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E6580757
A-14
1
Power
supply
Leak current path across ground
ELCB
M
M
ELCB
Inverter
Inverter
Remedies:
1.Reduce PWM carrier frequency.
The setting of PWM carrier frequency is done with the parameter .
2.Use high frequency remedial products (Schneider Toshiba electric corporation: Esper Mighty
Series) for earth leakage breakers. If you use equipment like this, there is no need to reduce
the PWM carrier frequency.
3.If the sensors and CRT are affected, it can be remedied using the reduction of PWM carrier
frequency described in 1 above, but if this cannot be remedied since there is an increase in the
motor's magnetic noise, please consult with Toshiba.
(2)E ffects of leak current across lines
Power
supply
Thermal relay
Leak current path across wires
CT
A
M
Inverter
(1) Thermal relays
The high frequency component of current leaking into electrostatic capacity between inverter out-
put wires will increase the effective current values and make externally connected thermal relays
operate improperly. If the wires are more than 50 meters long, it will be easy for the external ther-
mal relay to operate improperly with models having motors of low rated current (several
A(ampere) or less), especially the 400V class low capacity (3.7kW) models, because the leak cur-
rent will increase in proportion to the motor rating.