Appendix 2 Emi Protection - Chziri ZVF200-M User Manual

Appendix 2: EMI Prevention
Table 1:Inverter system EMI Prevention:
The electromagnetic environment is very complicated in industrial occasions.
Besides, the inverter's working principle also decides that EMI exists in
the inverter itself. So it is very important to solve EMC problems effectively
to ensure reliable running of the system in such a comprehens ive cond ition.
In this chapter, we give a research on EMC and provide correspondi ng
solutions to EMC, in hope of being helpful to you to solve practical problems.
(1) EMI Types and propagation mode
Type
.Common-base impedance coupling
Conducted interference A
.Common source impedance coupling
.Near field coupling
Radiated interference B
.Far field coupling
.Electric coupling
Inductive interference C
.Magnetic field induction
(2) Inverter System EMC Solutions
Power supply input cable
The distortion of power grid waveform caused by superimposed higher
harmonic current arisen out of nonlinear rectifier circuit to source impedance
may lead to interference over other electrical equi pment under the same
power grid. This kind of interference is named type A interference.
The power current and higher harmonic current brings in alternating
electromagnetic field around the circuit cable, which results in electric
field coupling and magnetic flux inductive coupling to the nearer parallel
cable such as the communication cable, small signal transmission cable
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Propagation mode
and etc. This kind of interference is named type C
Due to antenna effect of the cable's shielding layer, interference may be
produced over external wireless installation. This kind of interference is
named type B interference.
Propagation Diagram of Input Cable's Interference over External Equipment
Solutions:
This type of interference can be suppressed by installing an EMI power
supply filter or isolation transformer in the power supply input side.
This type of interference can be suppressed through well ordered wiring
or shieldin g. For example, the signal cable may adopt shielded wire and
the shielding layer shall be firmly grounded to reduce magnetic flux
inductive coupling and electric field coupling.The signal cable should
be at least 100mm away from the power cable. If the signal wire and the
power cable intersect, please intersect orthogonally. Generally speaking,
it is not advisory to use an overlong signal wire. If the operation instruction
is far from the inverter, then it is recommended to use an intermediate
relay to have a control over it, as shown in the figure below.
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or C interference.