【 Weak current College 】 audio system grounding

System grounded intent means real earth connection to provide a lightning discharge pathway, such as lightning rod end in the Earth, and later became on electrical equipment and power facilities provide leakage protection of discharge pathway of technical measures.

Audio system "and" zero signal reference point, also known as Earth point. In the audio system, this point must be a single, is not allowed to have a second or third point appears. Therefore, all devices of the system Earth point must summarize received a "point", this point is also called the "Star". "Star," the smaller the resistance of the better, and generally must be lower than 2 euro. The "Star" should be a sufficiently thick strands copper received the Earth looks, this is the signal ground.

1. the tasks of grounding system

Broadcast centre of grounding systems including audio (technology), grounding, HF earthing and grounding of computer system, phone, power, earthing and grounding lightning protection and earthing. Grounding system's mission is: to bypass the stray energy, making it the audio from the high sensitivity, high frequency appliances and computer equipment to transfer out, electric noise protection; prevention of electronic equipment for the instantaneous interference and disruption; protect the personal safety of the operator; prevent the building of lightning.

2. grounding category

The role of the grounding, divided into the following:

⑴ protective grounding

Protective earth is to prevent insulation damage equipment charged endanger personal safety of electrical equipment for shell with a strong connection between the protective device, it has grounded and zero. Protective earth was designed to make the device and the Earth have a low impedance of the current path to ensure personal safety and security of the facilities. Grounding is valid or not depends on the grounding resistance, resistance as small as possible. Grounding resistance earthing and grounding equipment, soil conditions, and environmental conditions and other factors. General requirements for the grounding resistance shall be in the following 10 euro.

Any high-voltage electrical equipment and electronic equipment of the enclosure, the base needs safety grounding to avoid direct contact with high voltage cabinets or avoid internal insulation damage causing leakage spark makes case for live, human touch shell you will get a shock.

Audio equipment it is best to use a separate good ground. Bad ground is neither safe nor easy to produce ground noise, not to the zero line 220V power and audio signals to the confusion. If these two points, as it makes sound system brings 50 week exchange acoustic interference.

Sometimes the device shell will Ma hands, this is due to AC leakage and device shell is not zero. Usually the power plug out of the swap out location then insert can be resolved.

⑵ overvoltage protective grounding

This is the setting for the lightning and the grounding protection device. Lightning protection system most widely used is the lightning and surge arrester. Lightning Rod reinforced through Tower or building into the ground, through the dedicated ground lightning arrester into the ground.
As I stand initially hotline Thunderstruck is caused because no arresters. Arrester thunderstorm season each year shall be tested prior to prevent failure.

⑶ shielding ground

To prevent electromagnetic induction and on audio cable shielded metal jacketing, electronic equipment, metal shell, shielding enclosures such as grounding of a protective measure. In all the Earth, the shield and the most complex, say, road unknown feeling. Because the screen itself can prevent outside interference, they may pass it on to outside interference, but in between all components in the equipment are also required to prevent electromagnetic interference.

Signal feeder of shield if you needto end the grounding, the grounding of optimally usually get signal transmission lines at the end of the Earth, and for balance and non-equilibrium ground between ports, the ground-it should choose one side of the balance. Be sure to prevent shielded wire ends of the Earth to form the ground loop, cause interference.

Shielding, grounding incorrectly can cause interference, such interference:

AC interference. This is mainly caused by AC power. Protection against AC interference, usually on the power supply for filtering or in power transformer of the initial stage and shielding and grounding. In large stray electromagnetic field, electromagnetic interference shielding to prevent grounding necessary.

High-frequency interference. This kind of interference from various wireless transmitter frequency or hyper-frequency signals, they are channeling into electronic device in the machine to get non-normal demodulation and audio interference forming.

⑷ signal ground

Signal grounding is between the systems and equipment, using low-impedance circuit for all kinds of wire to provide a common reference potential signal return path so that the ground wire of flowing through the circuit signal current do not affect each other.

With the purpose of protecting the Earth, signal grounding is primarily intended to dispel or other devices to this equipment. Circuits and equipment parts are connected to a common point, or potential equipotential surface to a common reference potential, so that all parts of the circuit are performing their normal function.

Since the Earth has a very large electric capacity, is the ideal zero potential. So whether or not to inject the Earth much current or charge, in the steady state is its potential to zero. In this way, the ideal grounding, namely the grounding impedance can in no time, the reference point of potential remains at zero potential. So in General, the Earth is to ensure that equipment and thegood connections of the Earth. But, broadly speaking, refers to the ground is not directly connected with the land, generally refers to a reference point for a good conductor of electricity.

Signal ground on the principle that same device signal input to signal output-end cannot join together and separately; the former level (equipment) to only output after the class (device) is connected to the input field. Otherwise, the signal may be formed through the ground, caused by noise and feedback. This equipment tests, signal connection with particular attention. For example, the same sound mixer, Tester shell grounding and the shell is not grounded, the indicator will be different. The grounding of the tester to float, this phenomenon.

Here to expand is signal ground. When all is setBy using the balance on the Earth, if any two devices online is equal to or two to spare, you can have only one thread at both ends of the Earth, the remaining signal lines can be single ground. As shown in the figure below.

There's only 1 line at both ends of the Earth is (shield) and the devices connected to the line 2 only in the input-side shield ground, output is suspended. For example, a mixer and effects between may have 4 lines, this case can only have one line at both ends of the Earth (for card Lennon's head, the Earth is "1" feet and shielding layer welded together, vacant is not welded), and the remaining three are in the input-side grounding. If multiple lines at both ends of the Earth, the Earth between the big loop, when the external electromagnetic interference (such as phone), produces the induced current, introducing noise, if only one line, at both ends of the earth does not form a loop.