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Chapter 1 electro mecha device part 3


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Chapter 1 electro mecha device part 3

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