Each RegFGC3 card can act on the protection chain of the converter. The protection chain acts on SKMCB pins 10,11 which controls the undervoltage coil of the MCB and interrupts the circuit immediately.

The state machine for example has several inputs that act on this chain;

• SK MCB (pin15) is connected to the MCB trip indication (SD Contact, page 47 NSX manual)
• SKPRECH (pin 7) is connected to the precharge circuit breaker auxiliary contact.
• SK_24V? is connected to the power module to indicate a fault
• SKEXTINTL is connected to:
  • pins 1,2 (External interlock 1-1) typically used in case of EIS for veto ch A
  • pins 3,4 (External interlock 1-2) typically used in case of EIS for verto ch B
  • pins 6-7 (external interlock 2-1 typically used for other uses described in EDMS2573244
• Other RegFGC3 cards (vs regulation, analog interlock etc.)