2-17
Grounding terminals ( G)
Be sure to ground either of the two grounding terminals for safety and noise reduction. The inverter is designed
to use with a safety grounding to avoid electric shock, fire and other disasters.
Grounding terminals should be grounded as follows:
1) Ground the inverter in compliance with the national or local electric code.
2) Use a thick grounding wire with a large surface area and keep the wiring length as short as possible.
Main circuit power terminals (L1/R, L2/S, L3/T)
1) Connect these terminals to the power supply via a molded-case circuit breaker or ground-leakage circuit
breaker for circuit protection. Phase-sequence matching is unnecessary.
2) To insure safety, a magnetic contactor should be used to disconnect the drive from the power supply when
the drive protective function activates.
3) Use control circuit terminal FWD/REV or the RUN/STOP key on the keypad panel to start or stop the drive.
The main circuit power should be used to start or stop the drive only if absolutely necessary and then
should not be used more than once every hour.
4) If you need to connect these terminals to a single-phase power supply, please contact the factory.
Drive output terminals (U, V, W)
1) Connect these terminals to a 3-phase motor in the correct phase sequence. If the direction of motor rotation
is incorrect, exchange any two of the U, V, and W phases.
2) Do not connect a power factor correction capacitor or surge absorber to the drive output.
3) If the cable from the drive to the motor is very long, a high-frequency current may be generated by stray
capacitance between the cables and result in an overcurrent trip of the drive, an increase in leakage current,
or a reduction in current indication precision.
When a motor is driven by a PWM-type drive, the motor terminals may be subject to surge voltage generated by
drive element switching. If the motor cable (with 460V series motors, in particular) is particularly long, surge
voltage will deteriorate motor insulation. To prevent this, use the following guidelines:
Drives 7.5 HP and larger
Motor Insulation Level 1000V 1300V 1600V
460 VAC Input Voltage 66 ft (20 m) 328 ft (100 m) 1312 ft (400 m) *
208 VAC Input Voltage 1312 ft (400 m) * 1312 ft (400 m) * 1312 ft (400 m) *
Drives 5 HP and smaller
Motor Insulation Level 1000V 1300V 1600V
460 VAC Input Voltage 66 ft (20 m) 165 ft (50 m) * 165 ft (50 m) *
208 VAC Input Voltage 328 ft (100 m) * 328 ft (100 m) * 328 ft (100 m) *
* For this case the cable length is determined by secondary effects and not voltage spiking.
When a motor protective thermal O/L relay is inserted between the drive and the motor, the thermal
O/L relay may malfunction (particularly in the 460V series), even when the cable length is 165 feet
(50m) or less. To correct, insert a filter or reduce the carrier frequency. (Use function code “F26
Motor sound”.)
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