Utility Machinery exam (MDM 301) from BUTEX affiliated colleges' 2023 Level-3 Term-II finals. Questions address transformer tests and flux density numericals, DC generator EMF equations, DC motor torque and voltage relations, and stepper motor types.
Level-3 Term-II, Final Exám-2023
Subject: Utility Machinery (Code: MDM 301)
Time: 3.0 Hrs. Full Marks: 72
(Use separate answer script for Part: A and Part: B)
(All parts of a question must be answered consecutively)
Part: A
(Answer any three questions)
1. (a) State about transformer rating.
(b) Explain open-circuit or no-load test of a transformer.
(c) A single-phase transformer has 400 primary and 1000 secondary turns. The net cross-sectional area of the core is 60 cm². If the primary winding be connected to a 50-Hz supply at 520 V, calculate (i) the peak value of flux density in the core (ii) the voltage induced in the secondary winding.
[2+4+6 = 12]
2. (a) Derive the generated EMF equation of a DC generator.
(b) Explain the working principle of a DC generator.
(c) A 10kW, 250V, d.c., 6-pole shunt generator runs at 1000 r.p.m. when delivering full-load. The armature has 534 lap-connected conductors. Full-load Cu loss is 0.64 kw. The total brush drop is 1 volt. Determine the flux per pole. Neglect shunt current.
[4+4+4 = 12]
3. (a) What is torque? Show that torque power developed of a DC motor, .
(b) Explain the construction and working principle of permanent magnet DC motor.