Leakage Current - Mitsubishi Electric FATEC FR-A800 Manual

7
REVIEW OF INSTALLATION ENVIRONMENT
7.2.4

Leakage current

The static capacitances exist between the inverter I/O cables and other cables or earth and in the
motor, through which a leakage current flows. Since its value depends on the static capacitances or
carrier frequency, the low acoustic noise operation at the increased carrier frequency of the inverter
will increase the leakage current. Therefore, take the following countermeasures. Select the earth
leakage circuit breaker according to its rated sensitivity current, independently of the carrier
frequency setting.
(1) To-earth (ground) leakage current
Type
Effect and counter-
measure
Undesirable current
path
7.2 Noise
112
Table 7.4 Effects and countermeasures of to-earth (ground) leakage current
• The leakage current may flow not only into the inverter's own line but also into the other
lines through the earthing (grounding) cable or the like. This leakage current may cause
an unnecessary operation of the earth leakage circuit breaker or earth leakage relay.
● Countermeasures
• If the carrier frequency setting is high, decrease E600 (Pr.72) PWM frequency selection
setting.
Note that the motor noise increases. Selecting E601 (Pr.240) Soft-PWM operation
selection makes the sound inoffensive.
• By using earth leakage circuit breakers that support harmonic and surge suppression in
the inverter's own line and other line, operation can be performed with a high carrier
frequency (with low noise).
Power
supply
Earth leakage
circuit breaker
Earth leakage circuit breaker
Effect and countermeasure
Inverter
NV1
NV2
Motor
C
C
Motor
C