Hitachi SJ100 Series Instruction Manual page 35

Inverter Input and Three-Phase Power
Heavy industrial machinery often needs the additional power available from higher
voltage/current sources, and from three-phase power. The Hitachi SJ100 Series of invert-
ers includes two sub-groups: the 200V class and the 400V class inverters. The drives
described in this manual may be used in either the United States or Europe, although the
exact voltage level for commercial power may be slightly different from country to
country. Accordingly, a 200V class inverter requires (nominal) 200 to 240VAC, and a
400V class inverter requires from 380 to 460VAC. Some 200V class inverters will accept
single-phase or three-phase power, but all 400V class inverters require a three-phase
power supply.
The common terminology for single phase power is Line (L) and Neutral (N). Three-
phase power connections are usually labeled Line 1 (L1), Line 2 (L2) and Line 2 (L3). In
any case, the power source should include an earth ground connection. That ground
connection will need to connect to the inverter chassis and to the motor frame (descrip-
tion given on page 2–16).
Inverter Output to the Motor
The AC motors also use three-phase power, but they
must connect only to the inverter's output terminals. The
output terminals are uniquely labeled (to differentiate
them from the input terminals) with the designations U/
T1, V/T2, and W/T3. This corresponds to typical motor
lead connection designations T1, T2, and T3. It is
generally not critical to connect a particular inverter
output to a particular motor lead for a new application.
The consequence of swapping any two of the three
connections is the reversal of the motor direction. For
safety reasons, you must connect the motor chassis
ground to the ground connection at the bottom of the inverter housing.
Notice the three connections to the motor do not include one marked "Neutral" or
"Return." The motor represents a balanced "Y" impedance to the inverter, so there is no
need for a separate return. In other words, each of the three "Hot" connections serves
also as a return for the other connections, because of their phase relationship.
The Hitachi inverter is a rugged and reliable device. The intention is for the inverter to
assume the role of switching power to the motor during all normal operations. Therefore,
this manual instructs you not to switch off power to the inverter while the motor is
running (unless it is an emergency stop). Also, do not install or use cut-off switches in
the wiring from the inverter to the motor (except thermal cut-off). Of course, safety-
related devices such as fuses must be in the design to break power during a malfunction.
SJ100 Inverter
3-Phase
AC Motor
V/T2
U/T1
Earth
GND
W/T3
1–9