CHF100A series high performance universal inverter
.24.
Three necessary conditions or essentials of electromagnetic interference are:
interference source, transmission channel and sensitive receiver. For customers, the
solution of EMC problem is mainly in transmission channel because of the device
attribute of disturbance source and receiver can not be changed.
4.6.2 EMC features of inverter
Like other electric or electronic devices, inverter is not only an electromagnetic
interference source but also an electromagnetic receiver. The operating principle of
inverter determines that it can produce certain electromagnetic interference noise. At the
same time inverter should be designed with certain anti-jamming ability to ensure the
smooth working in certain electromagnetic environment. Following is its EMC features:
4.6.2.1 Input current is non-sine wave. The input current includes large amount of
high-harmonic waves that can cause electromagnetic interference, decrease the grid
power factor and increase the line loss.
4.6.2.2 Output voltage is high frequency PMW wave, which can increase the
temperature rise and shorten the life of motor. And the leakage current will also increase,
which can lead to the leakage protection device malfunction and generate strong
electromagnetic interference to influence the reliability of other electric devices.
4.6.2.3 As the electromagnetic receiver, too strong interference will damage the inverter
and influence the normal using of customers.
4.6.2.4 In the system, EMS and EMI of inverter coexist. Decrease the EMI of inverter can
increase its EMS ability.
4.6.3 EMC Installation Guideline
In order to ensure all electric devices in the same system to work smoothly, this section,
based on EMC features of inverter, introduces EMC installation process in several
aspects of application (noise control, site wiring, grounding, leakage current and power
supply filter). The good effective of EMC will depend on the good effective of all of these
five aspects.
4.6.3.1 Noise control
All the connections to the control terminals must use shielded wire. And the shield layer
of the wire must ground near the wire entrance of inverter. The ground mode is 360
degree annular connection formed by cable clips. It is strictly prohibitive to connect the
twisted shielding layer to the ground of inverter, which greatly decreases or loses the
shielding effect.
Connect inverter and motor with the shielded wire or the separated cable tray. One side
of shield layer of shielded wire or metal cover of separated cable tray should connect to
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