1-5
Chap. 1
BEFORE U
S
IN
G
THE IN
VE
R
T
ER
Storage environment
The storage environment in which the inverter is stored after purchase is different from the operation environment. For details,
refer to the FRENIC-MEGA User's Manual, Chapter 2.
Wiring precautions
(1) Route the wiring of the control circuit terminals as far from the wiring of the main circuit as possible. Otherwise electric noise
may cause malfunctions.
(2) Fix the control circuit wires inside the inverter to keep them away from the live parts of the main circuit (such as the terminal
block of the main circuit).
(3) If more than one motor is to be connected to a single inverter, the wiring length should be the sum of the length of the wires to
the motors.
(4) 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 inverter output.
3) If the cable from the inverter 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 inverter, an increase in leakage current, or a reduction in current
indication precision.
When a motor is driven by a PWM-type inverter, the motor terminals may be subject to surge voltage generated by inverter
element switching. If the motor cable (with 460 V series motors, in particular) is particularly long, surge voltage will
deteriorate motor insulation. To prevent this, use the following guidelines:
Inverter 7.5 HP and larger
Motor Insulation Level
1000 V
1300 V
1600 V
460 VAC Input Voltage
66 ft (20 m)
328 ft (100 m)
1312 ft (400 m)*
230 VAC Input Voltage
1312 ft (400 m)*
1312 ft (400 m)*
1312 ft (400 m)*
Inverter 5 HP and smaller
Motor Insulation Level
1000 V
1300 V
1600 V
460 VAC Input Voltage
66 ft (20 m)
165 ft (50 m)*
165 ft (50 m)*
230 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 inverter and the motor, the thermal O/L relay
may malfunction (particularly in the 460 V series), even when the cable length is 165 ft (50 m) or less. To correct,
insert a filter or reduce the carrier frequency. (Use function code F26 "Motor sound".)
• For the vector control mode, wiring length is 328 ft (100 m) or less.
(5) When an output circuit filter is inserted in the secondary circuit or the wiring between the inverter and the motor is long, a
voltage loss occurs due to reactance of the filter or wiring so that the insufficient voltage may cause output current oscillation
or a lack of motor output torque. To avoid it, select the constant torque load by setting the function code F37 (Load
Selection/Auto Torque Boost/Auto Energy Saving Operation 1) to "1" and keep the inverter output voltage at a higher level by
configuring H50/H52 (Non-linear V/f Pattern, Frequency) and H51/H53 (Non-linear V/f Pattern, Voltage).
Precautions for connection of peripheral equipment
(1) Phase-advancing capacitors for power factor correction
Do not mount a phase-advancing capacitor for power factor correction in the inverter's input (primary) or output (secondary)
circuit. Mounting it in the input (primary) circuit takes no effect. To correct the inverter power factor, use an optional DC
reactor (DCR). Mounting it in the output (secondary) circuit causes an overcurrent trip, disabling operation.
An overvoltage trip that occurs when the inverter is stopped or running with a light load is assumed to be due to surge current
generated by open/close of phase-advancing capacitors in the power system. An optional DC/AC reactor (DCR/ACR) is
recommended as a measure to be taken at the inverter side.
Input current to an inverter contains a harmonic component that may affect other motors and phase-advancing capacitors on
the same power supply line. If the harmonic component causes any problems, connect an optional DCR/ACR to the inverter.
In some cases, it is necessary to insert a reactor in series with the phase-advancing capacitors.
Summary of Contents for FRENIC-MEGA
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