2.3 Cable Wiring
Complete the cable connections by connecting an appropriately rated cable to the terminals on the
power and control terminal blocks. Read the following information carefully and follow all warning
instructions.
Do not connect power to the inverter until installation has been fully completed and the inverter is
ready to be operated.
Power supply wiring must be connected to the R, S, and T terminals. Arrangement of the input phase
sequence is not necessary. Connecting power supply cables to other terminals will cause internal
damage to the inverter.
Motor cables must be connected to the U, V, and W Terminals. Arrangement of the output phase
sequence will affect motor rotation direction.
Ground cables must be connected to the designated ground terminals. Do not connect ground wires to
the DC bus negative bus (N-) terminal.
Use cables with the largest possible cross-sectional area to ensure that voltage drop is minimized over
long cable runs. Lowering the carrier frequency or installing a micro surge filter will also help reduce
voltage drop.
Use copper cables rated at 600 V, 75 ° for the power terminal wiring.
Use copper cables rated at 300 V, 75 ° for the control terminal wiring
Voltage drop is calculated with the following formula.
Apply rated torques to the terminal screws. Loose screws cause heated connections and can lead to
short circuits and malfunctions. Tightening the screws too much may damage the terminals.
The inverter’s power terminal connections can cause harmonics that may interfere with other
communication devices located near to the inverter. To reduce interference the installation of noise
filters or line filters may be required.
Long cable runs can cause reduced motor torque in low frequency applications due to voltage
drop. Long cable runs also increase the circuits susceptibility to stray capacitance and may
trigger over current protection within the inverter or result in malfunction of equipment
connected to the inverter.
Motor Cable Length:
• 7.5 HP → 800 HP-----492 ft. (150 m).
To increase the service life of the motor and the inverter, Benshaw recommends adding an
output reactor with motor lead lengths up to 100 ft. For motor lead lengths between 100 ft. up
to 1500 ft., install a Long Lead (dV/dT) filter.
To avoid circuit interruption or damaging connected equipment, do not install PFCC’s, surge
protection or EMC filters on the output side of the inverter.
When connecting a contactor to the output of the inverter, avoid ON / OFF contactor operation while
inverter is running. It may cause the inverter to trip or short circuit the output of the inverter.
Route signal cables away from power cables to avoid interference.
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