Fuling Inverter DZB200 Series User Manual page 11

DZB Series
Note: Pay attention to the polarity of the diode as shown in the figure 3-8. Otherwise if the digital
output terminal has output, the DC24V power supply will be damaged.
DZB300
EV
MO1
MCM
Fig. 3 -8 Digital Input Terminal of DZB Series Inverter
6. EMC Issues
6 1 Influence of Harmonics .
1) The high frequency harmonics of mains supply will influence the rectifying circuit of the inverter.
The harmonics will heat the rectifying circuit and even damage the circuit. So, it is recommended to
install the filtering device in the envir onment where the power quality is poor.
2) Since the inverte r output has high frequency harmoni cs, the output cannot be installed with
capacitor or surge suppressing devices because the capacitor and surge suppressing device may
resonate the circuit and damage the equipment.
6.2 EMI
1) Two kinds of EMI, one is the EMI a round the inverter and disturbs the inverter. This kind of EMI is
weak, besides the inverter has been designed with strong immunity. Another is the EMI from the
inverter that may influence the equipment around the inverter. The inverter itself is a disturba nce
source because it outputs PWM wave through high carri er frequency, so solving the EMI issue is
mainly to reduce the EMI of inverter.
Methods:
A) Inverter and other equipment shall be well grounded and the grounding resistance shall be less than
5ohm.
B) Inverter's power cables shall be vertical instead of parallel with the control cables.
C) For the application with strong disturbance, the powe r cables from the motor to the inverter shall be
shielded and the shielding layer shall be grounded.
D) The cables of disturbed equipment shall be twisted shielded cables and the shielding layer shall be
grounded.
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Cha pter 3 Mechanical and Electrical Installation
Diode
Relay
DZB Series
2) Reducing the disturbance to the inverter from other equipment
The re lay, contactor or electronic -magnetic braking device will disturb t he invert er.
Take the following act ions to solve this issue:
A) Install surge suppressing devices to the disturbing de vice
B) Install filter to the input of t he inverter
C) Inverter's c ontrol cables shall be shie lded and the shielding layer shall be grounded
3) Method to reduce the disturbance from the inverter to the equipment
Two kinds of noises, one is the radiation from the inverte r itself, and another is the radiation from the
cable between the inverter and the motor. These two kinds of radiations induce the cables of the
equipment and make the equipment work abnormally. Following method can be used:
A) If t he measuring meters, radio equipment and sensors and their signal cables are install ed in a
cabinet together with t he drive , these equipment cables will be easily dist urbed. Take the actions
below to solve the problem: The equipment and the signal cables should be as far away from the
inverter as possible; Signal cables and power cables shall not be routed in parallel or bound togethe r;
The signal and power cables should be shielded; Install r adio noise filter and linea r noise filter at
the input and output sides of the inverter
B) If the exter nal equipment shares a sa me AC supply wi th the inverter, and the above cannot eliminate
the disturbance, then t he user should install a linear filter or a radio noise filter.
C) Ground the external equipment and e liminate the disturbance of the leakage current from the
inverter's grounding ca ble.
6.3 Le akage current
The inverter has two kinds of leakage current, one is the grounding leakage current and another is the
leakage current between the lines:
1) Grounding leakage current:
The distributed capaci tance exists betw een the cables and the ground, and the bigger the c apacitance
and the bigger the leakage current, so the motor cables should be as short as possible. Besi des, the
bigge r the carrier frequency is, the bigger the leakage current is, so the user can al so reduc e the carrier
wave frequenc y, but the motor noise may increase. Insta lling rea ctor can also reduce the leakage current.
The leakage current is increased with the increase of the circuit current, so the lea kage current is big if
the motor power is big.
2) Lea kage current bet ween lines:
The distributed capaci tance exists in the inverter抯 output cable s, and resonance may occur if high
frequency harmonics e xist in the current, thus the leakage current occurs, which may result in the wrong
action of relay.
The method to solve this issue is to reduce the carrier fre quency or install the output reactor. It is
recommended to use inverter抯 protection func tion instead of a thermal relay to protect the motor before
using the inverter.
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Chapter 3 Mechanical and Electric al Installation
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