Mitsubishi Electric FR-D720S SC EC Instruction Manual page 82

Electromagnetic compatibility (EMC)
Note on selecting a suitable power supply ELCB
If your application requires by installation standards an RCD (residual current device) as up
stream protection please select according to DIN VDE 0100-530 as following:
Single phase inverter type A or B
Three phase inverter only type B
Additionally, when selecting a residual current device (RCD), leakage current caused by the
mains filter, the length of the shielded motor cable and the carrier frequency must be taken into
consideration.
When connecting AC current using switches without a step function, brief asymmetrical loads
may result in unwanted triggering of the residual current device (RCD). It is recommendable
here to use a Type B residual current device (RCD) with delayed actuation or to switch on all
three phases simultaneously using a main contactor.
Calculate the trip current sensitivity of the ELB as follows:
● Breaker designed for harmonic and surge suppression:
IΔn ≥ 10 × (Ig1 + Ign + Igi + lg2 + lgm)
● Standard breaker:
IΔn ≥ 10 × [Ig1 + Ign + Igi + 3 × (Ig2 + lgm)]
Ig1, Ig2: Leakage currents in wire path during commercial power supply operation
Ign:
Igm:
Igi:
Example of leakage current per 1km
during the commercial power supply
operation when the CV cable is
routed in metal conduit
(200V/60Hz)
Power supply size [mm²]
Fig. 3-37: Leakage currents
NOTE For star connection, the amount of leakage current is 1/3.
3 - 46
Leakage current of inverter input side noise filter
Leakage current of motor during commercial power supply operation
Leakage current of inverter unit
Leakage current example of 3-phase
induction motor during the
commercial power supply operation
(200V/60Hz)
Motor capacity [kW]
Example of leakage current per 1km
during the commercial power supply
operation when the CV cable is
routed in metal conduit
(Three-phase three-wire delta
connection 400V/60Hz)
Power supply size [mm²]
Wiring
Leakage current example of 3-
phase induction motor during the
commercial power supply
operation
(Totally-enclosed fan-cooled type
motor 400V/60Hz)
Motor capacity [kW]
I001928E