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Chapter 1 electro mecha device part 3
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- 1.
- 2. Off Delay (delay on release) timer
- -is a device which does not start its timing
- function until the power is remove from the
- -when control switch is close, the timer
- contact change immediately and provide
- -Time period start counting when the power
- is removed from the timer.
- -timer return to its normal position (switch
- open) whenever time period,T is achieved
- and the load de-energized.
- 3. Off Delay
- -maybe used to provide cooling in a
- projector once the bulb has been turn off
- but has no time to cool down.
- -closing switch S1 will turn ON the
- projector bulb and activate timer coil
- -Normally open contact TR1 will
- immediately close energize fan motor
- which control the cooling of the
- -When S1 open, will turn off the projector lamp &
- power is removed from the timer.
- -Contact TR1 is remain closed for a period time, T
- and open after the predetermined period is
- passed .Cooling fan motor turn off.
- 4. One shot(interval) timer
- -is a timer where contact change position
- and remain change for the set period of
- time after timer received power.
- -is used which load is ON for period set
- 5. Application of one shot timer.
- -use in application which require ON and
- -in this case, it use for control the amount
- of time the plastic wrap is wound around
- -photoelectric switch detect pallet enter
- -Once detected, one shot timer will
- activated, contact close start wrapping
- -Wrapping process continues for the