Chapter 6, Problem 2P

Program Plan Intro

Break-make pushbutton switch:

• Break-before-make pushbutton is a switch whose top level section contacts are Normally Closed (NC) and bottom level section contacts are Normally Open (NO).
• The top level contacts will be opened before the bottom level contacts get closed when the pushbutton is pressed.
• An electrical symbol used to represent break-make pushbutton switch is given below.

Given:

The conventional hardwired relay circuit should perform the following circuit functions when two break-make pushbuttons are used.

• The light L1 must turn ON when pushbutton PB1 is pressed.
• The light L2 must turn ON when pushbutton PB2 is pressed.
• The pushbuttons must be interlocked electrically, such that L1 and L2 cannot be turned ON simultaneously.