英语翻译
Some contacts are normally open (Abbreviated "n.o." or "no") until closed by operation of the switch,while others are normally closed ("n.c.or "nc") and opened by the switch action,where the abbreviations given are commonly used on electronics diagrams for clarity of operation in assembly,analysis or troubleshooting.The serve to synchronize meaning with possible mistakes in wiring assembly,where wiring part of switch one way and part another (usually opposite) way will pretty much guarantee things won't work as designed.