Fuji Electric FRENIC-HVAC User Manual page 80

Unusual
Possible problems
environments
Fumigation for Halogen compounds such
export packaging as methyl bromide used in
fumigation corrodes some
parts inside the inverter.
 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 (165 ft) or less for inverters of 3.7kW (5 HP) or below, and 100 m (328 ft) or less
for inverters of a higher capacity. Output circuit filters cannot be used with the three-phase 575V
class series.
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). Output circuit filters cannot
be used with the three-phase 575V class series.
No output circuit filter installed
Power
input
Inverter
Max. 50 m
Max. 100 m
For an inverter with an output circuit filter installed, the total secondary wiring length should be
400 m (1312 ft) 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 (33 to 66ft) or less).
Sample measures
- 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).
Output circuit filter installed
Power Max. 5 m
input
Motor
Inverter
2-47
2.8 Precautions for Using Inverters
Remarks
Exporting.
Output circuit filter
Motor
Max. 400 m