Basic System Description - Hitachi SJ7002 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 /
disconnect
Input side
AC Reactor
Radio noise filter Electrical noise interference may occur on nearby
EMI filter (for
CE applications,
see Appendix D)
T
Radio noise filter
PD(+1)
(use in non-CE
applications)
DC link choke
P(+)
RB
Braking resistor
N(–)
Braking unit
GND
Radio noise filter Electrical noise interference may occur on nearby
W
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.
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. A DCL reactor is required for
models -185xxx to -4000xxx
Braking components are useful for increasing the
inverter's control torque for high duty-cycle (ON-
OFF) applications, and improving the decelerating
capability.
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 commer-
cial 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. The LCR
filter is not required for models -1850xxx to -
4000xxx.
SJ700 Inverter
2
Function
2–5