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“Extend the range of AC Ammeter and AC Voltmeter”

 

 

 

Authors:

Shahrukh Tanekhan 1, Shambhudatt Kadam 2, Paras Veer 3, Pratik Jadhav4, Rohit Bansode 5, Adinath Patil6,

1, Lecturer, Electrical Engineering Department, Rajarambapu Institute of Technology, Rajaramnagar

2, 3, 4, 5, 6, Students, Electrical Engineering Department, Rajarambapu Institute of Technology, Rajaramnagar

Abstract:

This report explores the use of Current Transformers (CTs) and Potential Transformers (PTs) to extend the range of standard ammeters and voltmeters, allowing for the safe and accurate measurement of high currents and voltages. Conventional measurement instruments have limited capacity and are unsuitable for direct use in high-voltage or high-current circuits. CTs and PTs address this limitation by stepping down these values, enabling instruments to measure larger electrical quantities indirectly. The CT, placed in series with the load, scales down the current, while the PT, connected across the voltage source, reduces voltage levels. These transformers operate on the principle of electromagnetic induction, with their ratio determining the factor by which current or voltage readings need to be scaled for accurate measurement.

Widely used in power systems, industrial facilities, and high-voltage equipment monitoring, CTs and PTs enhance safety, accuracy, and reliability in electrical measurement, making them indispensable in electrical engineering applications. This report discusses their working principles, applications, and the practical considerations necessary for their effective use. A CT is connected in series with the circuit whose current is to be measured. It reduces high current on the primary side to a smaller, manageable current on the secondary side. Conversely, a PT is installed in parallel with the high-voltage circuit, stepping down high voltages to safe, readable levels. Both CTs and PTs operate on electromagnetic induction principles and utilize primary-to-secondary winding ratios to achieve precise scaling. This scaling factor allows engineers to interpret the reduced current or voltage readings accurately by applying the respective CT or PT ratio. Using CTs and PTs in measurement circuits ensures safety, accuracy, and operational efficiency in high-power applications, such as substations, power distribution, and large- scale industrial setups. The report also examines essential considerations for CT/PT installation, including proper calibration, insulation, and safety protocols. By incorporating these transformers, engineers can reliably monitor and control electrical parameters in high-power systems, contributing to optimized performance and protection of electrical equipment. This report presents the operational principles, connection methods, practical applications, and critical precautions for CTs and PTs, emphasizing their role in expanding the functional capacity of standard measurement instruments.

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