Introduction to Industrial Automation

Figure 3.23  (a) Automation circuit for pump operation with cancellation possibility and time 

graphs of basic components, without flow (b), and with flow (c).

N

C

50 Hz 230 V

R

Stop

Start

e

C

T

C

Flow switch 

NC contact

T

d

T

e

Overload

fault

indicator

Machine

operation

indicator

Reset

d

Cancellation

indicator 

Figure 3.24  Automation circuit for pump operation with cancellation possibility and complete 

signaling.

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  Introduction to Industrial Automation

canceling of operation) for a proper operation of the discussed application. In the case of cancella-

tion, the automation circuit will lock, while not allowing further operation of the pump. In order 

to allow the further pump operation, the operator should have to press the “Reset” button, which 

forces a notification of the reason that caused the cancellation of the operation.