Mitsubishi Electric FR-A700 Instruction Manual page 96

Electromagnetic compatibility (EMC)
Note on selecting a suitable power supply ELCB
If you install a Mitsubishi frequency inverter with a 3-phase power supply in locations where an
earth leakage contact breaker is required by the VDE you must install a universal-current sen-
sitive ELCB conforming to the specifications laid down in VDE 0160 / EN 50178 (ELCB Type B).
This is necessary because pulse-current sensitive ELCBs (Type A) do not pro-vide reliable trip-
ping performance for the frequency inverter in response to DC leakage current.
When selecting a suitable universal-current sensitive ELCB you must also take into account the
influence of the mains filter, the length of the shielded motor power cables and the frequency on
the leakage currents.
Also note that when the mains power is switched on with switches without a snap-action function
the resulting brief asymmetrical load can cause unwanted triggering of the ELCB.
This problem can be avoided by using a Type B ELCB with a delayed response function, or by
using a contac-tor relay to switch all three phases simultaneously.
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:Leakage current of inverter input side noise filter
Igm:Leakage current of motor during commercial power supply operation
Igi:Leakage current of inverter unit
Fig. 3-46: Leakage currents
NOTE For star connection, the amount of leakage current is 1/3.
3 - 58
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]
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]
Wiring
I001044E