Specifications

33
Noise Countermeasures
The low-noise type uses high-carrier frequency PWM control, and compared to the low-carrier type tends to suffer from increased
electromagnetic interference (EMI). Following are suggestions that may be effective in reducing EMI effects in your installation:
• Lower the carrier frequency (constant n46) and the interference will be reduced.
• A line noise filter is effective in eliminating sensor malfunction or AM radio static (see page 35).
• To eliminate inductive noise from the inverter power line, separate the signal lines [recommended 30cm (11.8in), minimum 10cm
(3.94in)] and use twisted-pair shielded cable.
Current Leakage Countermeasures
A floating capacitance exists between the inverter power line and other drive lines, and between ground (earth) and the motor. This may
carry high-frequency leakage current and affect other equipment. This phenomenon varies with the carrier frequency and the wiring
distance between inverter and motor. The following measures may help to minimize the effects.
Wiring distance between inverter and motor, and setting of carrier frequency
POWER
SUPPLY
INVERTER
M
SENSOR
+
–
SENSOR
POWER
SUPPLY
CONTROL
BOARD
Connect shielded cable to
0V line, not to the ground.
Separate the inverter
from power line and
signal line more than
30cm (11.8in).
Connect a noise filter.
VS mini J7
Connect a noise filter.
Connect with a capacitor (0.1µF)
Use twisted-pair shielded cable.
Do not ground direcitly to
VS mini J7
From the JEMA report
Phenomenon
Current Leakage to
Ground (earth)
Malfunction of ground fault interrupters and
leakage relays
• Lower the carrier frequency (constant n46)
• Use a ground fault interrupter resistant to high frequencies
(e. g. Mitsubishi Electric NV Series)
• Lower the carrier frequency (constant n46)
• Use an inverter with a built-in electronic thermal overload relay.
Malfunction of external thermal overload relays
due to high-frequency component of leakage
current
Inter-line Leakage
Current
Countermeasures
Wiring Distance
Allowable carrier frequency
(Constant n46 set value)
10kHz or less
(1 to 4, 7, 8, 9)
5kHz or less
(1, 2, 7, 8, 9)
2.5kHz or less
(1, 7, 8, 9)
Up to 50m (164.0ft) Up to 100m (328.1ft)
More than 100m (328.1ft)