ABB AC 800M, Hardware And Operation

Page: 185 / 230

Appendix A Hardware Units Power Supply Units – Types SD821, SD822 and SD823
3BSE 027 941 R301 185
The output voltage of all three PSUs is a regulated, low noise, 24V DC. A green
LED on the PSU front panel indicates that the output circuit is providing the correct
output voltage level. The double connectors provided on the 24V DC output
terminals allow for connecting more than one piece of equipment.
A surge current limiter within the PSU circuit provides a soft-start feature.
Consequently the controlled power-on of a PSU will not trip fuses or ground-fault
circuit breakers. In addition, the normal disturbances that occur within an industrial
main network will not result in transient fault conditions or tripping.
This results in the surge current limiter effectively reducing the peak inrush current
caused by a power disruption, to a level the PSU can tolerate.
This soft-start, surge current limiter facility simplifies designing the system power
distribution circuits.
Figure 46. PSU’s SD821, 822 and 823 – Block Diagram
L
N
PE
L+
L+
L–
L–
Chopper
Fuse
X1 X2