Power Failure Detection And Bridging - Siemens SINUMERIK 840D sl Function Manual

R3: Extended stop and retract
6.2 Control-managed ESR
6.2.3

Power failure detection and bridging

DC link voltage limit values
The DC link is monitored against the limit values shown in the following diagram:
Figure 6-1
The drive and DC link pulses are cancelled at specific voltage levels, which means that the
drives coast-down. If this behavior is not desired, the excess energy can be discharged using
a resistor module. The operating range of the resistor module (shown highlighted in the
diagram) lies below the critical voltage level.
Note
The pulse power of the resistor module is greater than the infeed power.
Monitoring the intermediate circuit minimum voltage limit
The DC link voltage can be monitored against a limit value that can be parameterized in the
drive:
• p1248 (DC link voltage – lower voltage threshold)
When the limit value is fallen below, the following signal is set in the message word (MELDW)
of the PROFIdrive telegram:
• MELDW.Bit4 = 1 (VDC_min controller is active (Vdc link < p1248))
The signal can be used in the NC to initiate ESR responses.
Figure 6-2
366
DC link voltage limit values
Monitoring the DC link voltage
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
Special Functions