Noise characteristics of power supply equipment
Sep 07, 2018| Necessity of noise filter for power supply equipment
Just as power adapters are versatile, there are various types of noise waves that are used. There are the following reasons for using a noise filter in a power supply unit.
1. Prevent malfunction of the control circuit of the power supply device due to external noise.
2. Prevent equipment that receives power supply from malfunctioning due to noise.
3. Suppress the noise generated by the power supply equipment.
4. Suppresses noise generated by the device and transmitted through the power device.
The power supply device has a protection circuit, a program circuit, an input/output level detection circuit, and the like in addition to the drive circuit, and the circuit is quite complicated. These circuits are primarily comprised of dedicated or general purpose power supply integrated circuits. An effective way to prevent these circuits from malfunctioning due to external noise is to use a noise filter.
On the other hand, a fraction of the noise entering from the input of the power supply device can appear at the output. It generates an induced voltage in the circuit of the device, which causes a malfunction. This can also be prevented with a noise filter. The so-called terminal noise and interference radiation problems, the power supply device itself in the switching action and when the device is clocked, there will be terminal noise at the input end of the power supply device, generating interference radiation. They all interfere with other devices, so you must take strong measures. Recently, the Ministry of Nationalities has implemented noise restriction rules. There are FCCs in the United States and FTZ and other noise rules in Germany. If the specifications are not met, the products cannot be sold. For this reason, the power supply must use a noise filter.
Type of noise filter for power supply equipment
The noise filters used in uninterruptible power supply devices can be divided into box type and distributed type according to the shape. The cassette can also be said to be an integrated type, which is a form in which a coil, a capacitor, or the like is assembled in a metal or resin case. Decentralized, usually a common-state coil or line capacitor with a nominal line filter mounted on a printed board, forming the form of a noise filter. Which one to use depends on cost, installation space, characteristics, and so on.