Toshiba TOSVERT VF-AS3, Instruction Manual

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E6582062 
2. Installation and wiring
2-68
2
9
2. 4. 3 What to do about leakage current
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 circuit 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.
Here are some examples of measures against leakage current across ground.
• When there is no radio-noise interference or similar problem, switch the grounding capacitor of the
EMC noise filter to "disconnected" (size A1 to A5) or "small capacitance" (size A6 to A8).
For how to switch the grounding capacitor, refer to [2. 3. 4].
• Decrease <F300: Carrier frequency>.
When there is no concern against the magnetic noise from the motor, carrier frequency reduction
is effective measure. For details, refer to [6. 14].
• Use high frequency remedial products for ELCBs.
• Zero-phase reactor
It may be effective over the motor cable.
Built-in noise filter
The 480 V models of this inverter has a built-in EMC noise filter, so the leakage current value in the
delta connection (single-phase grounding) power supply may become greater. For detail, refer to
application manual "leakage current" (E6581181).
CAUTION
Mandatory
action
• 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.
M
Inverter
ELCB
M
Inverter
ELCB
Power
supply
Leakage current path across ground