VFD-B Series 
DELTA ELECTRONICS, INC. ALL RIGHTS RESERVED 
3-6
3.2 External Wiring 
Motor
Output AC 
Line Reactor
Power Supply
Magnetic
contactor
Input AC 
Line Reactor
EMI Filter
R/L1 S/L2
T/L3
U/T1 V/T2
W/T3
+2/B1
B2
Braking
Resistor
Zero-phase 
Reactor
DC
Choke
+1
Zero-phase 
Reactor
FUSE/NFB
 
Items Explanations 
Power 
supply 
Please follow the specific power 
supply requirement shown in 
APPENDIX-A. 
Fuse/NFB
(Optional)
There may be inrush current during 
power up. Please check the chart of 
APPENDIX B and select the correct 
fuse with rated current. NFB is 
optional. 
Magnetic 
contactor 
(Optional)
Please do not use a Magnetic 
contactor as the I/O switch of the AC 
drive, this will reduce the operating 
life cycle of the AC drive. 
Input AC 
Line 
Reactor 
(Optional)
In order to improve the input power 
factor, reduces harmonics and 
protection from AC line 
disturbances. (Surge, switching 
spike, power flick, etc.) AC line 
reactor should be installed when the 
power supply capacity is 500kVA or 
more and exceeds 6 times of the 
inverter capacity, or the wiring 
distance within 10m. 
Zero-phase 
Reactor 
(Ferrite 
Core 
Common 
Choke) 
(Optional)
Zero phase reactors are used to 
reduce radio noise specify when the 
audio equipments installed near the 
inverter. Good effective for noise 
reduction on both the input and 
output sides. Attenuation quality is 
good in a wide range from AM band 
to 10Mhz. Appendix B for specifies 
zero phase reactors. (RF220X00A) 
EMI filter 
(Optional)
To reduce the electromagnetic 
interference. Please refer to 
Appendix B for detail. 
Braking 
Resistor 
(Optional)
Used to reduce stopping time of the 
motor. Please refer to the chart on 
Appendix B for specific Braking 
Resistors. 
Output AC 
Line 
Reactor 
(Optional) 
 
Motor surge voltage amplitudes 
depending on the motor cable 
length. For long motor cable 
application, it is necessary installed 
on the inverter output side.