Chapter 4 Electrical Installation
Shenzhen Hpmont Technology Co., Ltd
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HD20 Series Inverters User Manual
4.5.6 Conduction, Radiation and Radio Frequency Interference
Countermeasures
EMI of the inverter
The inverter’s operating theory means that some EMI is unavoidable. The inverter is usually
installed in a metal cabinet which normally little affects the instruments outside the metal cabinet.
The cables are the main EMI source. If connect the cables according to this manual, the EMI can
be suppressed effectively.
If the inverter and other control equipment are installed in one cabinet, the area rule must be
observed. Pay attention to the isolation between different areas, cable layout and shielding.
Reducing conducted interference
Please add a noise filter to suppress conducted interference on the output side. Additionally,
conducted interference can be efficiently reduced by threading all the output cables through a
grounded metal tube. And conducted interference can be dramatically decreased when the
distance between the output cables and the signal cables is above 0.3m.
RF interference clearing
The I/O cables and the inverter produce radio frequency interference. A noise filter can be
installed both on the input side and output side, and shield them with iron utensil to reduce RF
interference. The wiring distance between the inverter and the motor should be as short as
possible shown in Figure 4-21.
Figure 4-21 RF interference clearing
4.5.7 Input and Output Reactor
AC input reactor
The purpose of installing an AC input reactor is: to increase the input power factor; to dramatically
reduce the harmonics on the input side at the high voltage point of common coupling and prevent
input current unbalance which can be caused by the phase-to-phase unbalance of the power
supply. An AC line reactor which will help to protect the input rectifiers also reduces external line
voltage spikes (for example the lightning!).
AC output reactor
Generally speaking, when the length of the cable between inverter and motor is more than 100m,
it will cause leakage current and inverter tripping. It suggests that the user should consider
installing an AC output reactor.
HD20
EMI filter
X
X
X
MCCB
M
Iron box
Metal tube
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EMI filter