Knowledge is power essay

  The electrical instruments are not directly connected to the meters or control apparatus of high voltage for safety purpose. The instrument transformers like voltage transformer and current transformer are used for connecting the electrical instruments to the measuring instruments.These transformers reduce the voltage and current from high value to the low value which can be measured by conventional instruments. The construction of the current and potential transformer is similar as both have the magnetic circuit in their primary and secondary winding. But they are different in the method of working. There are several types of differences between the voltage and the current transformer. One of the major difference between them is that the current transformer converts the high value of current into low value whereas the potential or voltage transformer converts the high value of voltages into low voltage. Some other differences between the current and the potential transformer are...

Minimum Electrical Clearance As Per BS:162. INDOOR Voltage in KV Phase to earth in mm Phase to phase in mm 0.415 15.8 19.05 0.600 19.05 19.05 3.3 50.8 50.8 6.6 63.5 88.9 11 76.2 127.0 15 101.6 165.1 22 139.7 241.3 33 222.25 355.6 Minimum Electrical Clearance As Per BS:162. OUTDOOR Voltage in KV Phase to earth in mm Phase to phase in mm 6.6 139.7 177.8 11 177.8 228.6 22 279.4 330.2 33 381 431.8 66 685.8 787.4 110 863.6 990.6 132 1066.8 1219.2 220 1778 2057.4   Minimum Working Clearance: OUTDOOR SWITCHYARD Voltage in KV To ground in mm Between section(mm) 11 2750 2500 33 3700 2800 66 4000 3000 132 4600 3500 220 5500 4500   Minimum Ground Clearance As Per IE-1956(Rule 77) Voltage in KV To ground in mtr 132 6.10 220 7.00 400 8.84 800 12.40     Minimum Clearance between Lines Crossing Each Other (IE-1957) System Voltage 132KV 220KV 400KV 800KV Low & Medium 3.05 4.58 5.49 7.94 11-66KV 3.05 4.58 5.49 7.94 132KV 3.05 4.58 5.49 7.94 220KV 4.58 4.58 5.49 7.94 400KV 5.49 5....

Introduction of Efficiency of Transformer Transformers form the most important link between supply systems and load. Transformer’s efficiency directly affects its performance and aging. The transformer’s efficiency, in general, is in the range of 95 – 99 %. For large power transformers with very low losses, the efficiency can be as high as 99.7%. The input and output measurements of a transformer are not done under loaded conditions as the wattmeter readings inevitably suffer errors of 1 – 2%. So for the purpose of efficiency calculations, OC and SC tests are used to calculate rated core and winding losses in the transformer. The core losses depend on the transformer rated voltage, and the copper losses depend on the currents through the transformer primary and secondary windings. Hence transformer efficiency is of prime importance to operate it under constant voltage and frequency conditions. The rise in the temperature of the transformer due to heat generated affects the life of ...

Single Phase Transformer Full-Load Current (Amps)= kVA × 1000 / V Three Phase Transformer Full-Load Current (Amps) = kVA × 1000 / (1.732 × V) Where: kVA  = transformer rating (kilovolt-amperes), V  = voltage (volts).   Turns Ratio = N 1  / N 2  = V 1  / V 2  = I 2  / I 1 Where: N 1  = number of turns on the primary, N 2  = number of turns on the secondary, V 1  = primary voltage, V 2  = secondary voltage, I 1  = primary current, I 2  = secondary current.   Example:  A 50 kVA single-phase transformer has a 4000 V primary, and a 400 V secondary. Assuming an ideal transformer, determine (a) the primary and secondary full-load currents, (b) the transformer turns ratio. a)  V 1  = 4000 V, V 2  = 400 V, Transformer Rating = 50 kVA = V 1  × I 1  = V 2  × I 2 Primary full-load current, I 1  = (50 × 1000 / 4000) = 12.5 A Secondary full-load current, I 2  = (50 × 1000 / 400) = 1...