Topic Assessment 4 Transformer Losses, Efficiency and Cooling (60 min)_ Attempt review.pdf

Dashboard / My courses / EL25 - Test and connect transformers / Topic Assessments / Topic Assessment 4 Transformer Losses, Efficiency and Cooling (60 min) Started on Thursday, 8 August 2024, 4:06 PM State Finished Completed on Thursday,...

Dashboard / My courses / EL25 - Test and connect transformers / Topic Assessments / Topic Assessment 4 Transformer Losses, Efficiency and Cooling (60 min) Started on Thursday, 8 August 2024, 4:06 PM State Finished Completed on Thursday, 8 August 2024, 4:10 PM Time taken 3 mins 48 secs Marks 12.00/12.00 Grade 100.00 out of 100.00 Feedback Congratulations you have achieved 100%. Good luck with your continued studies. Question 1 Correct Mark 4.00 out of 4.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 1 What are FOUR desirable characteristics of transformer cooling mediums? Select one or more: High resistance to emulsion in order to prevent the holding of moisture in suspension in the fluid High viscosity to enable slower circulation of the fluid and dissipation of heat Low resistance to emulsion in order to hold moisture in suspension in the fluid Low dielectric strength to increase the insulation distances from the walls of the tank High dielectric strength to reduce the insulation distances from the walls of the tank Does not form sludge under normal operating conditions Forms sludge under normal operating conditions for additional cooling properties Low viscosity to enable rapid circulation of the fluid and dissipation of heat Your answer is correct. Question 2 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 2 Match the correct acronym for each cooling method description: Description Acronym AN A method of cooling a transformer where natural air circulation is used  A transformer with a high current application that uses a heat exchanger to transfer heat from transformer oil ONWF to cooling water  ONAF A transformer that uses fans to increase the effectiveness of natural air to cool the transformer  Your answer is correct. Question 3 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 3 As well as cooling, what other role does transformer oil play? Select one: Prevents transformer lamination mains hum Forms part of the transformer insulation system Power factor correction Lubricates the windings Your answer is correct. Question 4 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 4 Review the statement/s carefully and indicate True or False. Statement True/False Two power losses in a transformer are iron losses and excitation losses False  Your answer is correct. Question 5 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 5 In identifying iron losses and copper losses, which two tests are required? Select one: Iron Loss - short circuit Copper Loss - open circuit Iron Loss - open circuit Copper Loss - open circuit Iron Loss - short circuit Copper Loss - short circuit Iron Loss - open circuit  Copper Loss - short circuit Your answer is correct. Question 6 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 6 When the efficiency of a transformer (at a specific power factor), is at maximum, what are copper losses? Select one: Equal to iron losses  At a minimum Higher than our hysteresis At a maximum Your answer is correct. Question 7 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 7 To calculate the efficiency of a transformer, which of the following formulas would be most useful? Select one: p = ((Pout + Losses) / Pin) x 100 n% = ((Pout - Losses) / Pin) x 100 n% = ((Pin - Losses) / Pin) x 100 eff = ((Pout + Losses) / Pin) x 100 Your answer is correct. Question 8 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 8 Calculate the efficiency of the transformer when a 10KVA transformer has total loses of 450 watts: Select one: 4.5% 95.29% 104.5% 95.7%  Your answer is correct. Question 9 Correct Mark 1.00 out of 1.00 Topic Assessment 4 Transformer Losses, Efficiency and Cooling Question 9 What is the increase of the kVA rating of the transformer when auxiliary equipment such as pumps or fans are used to cool the transformer? Select one: More than double Up to half Up to three quarters Up to one third Your answer is correct. ◄ Topic Assessment 3 Transformer Operation (60 min) Jump to... Topic Assessment 5 Transformer Voltage Regulation (60 min) ►