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Emc And Leakage Currents; Leakage Currents And Countermeasures; Installation Of Power Factor Improving Reactor - Mitsubishi Electric FR-F700PJ Instruction Manual

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EMC and leakage currents

3.1
EMC and leakage currents
3.1.1

Leakage currents and countermeasures

Capacitances exist between the inverter I/O cables, other cables and earth and in the motor, through which a leakage current
flows. Since its value depends on the static capacitances, carrier frequency, etc., low acoustic noise operation at the
increased carrier frequency of the inverter will increase the leakage current. Therefore, take the following measures. Select
the earth leakage current breaker according to its rated sensitivity current, independently of the carrier frequency setting.
(1)
To-earth (ground) leakage currents
Leakage currents may flow not only into the inverter's own line but also into the other lines through the earth (ground) cable,
etc. These leakage currents may operate earth (ground) leakage circuit breakers and earth leakage relays unnecessarily.
Suppression technique
 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.
 By using earth leakage circuit breakers designed for harmonic and surge suppression in the inverter's own line and other
line, operation can be performed with the carrier frequency kept high (with low noise).
REMARKS
When using Filterpack, the leakage current is about 4mA (8mA for the 400V class). (For one phase of the three-phase three wire
connection current)
In the operation with Filterpack, insulating the earthing (grounding) cable of the capacitive filter reduces leakage current. The
earthing (grounding) cable can be insulated by connecting it to the enclosed plastic spacer and securing it using the enclosed
plastic screw as a countermeasure against leakage current. However, the noise reduction effect of the capacitive filter will be lost.
(Pull out the earthing (grounding) cable for the capacitive filter a little to wire.)
Installation
NOTE
 When the earthing (grounding) cable for the capacitive filter of Filterpack is removed, the cable is charged while the
inverter power is ON and also shortly after the power OFF. Do not touch the earthing (grounding) cable as you may
get an electric shock.
42
Filterpack
Spacer
(plastic)
Earthing (grounding)
cable for capacitive filter
Screw for leakage current countermeasure (plastic)
(tightening torque: 0.35
0.05Nm)

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