So the expression for transformer regulation is. % regulation = No-load Voltage – Full load voltage/ full load voltage * 100; Under no load condition the induced voltage E2 is presented at the output terminals and when the transformer is loaded due to drop across the reactance it changes to V2. Answer: 1. Figure shows the arrangement of CT where the primary conductor carrying current induces the magnetic flux in secondary turns to produce the respective turns. In low voltage winding the current flowing is high compared to high voltage winding ad hence I2R (core losses) losses are high which produces high heat. Because as the frequency decreases the flux increase for a constant voltage. A. Buchholz relay is a device which is used for the protection of transformer from its internal faults, it is a gas based relay. Answer : Transformer substation, Converting substation, Frequency substation, Switching substation, Power factor correction substation, Industrial substation. Frequent exposure to Lightning strokes. (a) Current (b) Voltage (c) Frequency (d) All of the above Ans: c. 2. Transformer regulation is defined as the percentage change in output voltage from no-load to full load with respect to full load. When a load is connected to a transformer current (say I 2) flows through secondary coil thus an M.M.F (N 2 I 2) is produced, this produces the secondary flux. in primary side the varying current produces a varying magnetic field (electromagnetism) and this magnetic flux lines are cut by the adjacent secondary coil (induction principle) and EMF will be induced. Top 100 Switchgear and Protection Interview Questions. The accuracy should be high for Instrument transformers where as in protection it can be somewhat less. Normally primary winding will be single wire and secondary will be many turns so the secondary measuring current will be less. Three sets of primary and secondary windings which are connected in Delta or Star arrangement. According to the construction type of transformers the following protectionsmust be provided: Oil-filled transformers with conservator 1. 11. Buchholz Relay in Transformer… Transformer oil functions as a coolant as well as insulating material. Posts about electrical interview questions on transformer written by electricalsafetytestinglab Electrical Safety Testing Lab ITCIndia Electrical Safety Testing Laboratory provide LED Light, Photometric LM 79, IP dust & water ingress protection, Machinery Safety, Testing. Dear Readers, Welcome to Transformer Protection Interview Questions and Answers have been designed specially to get you acquainted with the nature of questions you may encounter during your Job interview for the subject of Transformer Protection.These Transformer Protection Questions are very important for campus placement test … What Are The Classifications Of The Substations According To Its Functions? Instrument transformer is used to measure the signal parameters (voltage and current) to indicate in the meters (voltage and current) where as protection transformer measuring signal is used for relay operation for protection of transformer. Q. Transformer Interview Questions [34m75xm7op46]. During line to ground faults, grounding of neutral helps to reduce the over-voltages which occur on the onehealthy phases. For example ONAF indicates that it is Oil Natural and Air Forced type cooling. Like as in step up transformer the voltage is stepped up i.e. The high voltage winding is wounded over low voltage winding and accessing of that winding is easy compared to low voltage winding. Isolating transformer: This transformer is used to provide isolation between primary and secondary to protect the winding from the faults. Also using laminated cores especially, thinner core laminations can help in achieving better transformer efficiency by reducing core losses. H.V rating (21KV): This is the maximum high voltage side voltage with it can withstand. Electric Shock | How Does human body get electric shock Ferrite Core On Cable | Why Ferrite Core | Working Principle How Does Series Reactor Reduce Harmonic [wp_ad_camp_2] Main Purpose of Damper Winding […] Why high voltage winding is wounded over low voltage winding? What is a transformer? Oil Sample Test: to check the oil quality. Power rating (1000 KVA) : It indicates that the transformer is able to supply 1000 KVA of load without any problem. The output of the CT will be normally 5 or 10 amps. b) Interfacial tension and acid number (sometimes called neutralization number or acidity) are affected by oxidation and contamination. The transformer cannot be operated more than 10% higher than the rated voltage because if the primary is high therefore secondary also increases which leads to increase in power rating of a transformer. 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