
E6581090
Circuit interrupting when two or more inverters are used on the same power line.
| (circuit |
MCCB1 | MCCB2 interrupting fuse) |
| MCCB3 |
| MCCBn+1 |
INV1
INV2
INVn
1
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.
1.4.3What 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)
: About 1mA | ||
to 2007P | : About 6mA | |
to 1007P | : About 3mA | |
: About 11mA | ||
to 2022P | : About 3mA | |
: 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
ELCB
Inverter | M |
Inverter M
Leakage current path across ground