Elements Of Electrical Design — Winter 2019

What are the functions and necessity of a starter for DC and AC motors. State different types of starters used in AC and DC motors.

What is armature winding? Define following terms for it: Turn, Coil,Coil side, Single Layer Winding, Double Layer winding

Draw main circuit and control circuit of star delta starter for 3 phase squirrel cage induction motor.

Prove that the section resistances of DC shunt motor starters are in geometrical progression.

Design a suitable 8 sections starter for a 20 hp, 250 V, 1000 rpm DC shunt motor from the following data: Max. Torque= full load torque, Armature resistance= 0.4, Efficiency=.85%,.

Explain the terms: Field Form Factor, Carter’s Coefficient, Staking Factor, Gap Contraction Factor.

Explain various methods for calculating the mmf required for tapered teeth.

Discuss step by step procedure to design horse shoe type electromagnet for a given supply voltage, required force and stroke.

Name various types of lifting electromagnets commonly used in practice and give comparison between them.

Draw the winding diagram of a DC machine with 4 poles, 14 slots, progressive double layer lap winding. Show the position of brushes.

Explain how the induced emf in stator winding of an AC machine is affected by Pitch Factor and Distribution Factor.

Explain design procedure of small transformer in steps.

Prove that for a given variable choke coil, flux linkages remain constant with constant supply voltage and frequency. Also explain how variable inductance is obtained by varying air gap. State assumptions made if any.

It is required to provide illumination of 120 lumens/m2 in a factory hall 30m*10m . Assume that the depreciation factor is 0.8, coefficient of utilization= 0.5, waste light factor=1.2 and efficacy of lamp is 15 lumens. Calculate number of lamps and their disposition.

What do you mean by service connection. Give its types. Explain any two types.

Which are types of wiring system? Explain any three of them.

Explain with neat sketch power and control circuit of Direct On line Starter.