Problems with noise meters and grounding
Ground and electricity (signals), which are inseparable twins. Grounding, usually means connecting a conductor to the earth. Can be in the electronics of the ground, may have nothing to do with the earth, it is only a circuit in the first potential surface. For example, the ground in a radio or television set is only a potential reference point in the receiver circuit. Grounding, in power and electronic technology, both simple and complex, but also essential. According to the role of grounding, can be divided into work grounding, protective grounding, overvoltage protection grounding, anti-static grounding, shielding ground, signal ground and so on. In radio and television technology, the above several grounding types are encountered. Now combined with the actual on certain grounding technology issues to make a statement.
One. Protective grounding protective grounding is to prevent insulation damage caused by the equipment charged and endangered people ** and set up a protective device, it has two ways to ground and zero. According to the power regulations, where the three-phase four-wire power supply system, due to the neutral grounding, so should be used in a zero way, and the metal casing of the equipment through the conductor to the zero line, and does not allow the equipment shell directly grounded. This is particularly common in the switchgear in the distribution room of the broadcasting system, power switchgear such as central air-conditioning units, transmitters and other power-consuming equipment. When planning and designing, an earth bus should be drawn from the ground network to each piece of equipment, and then the machine casing should be connected to the earth bus with a conductor. It is worth pointing out: the grounding wire should be connected to the equipment's grounding special terminal, the other end * preferably using welding. Sometimes the equipment shell will be numb hands, this is due to AC leakage and the equipment shell is not caused by zero connection. Generally can be pulled out of the power plug to change the position and then inserted can be resolved. This is often moved in some of the recording equipment, because the zero line is often ignored, the operator may have both hands at the same time contact with zero and not zero equipment, it is possible to occur the above phenomenon.
Two. Overvoltage protection grounding This is a grounding protection device for lightning protection. Lightning protection devices* widely used are lightning rods and lightning arresters. Lightning rod through the tower or building steel into the ground, lightning arrester through the special ground into the ground. Lightning arresters are inspected annually before the thunderstorm season to prevent failure. For example, the lightning strike on the station's ** telephone access device was caused by the failure of the lightning arrester on the telephone line. In the lightning protection lead line, never connect other equipment ground, lightning protection lead line can only be directly into the ground alone, otherwise the lightning will be through the lead line damage to other equipment. Such as a satellite TV receiver has been struck by lightning several times, the original problem is the feeder and roof metal fence friction and insulation damage, and metal fence and lightning rod lead down body welded together, so that lightning into the bad receiver.
