3 SCRs are connected in series. The string efficiency is 91%. SCRs 1, 2 & 3 have leakage currents 4 mA, 8 mA & 12 mA. Which SCR will block more voltage?

The SCR that will block more voltage in a series connection is typically determined by the leakage current. The SCR with the highest leakage current (which will not contribute significantly to the blocking capability) will generally block the most voltage.

In this case:

– SCR 1: 4 mA

– SCR 2: 8 mA

– SCR 3: 12 mA

Since SCR 3 has the highest leakage current (12 mA), it will block the most voltage among the three SCRs.

Answer: SCR 3 will block more voltage.