INDUSTRIAL AUTOMATION | Explain the following with diagram: i) Temperature Switch ii) Pressure Switch

Temperature Switch: 

A temperature switch is one detecting the temperature of an object. Temperature switches often use bimetallic strips as the temperature-sensing element, the motion of which actuates one or more switch contacts. An alternative design uses a metal bulb filled with a fluid that expands with temperature, causing the switch mechanism to actuate based on the pressure this fluid exerts against a diaphragm or bellows.

          Bimetallic strips are used as thermal switch in controlling the temperature or heat in a manufacturing process or system. It contains two different metal strips bonded together. The metals have different coefficients of expansion. On heating the strips bend into curved strips with the metal with higher coefficient of expansion on the outside of the curve. Figure 2.5.1 shows a typical arrangement of a bimetallic strip used with a setting-up magnet. As the strips bend, the soft iron comes in closer proximity of the small magnet and further touches. Then the electric circuit completes and generates an alarm.

Pressure Switch:

A pressure actuated switch is a device designed to monitor a process pressure and provide an output when a set pressure (setpoint) is reached. A pressure actuated switch does this by applying the process pressure to a diaphragm or piston to generate a force which is compared to that of a pre-compressed range spring. 

A pressure actuated switch is used to detect the presence of fluid pressure. Most pressure switches se diaphragm or below as the sensing element. The movement of this sensing element is used to actuate one or more switch contacts to indicate as alarm or initiate a control action.