Time： 2019-02-28 16:30:27
Introduction to Basic Knowledge of Filters
--Our EMI filter are designed on the basis of IEC939-1、IEC939-2、EN13300、EN133200 and UL1283、
GB/T15287-1994、GB/T15288-1994 Standards. Our filter are the low-pass filter composed by the passive components
(L、C、R)and adopt the impedance mismatch theory between filter and access port.
General circuit configuration
Customers choose their own devices in the power filter, the device should be based on their actual
interference situation combined with power filter works to choose. Mains filter works by using an impedance mismatch
at both ends of the principle to work, so customers in the choice of power supply filter should refer to the principles of
the Fig.1, the only way to maximize the power supply filter filtering effect, to meet your requirements.
* △FILTER: 3 phase power system without a Neutral phase is referred to as a △ filter.
* Y FILTER: 3 phase power system have a Neutral line called Y filter .
Single-phase leakage-current measurement circuits
Filter internded for connection to a 2 wire power supply
Filter intended for connection to a 3 wire power supply，ground neutral power supply
Three-phase leakage-current measurement circuit
The insertion loss is measured according to CISPR 17. In most cases, published insertion loss data assumes that
power line and load have the same impedance and all such data are in practice generated form 50Ω test system.
The best way to verity actual effectiveness in noise suppression is to mount the filter in the equipment to test the
conducted emission in a shield room.
Insertion loss is composed of common mode and differential mode insertion loss, and the test measurement circuit:
Common mode Differention mode