The necessity of the noise filter for power equipment
As the power adapter is varied, the use of the noise filter also have various types. Have the following reasons for using the noise filter in power equipment.
1, to prevent extraneous noise and make the control circuit of power supply equipment itself to misoperation.
2, to prevent the received power supply equipment malfunction due to noise.
Noise suppression of power generated by the equipment, 3.
4, the inhibition produced by the device after noise power equipment communication.
Power supply device, in addition to outside its internal drive circuit, and protection circuit, a program circuit, input and output level detection circuit, circuit very complicated. The circuit is mainly composed of a special or general power integrated circuits. The effective way of these circuits due to external noise caused misoperation prevent is using the noise filter.
On the other hand, the noise from entering the power equipment input, it can appear in the output of. It induced voltage in the equipment circuit, become the cause of false action. It also can be used to prevent noise filter. Terminal noise and interference radiation so-called problem, power supply equipment itself as clock frequency switch in the switch action and equipment, there will be noise in the power supply terminal equipment input, interference radiation. They interfere with other equipment, so we must take effective measures. Recently, countries the implementation of the noise limit rules. The United States has FCC, Germany FTZ noise rules, if you do not meet the specifications of products could not be sold. For this reason, the power equipment must use the noise filter.
Common mode noise and normal noise
In the dissemination of the noise is of two kinds: common mode noise and normal noise. Common mode noise current flowing into the earth, normal noise is the current online between flow. In taking noise countermeasures, mainly on account of the more common mode noise. However, in the low frequency range, with a large proportion of the normal transmission noise. So we must choose the appropriate noise filter according to the noise component.
Types of noise filter for power supply equipment
Uninterruptible power supply device using the noise filter according to the shape can be divided into box type and scattered type. Cassette can also be said to be integrated, is to coil, capacitor assembly in metal or resin shell form. Distributed, is usually installed title line filter on a printed board consists of capacitance state coil or winding device, constitutes a form of noise filter. Exactly which one to use according to the cost, the installation space, characteristic to decide.