From the above ladder logic program please answer the follow

From the above ladder logic program, please answer the following

What is the purpose of interconnecting the two timers?

How much time must elapse before output PL is energized

What two conditions must be satisfied for timer T4:2 to start timing?

Assume that output PL is on and power to the system is lost. When power is restored, what will the status of this output be?

When input PB2 is on, what will happen?

When input PB1 is on, how much accumulated time must elapse before rung 3 will be true?

Output Ladder logic program L2 T41 RES P82 L1 Inputs T4:2 0O-P81 RES )PL o--PB2 -RTO P81 RETENTIVE TIMER ON Timer Time base Preset Accumulated 4:1EN 2 HE Ties b 2900 1.0 DN PB1T4:1ETE RETENTIVE TIMER ON Timer Time base Preset Accumulated T42EN 3 1.0 DN 1780 (on) DN T42 HE DN

Solution

Timers used are RTO - retentive timer which need to two inputs to start timing and to reset. The timer will retains timing value until reset input is on. This timer thus if power is lost suddenly, it will start timing from where it left not from 0.

a) The purpose of inter connecting two timer is to increase on delay time of output PL .

b) Time must elapse before output PL is energized is sum of preset values of both timers

2900 + 1780 = 4680 s

c) To start timer T4:2 we need to turn on PB1 and T4:1 should reach preset value of 2900 sec.

d) Given PL is on and power is lost, when power restores PL will be in on state because timer used will not reset if power to it lost until it was reset using reset switch.

e) PB2 if on then the timer will reset to 0.

f) PB1 is on then time must be elapse before rung 3 will be true is 2900 sec.