Use of Instrument Transformers

Use of Instrument Transformers Points : Use of Instrument Transformers The extension of instrument range, so that current, voltage, power and energy can be measured with instruments or meters of moderate size is of very great importance in commercial metering. Here currents and voltages handled are very large and, therefore, direct measurements are not possible as these currents and voltages are far too large for any meter of reasonable size and cost. The solution lies in stepping down these currents and voltages with instrument transformers so That they could be metered with instruments of moderate size. Current being measured by a “C.T.” The primary winding is so connected that the current being measured passes through it and the secondary is connected to an ammeter. The “C.T.” steps down the current to the level of ammeter.

Shows voltage measurement with “P.T.” The primary is connected to the voltage being measured and the secondary, to voltmeter. The “P.T.” steps down the voltage to the level of voltmeter.