Basic System Description - Hitachi SJ300 Series Instruction Manual

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 perfor-
mance. The figure and table below show a system with all the optional components you may
need in your finished application.
Power source
L1 L2
Breaker,
MCCB or
GFI
R S
Inverter
R0
T0
U V
T1 T2
Motor
Thermal switch
NOTE: Some components are required for regulatory agency compliance (see Chapter 5 and
Appendix D).
L3
Breaker / discon-
nect
Input side
AC Reactor
Radio noise filter
EMI filter (for CE
applications, see
T
Appendix D)
PD(+1)
Radio noise filter
(use in non-CE
P(+)
applications)
DC link choke
RB
Braking resistor
N(–)
Braking unit
GND
W
Radio noise filter
Output side
AC reactor
T3
LCR filter
Name
A molded-case circuit breaker (MCCB), ground
fault interrupter breaker (GFI), or a fused
disconnect device. NOTE: The installer must
refer to the NEC and local codes to ensure safety
and compliance.
This is useful in suppressing harmonics induced
on the power supply lines, or when the main
power voltage imbalance exceeds 3% (and
power source capacity is more than 500 kVA), or
to smooth out line fluctuations. It also improves
the power factor.
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).
This filter reduces the conducted noise in the
power supply wiring between the inverter and
the power distribution system. Connect it to the
inverter primary (input side).
This capacitive filter reduces radiated noise from
the main power wires in the inverter input side.
The choke suppresses harmonics generated by
the inverter. However, it will not protect the
input diode bridge rectifier.
Braking components are useful for increasing
the inverter's control torque for high duty-cycle
(ON-OFF) applications, and improving the
decelerating capability.
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 at input).
This reactor reduces the vibrations in the motor
caused by the inverter's switching waveform, 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.
Sine wave shaping filter for output side.
SJ300 Inverter
Function
2–5