Hitachi SJ7002 Series Instruction Manual page 184

4–22
Using Intelligent Input Terminals
Commercial
Power Source
Enable
14
Opt. Code
[CS]
Symbol
Valid for
[1] to [8]
Inputs
Required
B003, B007
Settings
Default
Requires
terminal config.
Power source, 3-phase
MCCB
L1
L2
L3
• When the Run command is active immediately after the power is turned ON, a USP error
will occur. When this function is used, wait for at least three (3) seconds after powerup
before applying a Run command.
The commercial power source switching function is useful in systems with excessive starting
torque requirements. This feature permits the motor to be started "across the line," sometimes
called a bypass configuration. After the motor is running, the inverter takes over to control the
speed. This feature can eliminate the need to oversize the inverter, reducing cost. However,
additional hardware such as magnetic contactors will be required to realize this function. For
example, a system may require 55KW to start, but only 15KW to run at constant speed. There-
fore, a 15KW rated inverter would be sufficient when using the commercial power source
switching.
The [CS] Commercial Power Source Enable input signal operation is as follows:
• OFF-to-ON transition signals the inverter that the motor is already running at powerup (via
bypass), thus suppressing the inverter's motor output in Run Mode.
• ON-to-OFF transition signals the inverter to apply a time delay (B003), frequency match its
output to existing motor speed, and resume normal Run Mode operation
The following block diagram shows an inverter system with bypass capability. When starting
the motor directly across the line, relay contacts Mg2 are closed, and Mg1 and Mg3 are open.
This is the bypass configuration, since the inverter is isolated from the power source and motor.
Then Mg1 contacts close about 0.5 to 1 second after that, supplying power to the inverter.
Mg2
GFI
Mg1
Mg3
R
U
SJ700
2
S V
T W
R0
T0
AL1
FW
[RV]
AL0
[CS]
AL2
CM1
H
O
L
Thermal
switch
Motor