EM11 User’s Manual
3. Installation of Frequency Inverter
19
3.3 Peripheral Devices Connection Diagram
Diagram 3-2 Peripheral Devices Connection
3. Installation of Frequency Inverter
EM11 User’s Manual
20
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 100meters, 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.
