Introduction to Industrial Automation

Figure 3.10  Machine operation with: (a) a selectable auto-manual mode, and (b) with a time relay.

N

C

1

50 Hz 230 V

R

RS

1-2

Stop

Start

‘H’

‘A’

Command 1

1

2

(a)

Command 2 

e

1

C

1 or 2

C

2

e

2

1

2

(b)

N

C

1

50 Hz 230 V

R

RS

1-2

Stop

Start

‘H’

‘A’

Command 1 

1

2

Command 2 

e

1

C

1 or 2

C

2

e

2

d

d

 

 

Figure 3.11  Operation of two machines with selectable common manual commands or sepa-

rate automatic commands. (a) Automation based on additional contacts of a switch, (b) automa-

tion based on an auxiliary relay.

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90

 

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  Introduction to Industrial Automation

automation circuit is presented in two versions: with a double pole selective switch and with a 

single pole switch and an auxiliary relay.

3.2.8   Operation of Two Machines with a Common Automatic 

Command or Separate Manual Commands

For the proper understanding of this operation, we will refer to a non-industrial example. Let’s 

assume that we have the case of two farms equipped with one common watering pump station. 

For both of the farms, it is ideal to operate the common watering pumps on a daily (24 h) repeti-

tive schedule. At the same time, we would like to have the ability to operate the water pumps 

independently and exclusively for each farm with a corresponding charge, based on the individual 

consumption (or hours of operation). The required automation circuit for the operation of the 

watering pumps with a common automatic command or two separate manual commands is pre-

sented in Figure 3.12.