T1/DN Ensures That Door Is Closed for 3 Secs

Rung 0

We see that IP0, IP3 and OP3 are connected in parallel. OP3 (NO) is sealing contact. Hence, it will close only when OP3 (door close motor) operates. IP3 is internal call contact and IP0 is external call contact. Pressing of either of these contacts will give signal to operate door closing motor if door is not stuck up(IP4), elevator going up motor (OP0) has not operated and T4 has also not started counting down(T4/DN).

Rung 1

Operation of door closing motor (OP3) activates timer T1. It will count up to 3secs and then will start counting down (T1/DN).

Rung 2

T1/DN ensures that door is closed for 3 secs.

OP3 also ensures that door is closed. Both these contacts ensure that elevator will start going up 3 secs after the door is closed.

IP2 ensures that elevator is at level 1. It becomes NC when elevator is at level 1.

OP0 is sealing contact and closes after OP0 has operated.

T4/DN NC contact ensures that it has not started counting down.

Rung 3

Timer T3 starts operating elevator starts moving up. It is set at 3 secs and will pick up this time.

Rung 4

After elevator has reached at level2 and 3 secs have passed, door opening motor (OP2) will start opening. Operation of OP2 will OP6 will also activate OP2.

Rung 5

Operation of T2 will activate timer T3 which is preset at 3 secs. After 3 secs, T3 will start counting down.

Rung 6

Contact T3/DN activates resetting of T2 timer after 2 secs.

Rung 7

Timer T4 is activated if door is not stuck up (IP4), elevator is on level 2(IP1) and internal call button (IP3) or external call button (IP0) is activated.

Rung 8

OP1( elevator motor down) will be activated if IP2( elevator not on level 1) and T4/DN has become NO.

Rung 9

Closing of T4/DN contact activates timer T5.

Rung 10

Closing of T5/DN contact activates OP6.

Rung 11

Timer T6 will be activated by closing NO contact of OP6.

Rung 12

After 3 secs of becoming operative,, timer T6 will start counting down. Closing of T6/DN contact will reset timers T4,T5, T6 and T1 in 4,5,6 and 1 secs respectively.

Rung 13

Alarm OP4 will be activated if lift/door is stuck up after IP6 contact closes.