What To Do About Leakage Current; Influence Of Leakage Current Across Ground - Toshiba TOSVERT VF-AS3 Instruction Manual

2. 4. 3
2
Mandatory
action
Measures should be taken for leakage current across ground and leakage current between wires
because they may cause a malfunction of peripheral device.

■ Influence of leakage current across ground

Leakage current may flow not just through the inverter system but also through grounding wires to
other systems. This leakage current will cause earth leakage breakers (ELCB), leakage current
relays, ground relays, fire alarms and sensors to operate improperly, and it will cause superimposed
noise on the TV screen or display of incorrect current detection with the CT.
Leakage current path across ground
9
Power
supply
Here are some examples of measures against leakage current across ground.
• When there is no radio-noise interference or similar problem, detach the grounding capacitor of
the EMC noise filter.
For how to switch the grounding capacitor, refer to [2. 3. 4]. In this case, be sure to set <F300: Car-
rier frequency> to 4 kHz or less for some capacity. If it is over 4kHz, the internal parts of the
inverter may be damaged.
• Decrease <F300: Carrier frequency>.
For details, refer to [6. 14].
However, when a low carrier frequency cannot be set because of increase in magnetic noise from
the motor, you can also adopt earth leakage breakers with enhanced measures for inverter.
Pleased contact your Toshiba distributor for details.
• Use high frequency remedial products for earth leakage breakers.
When further measures are required with long wire length, etc., decrease <F300: Carrier fre-
quency>.
2. Installation and wiring

What to do about leakage current

• Take countermeasures against leakage current.
The leakage current through the stray capacitance of the input/output power wires of inverter
and motor can affect peripheral devices. In that case, please take countermeasures such as
reducing the carrier frequency or shortening the length of input/output power wires. When the
total wire length (total length between an inverter and motors) is more than 100m, if the trip
occurs with the motor no-load current, make enough space between phase wires or insert the
filter (MSF: motor-end surge voltage suppression filter).
• Pay attention to the cable length
In case the total cable length (total of length between an inverter and motors) is 100 m or more,
a trip can occur even with no-load current. Make enough space among each phase cable or
install the filter (MSF) as countermeasure.
ELCB
ELCB
CAUTION
Inverter
Inverter
2-58
E6582062
M
M