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Basic System Description
Inverter Mounting
and Installation
2–8
Basic System Description
A motor control system will obviously include a motor and inverter, as well as a breaker
or fuses for safety. If you are connecting a motor to the inverter on a test bench just to get
started, that’s all you may need for now. But a system can also have a variety of
additional components. Some can be for noise suppression, while others may enhance
the inverter’s braking performance. The figure and table below show a system with all
the optional components you may need in your finished application.
NOTE: Note that some components are required for regulatory agency compliance (see
Chapter 5 and Appendix D).
Thermal
switch
Breaker,
MCCB or
GFI
From power supply
Motor
L1 L2 L3
+1
+
Inverter
RB
GND
T1 T2 T3
Name Function
Breaker / discon-
nect
A molded-case circuit breaker (MCCB), ground fault
interrupter (GFI), or a fused disconnect device. NOTE:
The installer must refer to the NEC and local codes to
ensure safety and compliance.
Input-side
AC Reactor
This is useful in suppressing harmonics induced on the
power supply lines and for improving the power factor.
WARNING: Some applications must use an input-
side AC reactor to prevent inverter damage. See
Warning on next page.
Radio noise filter Electrical noise interference may occur on nearby
equipment such as a radio receiver. This magnetic
choke filter helps reduce radiated noise (can also be
used on output).
EMI filter (for
CE applications,
see Appendix D)
Reduces the conducted noise on the power supply
wiring between the inverter and the power distribution
system. Connect to the inverter primary (input side).
Radio noise filter
(use in non-CE
applications)
This capacitive filter reduces radiated noise from the
main power wires in the inverter input side.
DC link choke Suppresses harmonics generated by the inverter.
However, it will not protect the input diode bridge
rectifier.
Braking resistor This is useful for increasing the inverter’s control
torque for high duty-cycle (ON-OFF) applications, and
improving the decelerating capability.
Radio noise filter Electrical noise interference may occur on nearby
equipment such as a radio receiver. This magnetic
choke filter helps reduce radiated noise (can also be
used on input).
Output-side
AC reactor
This reactor reduces the vibrations in the motor caused
by the inverter’s switching waveforms, by smoothing
the waveform to approximate commercial power
quality. It is also useful to reduce harmonics when
wiring from the inverter to the motor is more than 10m
in length.
LCR filter Sine wave shaping filter for output side.