8/9/2019 Instrumentation Poster

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TRANSFORMER OIL TEMPERATURE MONITORMidion Kashi r i

EDITH COWEN UNIVERSITY 

INTRODUCTION

Oil temperature monitoring system block diagram

DESCRIPTION

THE SENSOR, ACTUATOR AND DATA AQUISATION

The rating of a transformer is based on the temperature rise above anassumed maximum ambient temperature. The transformer should be capableof continuous operation at rated power without exceeding the maximumtemperature-rise limits as specified by the manufacturer or applicablestandards.

 According to ABB, a renowned transformer manufacturer, the winding mustnot overheat; a temperature of about 85°C is considered to be the normalmaximum working value beyond which a further rise of 10°C-15°C, ifsustained, will halve the insulation life of the transformer. Protection againstoverload is therefore based on winding temperature, which is usuallymeasured by a thermal image technique. The windings are immersed in oil tocool and insulate them. Monitoring the oil temperature gives us an awarenessof any temperature changes in the windings.

 At a temperature of 85°C our monitoring system should give us an alarm orturn on some cooling fans. If the temperature continues to rise above 100°Cthe transformer should be disconnected from the power supply. to rise, thetransformer should be disconnected by sending a tripping signal to both theprimary and the secondary side protection breakers when the temperaturereaches 100°C.

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Power transformers heat up when they are in operation and hightemperatures reduce the operating parameters of the transformer. This

project demonstrates how a computer controlled system can monitorthe temperature of a power transformer. The temperature monitoring

system consists of a sensing device, signal conditioning circuitry, data

acquisition hardware, an actuator and the software.

Our sensing device is an NTC Bosch Thermistor part number 0 280 130 026which has a measurement range of -40 to +130°C.. In practice the actuatorshould be very large 3 phase AC cooling fans w hich are difficult to demonstratewith in the lab because of safety and the availability of the required powersupply. Therefore to simulate our project, we will use a small lab fan and if thetemperature continues to rise above 100°C we should have a voltmeter readingof +0.285v across the transformer breaker trip circuit terminals

We used DLP-IO8 Data Acquisition Module, for this project. It is designed formeasuring voltages, controlling and monitoring processes, and acquiringtemperature data. Each of the 8 available channels can be configured for any ofthe digital, analog, or temperature modes via single-byte commands. It is a 5-voltsystem that derives its power from the host USB port..

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