Introduction to Industrial Automation

Figure 3.16  Sequential start-up of four machines with chain electric latching.

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  Introduction to Industrial Automation

3.3.2   Motor Operation with Power Supply from Two Different Networks

In large industrial units it is possible, for safety and cost reasons, to have the ability to select the supply 

from a different power network, instead of the one commonly provided. In this case, switching to a 

different power network is ideal. The automation circuit and power circuit needed for this application 

and the safe transition from one network to the other is presented in Figure 3.18. It should be high-

lighted that the utilization of the double latch is achieved through the contacts of the relays and from 

the utilization of the buttons. The utilized buttons have double contacts to allow initially one relay to 

be de-energized and subsequently the second relay to be energized during the change in the supply.

N

50 Hz 230 V

R

Stop

Start

d

1

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Figure 3.17  Sequential start-up of four machines with chain electric latching without reopera-