Appendix B Accessories
 VFD-EL-W 
B-3 
 
Applications 
Connected in input circuit 
Application 1 
When more than one AC motor drives are connected to the same mains power and are running, and one of 
them is ON during operation. 
 
Issues:  When  applying  power  to  one  of  the  AC  motor  drives,  the  charge  current  of  the  capacitors  may 
cause voltage dip. The AC motor drive may be damaged when over-current occurs during operation. 
 
Correct wiring: 
M1
M2
Mn
AC motor drive
AC motor drive
AC motor drive
 
 
Application 2 
A silicon rectifier and AC motor drive are connected to the same power. 
 
Issues:  Switching  spikes  are  generated  when  the  silicon  rectifier  switches  ON/OFF.  These  spikes  may 
damage the mains circuit. 
 
Correct wiring: 
power
AC motor drive
Silicon Controlled Rectifier
 
 
Application 3 
The power supply capacity is 10 or above times the AC motor drive capacity. 
 
Issues: When the mains power capacity is too large, line impedance is small and the charge current is too 
high. This may damage the AC motor drive due to the higher rectifier temperature. 
 
Correct wiring: 
large-capacity
    power
reactor
AC motor drive