How Electrical Timers Work
This article is about the Timers, Types of the Timers, How Electrical Timers work.
Timers mostly used in the industries for making the control logics for the process control and various controlling purpose which needs a time gap. It also play an important role in the saving of the energy. Timers also used in the household appliances like Air-conditioner or washing machines and microwave ovens etc. timers are used to give delay from milli-seconds to the seconds, minutes, hours or few days also.
When we give the supply to the coil of the timers it energizes the coil. The timers have three basic contacts that is- NO ( normally open ), NC ( normally closed ) and COMMON.
The coil voltage given on the two terminal of the timer are A1 and A2. These contacts have changed their states after the time has reached to their preset time. Once the timer coil energizes it starts counting time from 0 to the preset time or preset time to 0 according to the on delay timer and off delay timer. When accumulated time and the preset time are equal timer interchange their contacts. The contacts like NC which closed the circuit in the starting and no which break the circuit in the starting when time of the timer has completed they change their status from NC to NO and NO changes to the NC.
Types of the timers
There are two types of the timers are available :-
- ON Delay Timer
- OFF Delay Timer
ON Delay Timers
ON-Delay Timers are used to switch ON the appliances or equipments after certain delay of the time. When the coil of the timer energizes the timer starts counting from 0 to the preset time.
When timer gets ON and starts counting from to the preset time this time is called accumulated time.
The time which is set in the time for the delay to start the appliances is known as the preset time.
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When accumulated time and the preset time are equal then the timer changes their contacts status the contacts which are NO in the timer when coil not energized changed their status to the NC and similar t the NC contacts.
On Delay Timing Graph
ON delay timers are used in the star delta starter
OFF Delay Timers
OFF Delay Timers are used to switch off the appliances or devices after the certain interval of the time. When coil of the timer energizes it start counting the time from preset to 0.
When the preset time and accumulated time is equal. The contacts of the timer has change their status .
Off Delay Timing Graph