TonsdonSwitch
- Aug 10, 2016
- 3
- Joined
- Aug 10, 2016
- Messages
- 3
Hello all, first post here and new electronics student. I have an assignment that is asking what are the least amount of steps to sound the alarm horn on rail 105 in the attached ladder diagram. I have come up with the below:
1) Selector switch SS101 to P2 (rail 101)
2) Momentary Button PB102 (rail 102) pushed and held for 10 seconds to activate on delay relay TD106 (rail 106)
CR 103 is normally closed so I want to keep it in shelf state and current should flow to AH105, sounding the alarm horn.
However, I received a hint that 4 steps are required and I will need to switch the selector switch to P3 after activating the on delay relay TD106. I cannot see a reason why this is necessary as CR103 (rail 105) is normally closed and energizing will open the relay, stopping the current from flowing to the horn.
This is driving me crazy, I've scoured online resources and have been unable to find why energizing CR103 is necessary.
Another question I have, is once TD 106 On Delay Relay is energized, and MomentaryPush Button PB102 is lifted, will TD106 stay closed? I'm leaning towards TD106 reverting back to open state once no longer energized and current no longer flowing through rail 105.
The assignment also asks for the steps in shutting the alarm horn off, but I'm hoping I can figure that out once I can figure out turning it on.
Thank you for any help!
[2016-12-04, Harald Kapp: attachment deleted upon sensible request by the op]
1) Selector switch SS101 to P2 (rail 101)
2) Momentary Button PB102 (rail 102) pushed and held for 10 seconds to activate on delay relay TD106 (rail 106)
CR 103 is normally closed so I want to keep it in shelf state and current should flow to AH105, sounding the alarm horn.
However, I received a hint that 4 steps are required and I will need to switch the selector switch to P3 after activating the on delay relay TD106. I cannot see a reason why this is necessary as CR103 (rail 105) is normally closed and energizing will open the relay, stopping the current from flowing to the horn.
This is driving me crazy, I've scoured online resources and have been unable to find why energizing CR103 is necessary.
Another question I have, is once TD 106 On Delay Relay is energized, and MomentaryPush Button PB102 is lifted, will TD106 stay closed? I'm leaning towards TD106 reverting back to open state once no longer energized and current no longer flowing through rail 105.
The assignment also asks for the steps in shutting the alarm horn off, but I'm hoping I can figure that out once I can figure out turning it on.
Thank you for any help!
[2016-12-04, Harald Kapp: attachment deleted upon sensible request by the op]
Last edited by a moderator: