3. Installation of Frequency Inverter
EM12 User’s Manual
18
3.4 Instructions of Main Circuit Peripheral Devices
Table 3-1 Main circuit peripheral devices use instructions
Parts Name
Installation Location
Function Description
MCCB
Front of input circuit
The capacity of the circuit breaker shall be 1.5 to 2 times of the rated
current of the inverter.
The protect time of the circuit breaker shall fully consider the time
features of the inverter overload protection.
Residual-current
circuit breaker
(RCCB)
Front of input circuit
As the inverter output is the high-frequency pulse output, there will be
high-frequency leakage current. Special leakage circuit breaker shall
be used when installing leakage circuit breaker at the input side of the
inverter.
It is suggested that B type leakage circuit breaker be used, and the
leakage current value shall be set as 300mA.
Contactor
Between MCCB and
frequency inverter
input side
Frequently open and close of contactor will cause inverter failure, so
the highest frequency for opening and closing of contactor shall be not
exceeded than 10 times/min when braking resistor is used, to avoid the
over-hot damage of the braking resistor, thermal protection relay with
braking resistor over-hot detection shall be installed, by terminal of the
thermal protection relay to disconnect the contactor.
Input AC
reactor or DC
reactor
Frequency inverter
input side / near the
frequency inverter
The inverter power supply capacity is more than 600kVA or 10 times
of the inverter capacity.
If there is switch type reactive-load compensation capacitor or load
with silicon control at the same power node, there will be high peak
current flowing into input power circuit, causing the damage of the
rectifier components.
When the voltage unbalancedness of the three-phase power supply of
the inverter exceeds 3%, the rectifier component will be damaged.
It is required that the input power factor of the inverter shall be higher
than 90%.
When the above situations occurred, install the AC reactor at the input
side of the inverter or DC reactor to the DC reactor terminal.
Input noise filter
The frequency inverter
input side
To reduce the noise input from the power to the inverter or output from
the inverter to the power.
Thermal
protection relay
The output side of
frequency inverter
Although the inverter has motor overload protection function, when
one inverter drives two or more motors or multi-pole motors, to
prevent the motor over-temperature failure, thermal protection relay
shall be installed between the inverter and each motor.
Output filter
The output side of
frequency inverter
When the output side of the inverter is connected with output filter, the
conduction and radiation interference can be reduced.
Output AC
reactor
Between the output
side of frequency
inverter and motor,
near the frequency
inverter
When the cable connecting the inverter and the motor is longer than 50
meters, it is suggested to install AC output reactor to suppress the
high-frequency oscillation to avoid the damage to motor insulation,
large leakage current and frequent inverter protective action.
Summary of Contents for EM12 Series
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