Mitsubishi Electric FR-D720S-008SC, Original Instruction

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8
WIRING
4.3.2 Maximum Permissible Motor Wiring Length
The maximum permissible length of the motor cables depends on the capacity of the inverter and the selected carrier frequency.
The lengths in the following table are for unshielded cables. When shielded cables are used divide the values listed in the table
by 2. Note that the values are for the total wiring length – if you connect more than one motor in parallel you must add the lengths
of the individual motor cables.
Single-phase 200 V class
Three-phase 400 V class
Note that the motor windings in three-phase AC motors are subject to far more stress when operated via frequency inverters than
with mains operation. The motor must have been approved by the manufacturer for operation on a frequency inverter.
In the PWM type inverter, a surge voltage attributable to wiring constants is generated at the motor terminals. Especially for a 400 V
class motor, the surge voltage may deteriorate the insulation. When the 400 V class motor is driven by the inverter, consider the
following measures:
앫
Use a "400 V class inverter-driven insulation-enhanced motor" and set frequency in Pr. 72 PWM frequency selection according to
wiring length.
앫
Limiting the voltage rise speed of the frequency inverter output voltage (dV/dT):
If the motor requires a rise speed of 500 V/μs or less you must install a filter in the output of the inverter. Please contact your
Mitsubishi Electric dealer for more details.
Setting of Pr. 72 PWM Frequency selection
(Carrier Frequency)
FR-D720S-
008SC 014SC 025SC 042SC 070SC
1 (1 kHz) or less 200 m 200 m 300 m 500 m 500 m
2 to 15 (2 kHz to 14.5 kHz) 30 m 100 m 200 m 300 m 500 m
Setting of Pr. 72 PWM Frequency selection
(Carrier Frequency)
FR-D740-
012SC 022SC 036SC 050SC 080SC
1 (1 kHz) or less 200 m 200 m 300 m 500 m 500 m
2 to 15 (2 kHz to 14.5 kHz) 30 m 100 m 200 m 300 m 500 m
Wiring Length
50 m 50 m–100 m 100 m
Carrier frequency 14.5 kHz 8 kHz 2 kHz
CAUTION
앫
Especially for long-distance wiring (particularly when employing shielded motor cables), the inverter may be affected by a charging
current caused by the stray capacitances of the wiring, leading to a malfunction of the overcurrent protective function or fast
response current limit function, or stall prevention function or a malfunction or fault of the equipment connected on the
inverter output side.
When the fast-response current limit function malfunctions, make the function invalid. When stall prevention function misoperates,
increase the stall level. (For Pr. 22
Stall prevention operation level and Pr. 156 Stall prevention operation selection , refer to the
Instruction Manual.)
앫
For details of Pr. 72 PWM frequency selection , refer to the Instruction Manual.
앫
When using the automatic restart after instantaneous power failure function with wiring length exceeding below, select
without frequency search (Pr. 162 = "1", "11"). (Refer to the instruction manual for further information to Pr. 162).
500 m or less
300 m
300 m
300 m + 300 m = 600 m
Motor capacity 0.1 K 0.2 K 0.4 K
Wiring length 20 m 50 m 100 m
Total wiring length (FR-D720S-070SC or more, FR-D740-080SC or more)