76 Rockwell Automation Publication 750-RM003A-EN-P - April 2018
Chapter 2 Bus Supply Hardware and Parameter Conversion
Figure 20 and Figure 21 show typical power and control power connections for 
a frame 8 PowerFlex 755TM bus supply with the optional control transformer 
(-C1 option code). The user-supplied 24V DC auxiliary control power is 
shown connected, but the bus supply functions without this power supply.
Table 38 - Operation Comparison
Operating Condition PowerFlex 700AFE Bus Supply, IP21 Rittal PowerFlex 700AFE Bus Supply, IP20 2500 
MCC
PowerFlex 755TM Bus Supply
3 PH, AC power 
application
• Manually energize the main incoming 
disconnect circuit breaker (Q0).
• Manually energize the main incoming 
disconnect circuit breaker (Q0).
• Manually energize the input disconnect 
switch (FD1).
• Initiation of precharge sequence depends on 
input from door operator or remote devices 
are switched to on/start.
• Precharge contactor (K6) is energized to 
supply a separate reduced DC power source to 
charge the DC bus.
• Initiation of the precharge sequence depends 
on input from door operator or that the 
remote devices are switched to on/start.
• Precharge contactor (K6) is energized to 
supply a separate reduced DC power source to 
charge the DC bus.
• Precharge is initiated immediately.
• Precharge contactor (M1) is energized to 
supply reduced AC to LCL filter and 
converter. Diodes within the IGBT devices 
are used to charge the DC bus.
• When precharge is completed, the MCCB (Q1) 
is energized supplying full 3 PH, AC power to 
the converter.
• When precharge is completed, the AC 
contactor (K1) is energized supplying full 
3 PH, AC power to the converter.
• When precharge is completed, the motor-
operated MCB circuit breaker (CB1) is 
automatically energized supplying full 
3 PH, AC power to the converter.
• When MCCB (Q1) closes and provided there 
are no start inhibits, the relay logic 
automatically energizes a Digital input 
configured to start IGBT modulation.
• When the AC contactor (K1) is energized and 
there are no start inhibits, the relay logic 
automatically energizes a Digital input that is 
configured to start IGBT modulation.
• When the MCB (CB1) is energized and 
there are no start inhibits, the user-
configured IGBT modulation stop/start/
run control starts IGBT modulation.
AFE is switched off/
stopped
• The door operator or remote devices are 
switched to off.
• The door operator or remote devices are 
switched to off.
• User-configured IGBT modulation stop/
start/run control requests stop IGBT 
modulation.
• IGBT modulation stops immediately.
• The MCCB (Q1) is de-energized.
• DC bus output voltage decays toward zero.
• Initiation of precharge sequence and restart 
of IGBT modulation requires input from the 
door operator or remote devices.
• IGBT modulation stops immediately.
• The AC contactor (K1) is de-energized.
• DC bus output voltage decays toward zero.
• Initiation of precharge sequence and restart 
of IGBT modulation requires input from the 
door operator or remote devices.
• IGBT modulation stops immediately.
• The MCB (CB1) stays energized.
• DC bus output drops to rectification 
voltage provided by the IGBT device 
diodes.
• Provided there are no start inhibits, IGBT 
modulation is restarted by the user-
configured stop/start/run control.
• If the  button on the HIM is pressed, 
IGBT modulation is stopped, but the MCCB 
(Q1) stays energized.
• DC bus output drops to rectification voltage 
provided by the IGBT device diodes.
• If the  button on the HIM is pressed, 
IGBT modulation is stopped but the AC 
contactor (K1) stays energized.
• DC bus output will drop to rectification 
voltage provided by the IGBT device diodes.
•If Line Side stop
(1)
 is true, IGBT 
modulation is stopped but the AC circuit 
breaker MCB (CB1) stays energized.
• DC bus output drops to rectification 
voltage that is provided by the IGBT device 
diodes.
AFE is operating with 
IGBT modulation, 
followed by opening the 
input disconnect or loss of 
3 PH AC power
• Loss of AC power or manually de-energize the 
main incoming disconnect circuit breaker 
(Q0).
• Loss of AC power or manually de-energize the 
main incoming disconnect circuit breaker 
(Q0).
• Loss of AC power or manually de-energize 
the input disconnect switch (FD1).
• Loss of AC power and control power causes a 
fault and start/run inhibit. IGBT modulation l 
stops immediately.
• Loss of AC power and control power causes a 
fault and start/run inhibit. IGBT modulation 
stops immediately.
• Loss of AC power and control power 
causes a fault and start/run inhibit. IGBT 
modulation stops immediately.
• The MCCB (Q1) de-energizes. • The AC contactor (K1) de-energizes. • The MCB (CB1) de-energizes.
(1) Line Side stop functionality can only be initiated by digital input 0:112 [DI L Stop] or by communication to Logix controller Add-On-Profile (AOP) Logic Command tags (Table 40). The HIM red button 
does not stop IGBT modulation.