Toshiba VF-nC1 - Manual (Page 20)

E6581090
A-11
1
Circuit interrupting when two or more inverters are used on the same power line.
MCCB1
MCCBn＋1
MCCB3
MCCB2
INV1
INV2
INVn
(circuit
interrupting fuse)
Breaking of selected inverter
There is no fuse in the inverter's main circuit. Thus, as the diagram above shows, when more than
one inverter is used on the same power line, you must select interupting characteristics so that
only the MCCB2 will trip and the MCCB1 will not trip when a short occurs in the inverter (INV1).
When you cannot select the proper characteristics install a circuit interrupting fuse between the
MCCB2 and the INV1.
■ Disposal
If an inverter is no longer usable, dispose of it as industrial waste.
1.4.3 What to do about leak current
Warning
Current may leak through the inverter's input/output wires because of insufficient electrostatic
capacity on the motor with bad effects on peripheral equipment. The leak current's value is
affected by the carrier frequency and the length of the input/output wires. Test and adopt the
following remedies against leak current.
(1) Leakage current from the inverter main unit
As compared with other types of inverters, a large amount of current leaks from your inverter
when it is used in delta connection (with one phase grounded). Take this into consideration when
selecting an earth leakage breaker.
<Leakage current in delta connection (one phase grounded)> (For reference only)
VFNC1-2001P to 2022P : About 1mA
VFNC1S-2002P to 2007P : About 6mA
VFNC1S-1001P to 1007P : About 3mA
VFNC1S-2002PL to 2007PL : About 11mA
VFNC1S-2015P to 2022P
: About 3mA
VFNC1S-2015PL to 2022PL : About 17mA
(2) Effects of leakage current across ground
Leakage current may flow not just through the inverter system but also through ground wires to
other systems. Leakage current will cause earth leakage breakers, leak current relays, ground
relays, fire alarms and sensors to operate improperly, and it will cause superimposed noise on the
CRT screen or display of incorrect current amounts during current detection with the CT.
Power
supply
ELCB
Inverter
Inverter
M
M
ELCB
Leakage current path across ground