Introduction to Industrial Automation

3.6   Automation Circuit Design Regulations

For the design of the automation circuits, multiple standards have been defined from national 

and international regulations, such as NEMA, DIN, BS, ANSI, IEC, etc. These standardization 

approaches from one point of view provide us with the freedom to select the best automation sym-

bols or design regulations, while on the other hand they can be considered problematic, in that 

since there is not a unified standardization approach that would enable the direct comprehension 

of various automated circuit designs.

Until now, there have been multiple automation symbols utilized progressively in the various 

presented applications. In Table 3.1, all the basic automation symbols that have been utilized are 

presented, while it should be noted that with this set of symbols, the majority of all of the indus-

trial automation could be designed. It is also obvious that these symbols are not the complete set 

of symbols that could be utilized in industrial automations and there are many more that could be 

referred to in the previously mentioned standardization automation manuals.

Except for the specific symbol that represents each device in an automation circuit, an Arabic 

letter is additionally utilized. The different devices and the corresponding letters are presented in 

N

C

1

50 Hz 230 V

R

e

C

1

C

2

C

2

C

1

C

2

TC

1

TC

2

b

1

b

2

Photocell

2 channel

transmitter

Receiver

Motion

to close

Motion

to open