2.3 Application Assignment

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School

Defense Acquisition University *

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Course

EET390

Subject

Electrical Engineering

Date

Jan 9, 2024

Type

docx

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Uploaded by charleshaskett

2.3 Application Assignment A dry-type general-purpose power transformer is observed to be operating above its rated temperature. What are some possible causes? Possible causes for the dry-type general purpose transformer to be operating above the rated temperature are: An over voltage is being applied to transformer. The transformer is being loaded at a greater kVA than the nameplate kVA rating. The ambient air is higher than recommended (30C average / 40C maximum). The transformers enclosure ventilation openings are either obstructed or there is a high content of dust and/or lint in transformer air ducts. The load attached to the transformer contains large amount of harmonics. A local fire department responded to an automatic trouble call at a large office building. Unable to determine which breaker controlled which branch circuit, the fire chief issued an order to open all of the breakers. This put two floors of the building in the dark, rather than just the one room in question. How could this unnecessary interruption in operation be prevented? The unnecessary interruption could have been prevented if the circuit breakers were properly labeled or tagged with the location that particular circuit breaker was supporting/serving. Another way is to ensure that any electrical drawing showing the connections of the circuit breakers and to the areas that are connected to them. Having properly labeled circuit breakers and electrical drawings allow for a speedy identification of what circuit breakers would have needed to be disconnected without unnecessarily affecting other parts of the building. References Petruzella, F. (2019). Electric Motors and Control Systems (3rd ed.). McGraw-Hill Higher Education (US). https://ecpi.vitalsource.com/books/9781260439588 Technik, E. (2010, April). What are the reasons for transformer Overheating? Retrieved from ELECTROTECHNIK: https://www.electrotechnik.net/2010/04/what-are-reasons-for- transformer.html

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