GATE for Instrumentation

Sr. No Variable Sensor Remark 1 Temperature RTD(Resistance Temperature detector / Resistance Thermometer As temp. increase resistance increase. (mostly linear) Thermocouple (Two metals connected together) Active Transducer, generate voltage depends on temp. difference and material used. Thermistor NTC (Negative temperature coefficient), As temp. increase resistance decrease. Non linear Pyrometer Used for high temperature measurement LM 35 (Semiconductor IC) Most linear Temp. sensor Bimetallic Thermometer Two metal connected with different temperature coefficient 2 Flow Variable area flow meter ( rotameter )   Linear Scale, Float position change with flow, Q α h ...

   1. Passive Transducer:  No generation of voltage Eg. , Strain Gauge, RTD  (Resistance Temperature Detector),  Resistance Hygrometer, Thermistor,   Piezoelectric Transducer,  etc.  2. Active Transducer: Generation of voltage/current E.g.  Thermocouple, Piezoelectric Transducer, Photo-volatile Cell, Tachogenerator  3. Analog Transducer  E.g., Strain Gauge, LVDT, Thermocouple, Thermistor 4. Digital Transducer E.g.,  Tu rbine meter used in for flow measurement 5. Transducer (converts a non-electrical quantity into an electrical quantity) Eg. LVDT (mechanical displacement to electrical), Thermocouple (Temp to voltage) 6. Inverse Transducer (an electrical quantity into a non-electrical quantity) E.g., Piezoelectric crystals  7. Primary and secondary Transducer  E.g. For pressure measurement, a bourden tube is used, which is used to convert pressure to displacement. After, LVDT ...