PTC-Cu Heat Sensor & Its Application in Inverter s Thermal Testing

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1 2015; 1(11): ISSN Print: ISSN Online: Impact Factor: 5.2 IJAR 2015; 1(11): Received: Accepted: Er. Pal Riya Bipradas Sanchita ME Research Student [Power Devices], Dept. Of ETRX, PIIT Engineering College, Mumbai University, India. PTC-Cu Heat Sensor & Its Application in Inverter s Thermal Testing Er. Pal Riya Bipradas Sanchita Abstract Dynamic thermal management techniques require accurate runtime temperature information in order to operate effectively and efficiently. In this paper, unique sensor construction is illustrated along with its application in HVHC device s thermal detection such as an Inverter. Keywords: Positive Temperature Coefficient (PTC), Copper (Cu), Resistance Temperature Detector (RTD), Temperature coefficient (α). 1. Introduction 1.1 Resistance Temperature Detector(s) (RTDs) Resistance Temperature Detectors (RTD), as the name implies, are sensors used to measure temperature by correlating the resistance of the RTD element with temperature. RTDs are relatively immune to electrical noise and therefore well suited for temperature measurement in industrial environments, especially around motors, generators and other high voltage equipment. Correspondence Er. Pal Riya Bipradas Sanchita ME Research Student [Power Devices], Dept. Of ETRX, PIIT Engineering College, Mumbai University, India. Fig 1: Basic RTD diagram RTD Types (available in the market): Pt 100, 200, 500, 1000 etc. ~ 336 ~

2 Element size (MI): 1. Wire wound ceramic encapsulated. 1.2 Positive Temperature Coefficient Resistor (PTC) A positive temperature coefficient (PTC) refers to materials that experience an increase in electrical resistance when their temperature is raised. Materials which have useful engineering applications usually show a relatively rapid increase with temperature, i.e. a higher coefficient. The higher the coefficient, the greater an increase in electrical resistance for a given temperature increase. A PTC material can be designed to reach a maximum temperature for a given input voltage, since at some point any further increase in temperature would be met with greater electrical resistance. Unlike linear resistance heating or NTC materials, PTC materials are inherently self-limiting. Fig 2: Wire wound ceramic encapsulation 2. Thin film ceramic encapsulated Fig 6: Behavior of PTC & NTC w.r.t Temperature Fig 3: Thin film ceramic encapsulated 3. Wire wound glass encapsulated A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property R that changes by dr when the temperature changes by dt, The temperature coefficient α is given by: = α dt Table 1: Aof Certain Elements Connections: 2, 3, 4 wired Fig 4: Wire wound glass encapsulated α Nickel Molybdenum Tungsten Iron Aluminum Copper Silver Gold Platinum Resistance values for conductors at any temperature other than the standard temperature (usually specified at 20 Celsius) must be determined through yet another formula: R = R ref [1+ α(t-t ref)] Fig 5: Showing 2, 3 & 4 wired RTDs ~ 337 ~ Where R = Conductor s resistance at temperature T 0 C. R ref = Conductor s resistance at reference temperature T 0 C (usually at room temperature). T ref = Reference temperature for which α is specified for the conductor. α = Temperature coefficient of resistance for the conductor material.

3 2. Ptc-Cu Based Temperature Sensor Constructed A new PTC-Cu based temperature/heat sensor has been constructed. It is possible to measure temperature/heat of above C using this PTC-Cu sensor. PTC & Cu both of them are joined with cyanoacrylate ester in a suitable solvent like acetone, nitromethane. Fig 7: PTC-Cu based Heat/Thermal sensor 3. Testing: Experimental Setup Since PTC has been used, the sensor s resistance will increase with increase in the temperature/heat being sensed. But practically, slight fluctuation in the resistance value will happen. Simple experiment was conducted where temperature of water was increased linearly as shown in figure number 8. Fig 8: Experimental setup ~ 338 ~

4 4. Calculations Table 2: Data Sheet Ploted during the Experiment TEMPERATURE T ( 0 C) RESISTANCE R (KΩ) T (in 0 C) R (in KΩ) = = = = = = = = = = = = = = = = = = = = = = = = = = = = Avg Temperature value calculation: (1X14) / 15 = C Avg Resistance value calculation: ( R) / 15 = 2.8kΩ/15 = kω 1 0 C = /0.933 = 0.2 kω 1 0 C = 0.2 kω (1) 5. Application of Ptc-Cu Based Heat Sensor PTC-Cu sensor was used to test inverter s temperature which has been presented in this paper. Digital Heat sensors/indicators or mercury thermometers are not suitable to measure temperature above C. Basically in thermal management in both mechanical field and electronics field, run time temperature data/ information need to be obtained accurately as well as efficiently. Fluctuations noted in PTC- Cu based sensor is very negligible. Exact resistance value reading at a specific temperature value is indicated via multimeter connected to the extended wires of this sensor. Ω value fluctuation seen on the multimeter is very less. In inverter s temperature sensing application, 5 PTC-Cu sensors were used to measure temperature of aluminum heat sinks located at 5 heat source locations within the inverter. Fig 9: heat locations within the inverter Fig 10: indicating locations where 5 PTC-Cu sensors are placed. Table 3: Inverter s Thermal Reading Taken At 5 Heat Source LoaScations Located Within The Inverter Where Aluminum Heat Sinks Are Attached To Provide Cooling Mechanism Time Sensor 1 Temp T1 Sensor2 Temp T2 Sensor3 Temp T3 Sensor4 Temp T4 Sensor5 Temp T5 (min) S1 in KΩ in 0 C S2 in KΩ in 0 C S3 in KΩ in 0 C S4 in KΩ in 0 C S5 in KΩ in 0 C Initial T1, T2, T3, T4 & T5 are calculated from the data obtained in equation 1. ~ 339 ~

5 Fig 11: Shows the photographic proof of the Table No. 3 plotted above where measurement was taken at time (t) = 20min Above TABLE 3 was plotted where 1fan was used as the inverter s load. Full load supported by this specific inverter includes: 4 fans, 1 TV & 1PC 6. Conclusion In this paper a newly developed PTC-C u heat/sensor has been proposed. Because of copper strip acting as a heat conductor (i.e sensor), this device/sensor is capable of measuring heat in thermal management application field where temperature goes beyond C and also to afford multiple sensors (digital or metallic) goes beyond the cost constraint. Here, through this research paper, it has been illustrated how to use PTC-Cu sensor to measure inverter s temperature if one is carrying out thermal management study on HVHC inverter. 7. References 1. Snuti Kumari, Garima Rathi, Priyanka Attri, Manee Kumar, Types Of Sensors and Their Applications, International Journal of Engineering Research and Development, 2014; 10(4): Fig 12: Load 1FAN being run by the inverter. ~ 340 ~

6 Author Er. Pal Riya Bipradas Sanchita received Bachelor of Engineering in Electronics from PIIT (Pillai Institute of Information Technology, Engineering, Media Studies & Research) under Mumbai University in Currently pursuing Master of Engineering. Her research areas are Power Electronics and Optical Communication. She is the author of (1) Free Space Light Communication. (2) Negative Role of Atmosphere on Free Space Light Communication. (3) Heat in Electronic Circuits and Material Selection Criteria for Cooling Solutions, (4) Measure Of Heat Conduction Through Copper. (5) HY510 Grease: Maximum Temperature Support and Its Application in Cob Led Heat Management. She has designed Electronics PCB project for HPST POWER COMPANY in KBR. ~ 341 ~