# Difference Between Current Transformer and potential transformer

Today we Are discuss the Difference Between Current Transformer and potential transformer. The current transformer measures current and potential transformer Measure voltage. A current transformer is similar in construction to a power transformer that it has a magnetic circuit with a primary and a secondary winding, There is a considerable difference in the method of operation.

• In a potential transformer, the primary winding is continuously energized at a substantially constant voltage, and the secondary is connected to a load varying in impedance within wide limits. The current in the primary winding is determined by the load connected to the secondary. The magnetic flux in the core is substantially constant at all loads.

• The current transformer is connected in the line in series with the load. The load determines the current through the primary. The secondary is connected to a load or burden which does not vary, and the primary current is not affected by the load in the secondary. The current in the secondary is determined by the current in the primary. The magnetic flux in the core varies, with the current in the primary. The flux is determined by the connected burden. The flux density in the core is only a very small fraction of that usually used in a power transformer.

### Limitations of Terzaghi Theory

Limitations of Terzaghi Theory The value of the coefficient of consolidation has been assumed to be constant.  The distance d of the drainage path cannot be measured accurately in the field. The thickness of the deposit is generally variable, and an average value has to be estimated.  There is sometimes difficulty 1n locating the drainage face, sometimes thin previous seams that can act as good drainage face are missed in the boring operations. The equation is based on the assumption that the consolidation is one-dimensional. In the field, the consolidation is generally 3-dimensional. The lateral drainage may have a significant effect on the time rate of consolidation. The initial consolidation and secondary consolidation have been neglected. Sometimes these form an important part of the total consolidation. In actual practice, the pressure distribution may be far from linear or uniform. Read More Muller-Breslau principle

### Price Guard Wire Method

Price Guard Wire Method Some form of  Price Guard Wire Method  is generally used to eliminate the errors caused by leakage currents over insulation. Fig. 3.14 illustrates the operation of This Method. In fig 3.14(a), a high resistance mounted on a piece of insulating material is measured by the ammeter voltmeter method. The micro-ammeter measures the sum of the current through the resistor (IR) and the current through the leakage path around the resistor. The measured value of resistance computed from the readings indicated on the voltmeter and the microammeter, will not be a true value but will be in error.   Figure 3.14 Application of  guard  circuit for measurement of high resistance In fig, 3.14 (b), the  guard  terminal has been added to the resistance terminal block. The  guard  terminal surrounds the resistance terminal entirely and is connected to the battery side of the micro-ammeter. The leakage current IL now

### Streamer Theory of Breakdown in Gases

Streamer Theory of Breakdown in Gases According to the Townsend theory firstly, current growth occurs as a result of the ionization process only. But in practice, breakdown voltages were found to depend on the gas pressure and the geometry of the gap. Second chances time lags of the order of 10-5 s, but practically it was observed to occur at a very short time of 10-8 s. Also, the Townsend mechanism predicts a very diffused form of discharge, that actually discharges were found to be filamentary and irregular. Townsend's mechanism failed to explain all these observed phenomena and as a result, The Streamer theory was proposed. The theory predicts the development of a spark discharge directly from a single avalanche in which the space charge developed by the avalanche itself is said to transform the avalanche into a plasma steamer. In Fig 1.7, a single electron starting at the cathode by ionization builds up an avalanche that crosses the gap. The electrons in the a