Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 Paper

Electrical Machine-I 4TH SEM DIPLOMA PSBTE MAY 2018 PAPER

Duration : 3 Hrs M.Marks : 75

SECTION A

1. Fill in the blanks :

As the load increases, the speed of DC series motor will Decreases
For step-up transformer, the transformation ratio is More then Unity.
Brushes of DC machines are made up of Carbon.
Wave winding has Two Parallel paths.
Working principle of a transformer is Faraday\’s Law of Electromagnetic Induction.
The ratio of KW to KVA is known as Power Factor.
A transformer has no Core and Copper Losses.
Silicon steel is used to reduce Eddy Current Losses.
Transformer will give maximum efficiency when copper losses are equal to Iron Losses.
The shaft of DC machine is made up of mild Steel.

SECTION-B

Q2. Attempt any five questions. 5×6=30

Explain why DC series motor cannot be started without load?
What are the applications of DC motors ?
Explain how electromagnetic torque is developed in DC Motors.?
Name various methods of cooling transformers. Explain any one in Details ?
Explain the speed control methods of DC shunt Motor ?
Following data is obtained on a 5KVA 220/440V,1-Ф transformer

Open circuit test: 220V, 2A, 100W on LV side

Short circuit test: 40V, 11.4A, 200W on HV side. Determine full load efficiency at 0.9pf.

7.Derive e.m.f equation of a Transformer ?

SECTION-C

Q3. Attempt any three questions. 3×10=30

Why is there necessity of a starter? Name different types starters used in dc motors. Explain working of 3 point starter with
Write a note on: a) Parallel operation of transformers b) Auto transformer
Explain various types of losses occurring in DC Machines ?
The armature of a 12 pole DC shunt generator has 50 slots and is wave wound with 12 conductors per slot. The generator is running at a speed of 625rpm and supplies a resistive load of 115ohm at a terminal voltage of 300V, the armature resistance is 0.5ohm and field resistance is 60ohm. Find armature current, generated e.m.f. and flux per Pole ?
Explain various types of DC machines on basis of different types of excitations.

Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 Paper

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Section a :-Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 Paperem
Exam ECE/CSE/IT/EEE/0064/Nov 2015

As the load increases, the speed of DC series motor will ________

As the load increases, the speed of DC series motor will Decreases

For step-up transformer, the transformation ratio is ______ then Unity.

For step-up transformer, the transformation ratio is More then Unity.

Brushes of DC machines are made up of _________.

Brushes of DC machines are made up of Carbon.

Wave winding has _____ Parallel paths.

Wave winding has Two Parallel paths.

Working principle of a transformer is __________.

Working principle of a transformer is Faraday’s Law of Electromagnetic Induction.

The ratio of KW to KVA is known as ________.

The ratio of KW to KVA is known as Power Factor.

A transformer has no _________ Losses.

A transformer has no Core and Copper Losses.

Silicon steel is used to reduce _______.

Silicon steel is used to reduce Eddy Current Losses.

Transformer will give maximum efficiency when copper losses are equal to _____

Transformer will give maximum efficiency when copper losses are equal to Iron Losses.

The shaft of DC machine is made up of ______.

The shaft of DC machine is made up of mild Steel

Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 PSBTE Diploma Solved Paper.Click Here

Section B :Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 Paper

Explain why DC series motor cannot be started without load?

why DC series motor cannot be started without load

What are the applications of DC motors ?

applications of DC motors

Explain how electromagnetic torque is developed in DC Motors ?

How electromagnetic torque is developed in DC Motors

Name various methods of cooling transformers. Explain any one in Details ?

Various methods of cooling transformers.

Explain the speed control methods of DC shunt Motor ?

speed control methods of DC shunt Motor

Following data is obtained on a 5KVA 220/440V,1-Ф transformer

Open circuit test: 220V, 2A, 100W on LV side

Short circuit test: 40V, 11.4A, 200W on HV side. Determine full load efficiency at 0.9pf.

Derive e.m.f equation of a Transformer ?

e.m.f equation of a Transformer

Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 Paper Click Here

Electrical Machines-I 4th Sem EE/EEE/2520/May 2018 Paper

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