Advantech ADAM-6050 18-Channel Isolated Digital I/O Modbus TCP Module ADAM-6050-BE Data Sheet

Product codes
ADAM-6050-BE
Page of 272
253
Appendix C  
C.2.3 Normal Mode and Common Mode
Have you ever tried to measure the voltage between a live circuit and a 
concrete floor? How about the voltage between neutral and a concrete 
floor? You will get nonsense values. ‘Hot’ and ‘Neutral’ are just rela-
tional signals: you will get 110VAC or 220VAC by measuring these sig-
nals. Normal mode and common mode just show you that the Frame 
Ground is the most important reference signal for all the systems and 
equipments.
Figure C.4: Normal  and Common Mode.
•  Ground-pin is longer than others, for first contact to power system and 
noise bypass.
•  Neutral-pin is broader than Live-pin, for reducing contact impedance.