The principle of the potential transformer is based on mutual induction. The connection of the power circuit to the voltage transformer is between phase and ground. The primary and secondary winding of the transformer is magnetically coupled through the minimum reluctance path of the core but electrically isolated.
Now, the input of the transformer is given with the high voltage which produces a flux. This flux traverse through the core and induces the voltage at the secondary winding of the transformer. Therefore, through the principle of electromagnetic induction, the high voltage is converted to a lower voltage. This happens without any physical connection between the two. Also, as the potential transformer has a larger value of impedance, therefore, the smaller value of current flows through the secondary winding.
The other function of this transformer is similar to that of the ordinary transformer. The equivalent circuit of the voltage transformer is the same as the ordinary one. The rest of the calculations is the same as for the ordinary transformer. These transformers are categorized based on their function as well as on their construction. Depending on the construction the transformer can be classified as the. Both of these are available in both single-phase and three-phase and have good accuracy.
The use of such transformers is to control and operate measuring devices like relays, etc,. Let us discuss these in detail. This type of potential transformer is similar to the wire wound oil-filled conventional transformers. The tap tank is connected to the line terminal. To fill oil, a plug is there at the tank. It is minted on the insulator support. In this type of PT, the primary winding connects between the two phases. Or between a phase and the ground. Therefore, the one end of the primary is connected to the mains of the measuring power circuit.
And the other to the ground common ground terminal. The secondary of the transformer is given to the load, i. Once the value is calculated at the secondary then with the use of turns ratio, we can calculate the voltage of the higher primary side. The following formula is useful for the calculation:. With the knowledge of all the parameters, we calculate the value of V2. The secondary of this transformer is also useful in the protection of the circuit in case of faults.
Please enter an answer in digits:. Table of Contents. Previous: Electrical consumer unit: Definition, Why is it used? Selection parameters! Leave a Reply Cancel reply Your email address will not be published. Related Stories Types of circuit breakers. Electrical Products. Types of circuit breakers. Types of transformers. Light bulb types. Thermocouple types. The terminal of the transformer should be designed so that the variation of the voltage ratio with load is minimum and the phase shift between the input and output voltage is also minimum.
The primary winding has a large number of turns, and the secondary winding has a much small number of turns. For reducing the leakage reactance, the co-axial winding is used in the potential transformer. The insulation cost is also reduced by dividing the primary winding into the sections which reduced the insulation between the layers.
The potential transformer is connected in parallel with the circuit. The primary windings of the potential transformer are directly connected to the power circuit whose voltage is to be measured.
The secondary terminals of the potential transformer are connected to the measuring instrument like the voltmeter, wattmeter, etc. The secondary windings of the potential transformer are magnetically coupled through the magnetic circuit of the primary windings. The primary terminal of the transformer is rated for V to several thousand volts, and the secondary terminal is always rated for V.
The ratio of the primary voltage to the secondary voltage is termed as transformation ratio or turn ratio. The potential transformer is mainly classified into two types, i. Transformation Ratio. Primary and Secondary Winding. Primary Current. Secondary Side. Input Value. Secondary Winding Range. In a current transformer, the range is 1A or 5A, while in a potential transformer, it is V. Recommend Reading. Post Views: 13, Twitter Youtube Facebook Linkedin.
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