Dear all,

I would like to ask a question regarding the behavior of a BLM when the 24 VDC supply is disconnected from the EP terminal. According to Function Diagram 8732, transitioning from state S1 to S2 requires 24 VDC to be present at the EP terminal.

Once the system reaches state S3Operation, what happens if the 24 VDC is removed from the EP terminal? Does the BLM return to a safe condition (S1)? If so, how should the CU320 be configured so that, in an emergency situation where the 24 VDC is cut off, the BLM thyristors are reliably turned off?

Thank you all in advance.

JuanMa

Thank you very much for your response. We are working on emergency stops for a BLM/Drive system and were unsure how the BLM behaves when the 24 VDC supply is removed from the EP terminals. In the BLM state sequence, we observe that there are no transitions (from one state to another) that depend on the EP terminal status from S4 to S1 or S2. In an emergency situation, we do not find it useful to focus on the BLM’s EP; instead, we act on the Drive’s EP and on the switch that feeds (380 Vca) the BLM.
 

Kind regards

JuanMa