Introduction to Industrial Automation

Figure 3.13  Machine manipulation from multiple control panels (without operation signaling).

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  Introduction to Industrial Automation

N

C

1

50 Hz 230 V

R

Stop

Start

e

1

C

1

e

2

C

2

Stop

Start

C

2

C

1

C

2

Mechanical interlock symbol

Contact interlocking

C

2

 by C

1

Figure 3.15  Automation circuit with relays under electric and mechanic latching.

N

C

50 Hz 230 V

R

Stop

Start

e

C

(b)

N

C

50 Hz 230 V

R

Stop

Start

e

C

(a)

Stop

1

Stop1

Start

2

Start

2

1

2

3

4

5

6

Stop1

Start

2

3n-2

3n-1

3n

Console

3n wires

(d)

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C

1

50 Hz 230 V

R

e

1

1

2

3

C

1

C

2

e

2

4

5

6

C

2

C

n

e

n

3n-2

3n-1

3n

C

n

(c)

Figure 3.14  Control panel for n machines. (a) Centralized control panel for 1 machine, 

(b) decentralized control panel for 1 machine, (c) decentralized automation for n-machines, and 

(d) console for the decentralized automation of n-machines.

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Industrial Automation Synthesis 

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In cases of expensive and large motors with inversion, as presented in Section 3.4.1, the power 

circuit contains two relays for the change of phases (change of rotation), the electrical latch is not 

sufficient. Due to the catastrophic results that would result from an unwanted potential mechani-

cal energizing of those two relays, a “mechanical latch” is added in the automation. The mechani-

cal latch is a mechanism adapted on two relays and the activation of one relay is not allowed in any 

way when the other relay has been energized. The operation is called mutual exclusion.

A different kind of latch could happen when energizing a relay before another one which should 

have already been energized. It is straightforward that this latching is achieved through the utiliza-

tion of an NO contact of one relay in the activation branch of the other relay. The combined opera-

tion of this form, for two or more machines, is generated from the way that the physical process is 

being carried through the utilized machines. Such an application will be examined subsequently.