Introduction to Industrial Automation

arate manual commands.

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Industrial Automation Synthesis 

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3.2.10   Control Panel for Operating n Machines

It is generally acceptable in the most ideal cases to have multiple independent machines controlled 

from the same control station or, as it is commonly stated, to have a common control panel. This 

control panel can be physically located on the complex machine, placed somewhere in the area of 

the machines, or even placed remotely in a special area for control and supervision. Figures 3.14a 

and 3.14b indicate the concept of having a decentralized installation of the control panel (control 

buttons and switches) far from the switchgear with power relays, thermal overload switches, etc. 

The desired automation circuit for the n machines is presented in Figure 3.14c, while in this circuit 

it is worth studying the number of the desired wires for completing the automation. It is straight-

forward for this implementation that three n wires are needed, as shown in Figure 3.14d. This 

number can be reduced to 2n+1 if the contacts of the thermal overload relays are placed between 

the relays C

i

 and Neutral. In both cases, the number of wires is increased by 1 if a visual indication 

is desired in the control panel, which is the common practice in most automation installations. 

This additional wire is needed for connecting the neutral phase, while the terminals 3, 6, 9, …, 

3n will supply the corresponding light indications.