Q. In a hundred-line exchange 24 two-motion selectors are used. Draw schematic you suggest for this exchange and illustrate its working. How many simultaneous calls can be made during peak hour in this exchange?

Ans:

Desired schematic for 100 lines exchange with 24 two motion selectors is displayed in Figure.

In the case, 24 simultaneous calls can be put through the switch .Characteristically a 24-outlet Uni-selector is used as a selector hunter. Each of 24 outlets is connected to one two-motion selector. Hence a subscriber has access to all 24 two-motion selectors in the system. Corresponding outlets of all the selector hunters are commoned and So all subscribers have access to all two-motion selectors. This scheme is displayed in Figure. Call establishment in this scheme occurs in two steps. Firstly, when subscriber lifts his receiver handset, his Uni-selector hunts through contact positions and seizes a free two-motion selector. At thesubsequent step, two-motion selector responds to dial pulses for appropriate connection.