Fuji Electric FRENIC-AQUA series, User Manual

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2.8 Precautions for Using Inverters
2-43
Chap. 2
SP
ECIF
IC
A
T
IO
NS
Unusual
environments
Possible problems Sample measures Remarks
Fumigation for
export packaging Halogen compounds such
as methyl bromide used in
fumigation corrodes some
parts inside the inverter.
- When exporting an inverter built in a
panel or equipment, pack them in a
previously fumigated wooden crate.
- When packing an inverter alone for
export, use a laminated veneer lumber
(LVL).
Exporting.
„ 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 with a cable tie 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) Precautions for high frequency leakage currents
If the wiring distance between an inverter and a motor is long, high frequency currents flowing
through stray capacitance across wires of phases may cause an inverter overheat, overcurrent trip,
increase of leakage current, or it may not assure the accuracy in measuring leakage current.
Depending on the operating condition, an excessive leakage current may damage the inverter.
To avoid the above problems when directly connecting an inverter to a motor, keep the wiring
distance 50 m or less for inverters of 2.2 kW or below, and 100 m or less for inverters of a higher
capacity.
If the wiring distance longer than the specified above is required, lower the carrier frequency or
insert an output circuit filter (OFL-
††† - † A) as shown below.
When a single inverter drives two or more motors connected in parallel (group drive), in
particular, when using shielded wires, the stray capacitance to the earth is large, so lower the
carrier frequency or insert an output circuit filter (OFL-
††† - † A).
No output circuit filter installed Output circuit filter installed
Motor Inverter
Power
input
Max. 50 m
Max. 100 m
Inverter Motor
Max. 5 m
Max. 400 m
Output circuit filter
Power
input
For an inverter with an output circuit filter installed, the total secondary wiring length should be
400 m or less.
If further longer secondary wiring is required, consult your Fuji Electric representative.
(5) Precautions for surge voltage in driving a motor by an inverter
If the motor is driven by a PWM-type inverter, surge voltage generated by switching the inverter
component may be superimposed on the output voltage and may be applied to the motor
terminals. Particularly if the wiring length is long, the surge voltage may deteriorate the
insulation resistance of the motor. Implement any of the following measures.
- Use a motor with insulation that withstands the surge voltage. (All Fuji standard motors
feature reinforced insulation.)
- Connect a surge suppressor unit (SSU50/100TA-NS) at the motor terminal.
- Connect an output circuit filter (OFL-
††† - † A) to the output terminals (secondary circuits)
of the inverter.
- Minimize the wiring length between the inverter and motor (10 to 20 m or less).