning protection devices are lightning rods and lightning arresters. The lightning rod is grounded through the steel bars of the iron tower or building, while the lightning arrester is grounded through a dedicated ground wire. Lightning arresters must be inspected before the thunderstorm season every year to prevent failure. If my telephone access device is struck by lightning, it is due to the failure of the lightning protection device on the telephone line. Never connect the grounding wire of other devices to the lightning protection down conductor. The lightning protection down conductor can only be directly grounded separately, otherwise lightning will damage other devices through the down conductor. If a certain satellite TV receiver has been struck by lightning several times, the original cause was insulation damage caused by friction between the feeder and the metal guardrail on the roof, and the metal guardrail was welded to the lower body of the lightning rod, resulting in lightning entering and damaging the receiver.
