Precautions For Using Inverters - Fuji Electric FRENIC-HVAC Manual

1.2 Precautions for Using Inverters

When handling inverters, be sure to observe the wiring precautions given below.
(1) 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.
(2) 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
(164 ft) or less for inverters of 2.2 kW (3HP) or below, and 100 m (328 ft) or less for inverters with 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-
When the inverter drives two or more motors connected in parallel (group drive), in particular, using
shielded wires, the stray capacitance to the earth is large, so lower the carrier frequency or insert an output
circuit filter (OFL-
No output circuit filter installed
Power
input
Inverter
Max. 50 m (164 ft)
Max. 100 m (328 ft)
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.
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- A) as shown below.
- A).
Motor
Output circuit filter installed
Power Max. 5 m (16 ft)
input
Inverter
1-2
Output circuit filter
Motor
Max. 400 m (1312 ft)