User Manual
EM100 Mini Inverter
109
3.
The control signal cable and the detection line of the inverter employ shielded cable or
twisted-pair cable, and the shielding layer shall be grounded reliably.
8.3.5 Handling the EMI of the Inverter on the Peripherals
These interferences include two types: one is radiation interference of the inverter, and the
other is conduction interference of the inverter. Refer to the following methods for handling
different interferences:
1.
For the measuring meters, receivers and sensors, their signals are generally weak. If they
are placed nearby the inverter or together with the inverter in the same control cabinet,
they are easy to encounter interference and thus malfunctions are generate. The
following methods are recommended
z
Put in places far away from the interference source
z
Do not arrange the signal cables with the power cables in parallel and never bind them
together.
z
Both the signal cables and power cables employ shielded cables and are well earthed.
z
Install ferrite magnetic ring for the power cable (nickel-zinc ring with suppressing
frequency> 30MHz) at the output side of the inverter and wind it 2 to 3 cycles.
z
Install EMC output filter in more severe conditions.
2.
When the devices interfered and the inverter shall the same power supply, it may cause
conduction interference. Install EMC input filter between the inverter and the power
supply. Refer to 8.3.7 for specific operation procedures).
3.
The peripherals are separately grounded which can lower common-mode interference
caused by common-ground impedance.
8.3.6 Leakage Current and Handling
Distributed capacitance exists in power cable and the earth. The longer the power cable is
and the bigger distributed capacitance to the earth is, and the bigger the leakage current is.
The higher the carrier frequency is, and the bigger the leakage current is. Reduce leakage
current by shortening power cable and lowering carrier frequency.
8.3.7 Precautions for Installing EMC Filter at the Input of Power Supply
1.
Since the filter belongs to Classification I electric appliances, the metal housing of the
filter shall be well connected to the metal ground of the installing cabinet. It is required
to have good conduction continuity. Otherwise, there may be danger of electric shock
and the EMC effect may be greatly affected.
2.
Through the EMC test, it is found that the filter ground must be connected with the PE
end of the inverter at the same common earth. Otherwise the EMC effect may be greatly
affected.
3.
The filter shall be installed at a place as close as possible to the input of the power supply,
and the input cable of filter power supply shall be as short as possible in the control
cabinet.
4.
If the input and output lines of the filter is too close, the HF interference will by-pass the
filter, and couple the input and output lines of the filter directly. The power supply filter
will be functionless.
5.
Typically there is a special grounding terminal on the filter housing. However, if the
filter is connected to the control cabinet housing with a wire, it cannot prevent HF
interference. It is because the long cable has big HF impedance, the filter would not play
a role as a bypassing device. The correct installation method is to connect a large area of
the filter housing to the conductive plane of the metal housing, clear the insulating paint
to ensure a reliable connection.
