Question

3) LIST 4 MODES of timing relays 4L NO "A Explain what happens when Push "A you Explain what happens when you push "B"

Answer 1

Answer 3)

The four modes of Timing Relays are

1. On-delay mode: In this mode the timer turns on the output signal after a preset delay after receiving the input signal.

2. Off-delay mode: In this mode the timer turns off the output signal after a preset delay after receiving the input signal.

3. Interval mode: Here the timer turns on as soon as an input signal is received and remains on for a preset time interval.

4. Flicker mode: In this case the timer goes through several on-off cycles after an input signal is received.

Answer 4)

Sequence of events when pushbutton A is pressed

1. When pushbutton A is pressed then circuit to coil C is completed as N/C contact of pushbutton B is already closed.

2. This energizes the coil C.

3. Therefore N/O contact of coil C is also closed. As this N/O contact is in parallel with push-button A, therefore an alternate electrical path to coil C is setup.

4. Hence C remains on even if pushbutton A is released.

Next, sequence of events when 'B' is pushed:

1. When B is pushed then its NC contact, which is series with coil C, is opened.

2. This turns coil C off.

3. No C can be turned on only by pushing 'A'

Hope this helps.