Mitsubishi Electric F700 Instruction Manual page 23

Wiring
(2) Notes on earthing (grounding)
• Leakage currents flow in the inverter. To prevent an electric shock, the inverter and motor must be earthed (grounded). This
inverter must be earthed (grounded). Earthing (Grounding) must conform to the requirements of national and local safety
regulations and electrical codes. (NEC section 250, IEC 536 class 1 and other applicable standards)
A neutral-point earthed (grounded) power supply for 400V class inverter in compliance with EN standard must be used.
• Use the dedicated earth (ground) terminal to earth (ground) the inverter.
(Do not use the screw in the casing, chassis, etc.)
• Use the thickest possible earth (ground) cable. Use the cable whose size is equal to or greater than that indicated in page
14, 15 and minimize the cable length. The earthing (grounding) point should be as near as possible to the inverter.
To be compliant with the EU Directive (Low Voltage Directive), earth (ground) the inverter according to
the instructions on page 155.
(3) Total wiring length
The overall wiring length for connection of a single motor or multiple motors should be within the value in the table below.
Pr. 72 PWM frequency selection Setting
(carrier frequency)
2 (2kHz) or less
3 to 15 (3kHz to 14.5kHz) *
* For the 75K or more, the setting range of Pr. 72 PWM frequency selection is "0 to 6".
When driving a 400V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the
motor terminals, deteriorating the insulation of the motor.
Take the following measures 1) or 2) in this case.
1) Use a "400V class inverter-driven insulation-enhanced motor" and set frequency in Pr. 72 PWM frequency selection
according to wiring length
Pr. 72 PWM frequency selection Setting
(carrier frequency)
2) Connect the surge voltage suppression filter (FR-ASF-H) to the 55K or less and the sine wave filter (MT-BSL/BSC)
to the 75K or more on the inverter output side.
CAUTION
· Especially for long-distance wiring, 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 a malfunction or fault
of the equipment connected on the inverter output side. If fast-response current limit function malfunctions, disable this function.
(For Pr.156 Stall prevention operation selection, refer to the chapter 4 of the Instruction Manual (applied).)
· For details of Pr. 72 PWM frequency selection , refer to the chapter 4 of the Instruction Manual (applied). (When using an optional sine
wave filter (MT-BSL/BSC) for the 75K or more, set "25" in Pr.72 (2.5kHz)).
· For explanation of surge voltage suppression filter (FR-ASF-H) and sine wave filter (MT-BSL/BSC), refer to the manual of each
option.
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Total wiring length (1.5K or more)
300m + 300m = 600m
50m or less
14.5kHz or less
0.75K 1.5K
300m 500m
200m 300m
500m or less
300m
300m
Wiring Length
50m to 100m
9kHz or less
2.2K or More
500m
500m
exceeding 100m
4kHz or less