Mitsubishi Electric fr-e700 series, Instruction Manual

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Wiring Electromagnetic compatibility (EMC)
FR-E700 SC EC/ENE 3 - 49
쑶
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Countermeasures
– Use Pr. 9 "Electronic thermal O/L relay".
– If the carrier frequency setting is high, decrease the Pr. 72 "PWM frequency selection" setting.
Note that motor noise increases. Selecting Pr. 240 "Soft-PWM operation selection" makes the
sound inoffensive. To ensure that the motor is protected against line-to-line leakage currents,
it is recommended to use a temperature sensor (e.g. PTC element) to directly detect motor
temperature.
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Selecting a power supply circuit breaker:
You can also use a circuit breaker (MCCB) to protect the power supply lines against short circuits
and overloads. However, note that this does not protect the inverter (rectifiers, IGBT). Select the
capacity of the circuit breaker on the basis of the cross-sectional area of the power supply lines.
To calculate the required mains current trip point you need to know the power required by the
inverter (Refer to rated input capacity in Appendix A.1, Specifications) and the mains supply
voltage. Select a circuit breaker with a trip point that is slightly higher than calculated, particularly
in the case of breakers with electromagnetic tripping, since the trip characteristics are strongly
influenced by the harmonics in the power supply line.
Example
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Line-to-line leakage current data example
Dedicated motor: SF-JR 4P
Carrier frequency: 14.5 kHz
Used wire: 2 mm², 4 cores, cab tyre cable
Motor Capacity [kW] Rated Motor Current [A]
Leakage Currents [mA]
Wiring Length 50 m Wiring Length 100 m
0.4 1.1 620 1000
0.75 1.9 680 1060
1.5 3.5 740 1120
2.2 4.1 800 1180
3.7 6.4 880 1260
5.5 9.7 980 1360
7.5 12.8 1070 1450
Tab. 3-23: Line-to-line leakage current data example
I001043E
Fig. 3-43: Line-to-line leakage currents
NOTE The earth leakage breaker must be either a Mitsubishi earth leakage breaker (ELB, for harmonics
and surges) or an ELB with breaker designed for harmonic and surge suppression that is approved
for use with frequency inverters.
Power
supply
Inverter
Line-to-line
leakage currents
path
Line-to-line static
capacitances
M
3~
Thermal
relay
Motor