Lecture Notes - Motors

8/2/2019 Lecture Notes - Motors

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Typical Motor - Elevation and end view


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1.0 GENERAL

1.1 APPLICATION

1.2 NUMBER OF UNITS

1.3 TYPE OF MOTOR SQUIRREL CAGE/

WOUND ROTOR

1.4 SUPPLY SYSTEM FAULT LEVEL MVA

1.5 SUPPLY NEUTRAL

TYPE OF EARTHING

1.6 COMPLIANCE WITH TCE.M4-

203-02 IS REQUIRED YES/NO

1.7 IF YES CLAUSES OF

TCE.M4-203-02 WHICH ARE

NOT APPLICABLE :

Assignment:

List different applications of cage rotor and wound rotor in a thermal

power plant.

What is the relevance of fault level on motor design and system

grounding


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2.0 RATING

2.1 RATED OUTPUT : kW

2.2 RATED VOLTAGE : V

2.3 NUMBER OF PHASES &

FREQUENCY

Discussion:

Frame size, rotor class, speed of motor

Study the various factors considered while arriving at the motor rating

considering the brake kW calculation (fan / CW pump and Boiler feed

water pump, Lift./ EOT crane).

Assignment:

Study the basis for arriving at standard rating of motors.

What is the relevance of fault level on motor design and system grounding


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Supply ConditionI II

(a) Variation in supply voltagefrom rated voltage +6% +10%

(b) Variation in supply frequencyfrom rated frequency +3% +5%

(c) Combined voltage andfrequency variation 9% 10%

Voltage supply condition


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Assignment:

Study the difference between the V/F curves of Motor and Generator

IEC-34-1


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2.0 RATING

2.4 SUPPLY CONDITION (REF.

CL.NO.4.1 OF TCE.M4-

203-01) I/II

2.5 SYNCHRONOUS SPEED RPM

Effect of voltage variation on Brake kW, Torque and speed

Assignment:

Study the basis for arriving at standard rating of motors.

What is the relevance of fault level on motor design and system grounding

Discussion:

Effect of harmonics


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3.0 DUTY

3.1 TYPE OF DUTY (CLAUSE 9.2

OF IS:325 OR EQUIVALENT)

3.2 POWER REQUIRED BY LOAD kW

Assignment: Find out the duty type of a passenger lift motor and the duty

type of the main lifting motor of a EOT crane


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5.0 INSULATION

5.1 CLASS OF INSULATION

5.2 REF. AMBIENT TEMPERATURE deg.C

5.3 TEMPERATURE RISE OF WINDING

5.3.1 BY THERMOMETER METHOD deg.C

5.3.2 BY WDG RESISTANCE METHOD deg.C

Insulation A E B F H C

Thermal

class 105 120 130 155 180 200

Temp. rise(K) 60 75 80 100 125 135


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6.0 INSTALLATION

6.1 LOCATION Indoor/Outdoor

6.2 HAZARDOUS AREA DIVISION

(IS:5572 OR EQUIVALENT)

6.3 ATMOSPHERE CHEMICAL/DUSTY/SALT

LADEN

7.0 ENCLOSURE

7.1 TYPE OF COOLING (IS 6362)

7.2 DESIGNATION FOR DEGREE OF

PROTECTION (IS 4691)

Discussion:

Flame proof/ Increased safety enclosures

Acoustic enclosure

Hood for reducing the impact of direct solar radiation

Assignment:

What is temperature class as applicable for flame proof / increased safety

Explain the flame proof enclosure design

What is the difference between TEFC and TETV cooling

What is the impact of degree of protection on motor rating and selection

criterion


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8.0 MAIN TERMINAL BOX

8.1 LOCATION AS SEEN FROM NON-

DRIVE END: RIGHT/LEFT

8.2 RATINGS

(a) SHORT TIME

i. CURRENT : kA(RMS)

ii. DURATION : 0.25 SECS.

(b) DYNAMIC : kA(PEAK)

Assignment:

What issues needs to be kept in mind when selecting/ sizing terminal box

What is the relevance of Short time rating on T. Box


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8.3 EXTERNAL CABLE DETAILS

8.3.1 TYPE

8.3. 2 SIZE & NO OF CORES


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MISCELLANEOUS REQUIREMENTS

9.1 SHAFT ORIENTATION : HORIZONTAL/VERTICAL/

HOLLOW VERTICAL

9.2 MOUNTING SYMBOL : (IS:2253

OR EQUIVALENT)

9.5 ROTATION AS SEEN : CLOCKWISE/ANTI-CLOCKWISE

FROM NDE


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9.9 COLOUR SHADES OF PAINT

Assignment:

What is emmisivity factor and what is its relevance?

Explain the painting process of power coating

What paints are preferred for motor application in saline atmosphere?.

Discussion:

What properties should the external paint of a motor have? Bright color or dull color !


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9.11 WHETHER VIBRATION PADS

REQUIRED YES/NO

9.12 TEMPERATURE DETECTORS/

INDICATORS

9.12.1 EMBEDDED TEMPERATURE

DETECTORS FOR WINDING

REQUIRED YES/NO

9.12.2 EMBEDDED TEMPERATURE

DETECTORS FOR BEARINGS

REQUIRED YES/NO

9.12.3 BEARING THERMOMETERS

FOR DRIVING END & NON

DRIVING ENDS REQUIRED YES/NO

9.13 SPACE HEATERS FOR YES/NO

MOTORS REQUIRED


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THREE PHASE INDUCTION MOTORS IS-325

BS-4999

IEC-34

Codes and Standards


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Earth conductor sizes

Assignment:

Can 3.5 / 4 core cablebe used for three phase

motor earthing?.

Advantages

Disadvantages

Restriction on voltage

level


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Salient Design Issues:

Insulated bearings:

For large motors in order to avoid damage

to the NDE bearing (?) the NDE bearing is

mounted on an insulating sleeve. The

insulating sleeve will ensure that eddy

currents in the shaft do not lead to arcing atthe bearing surface while completing the

circuit through ground


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Salient Design Issues:

Energy efficient motors:

Can the no load loss of a motor be reduced, if so how?

Amphorous magnetic material

Lecture Notes - Motors

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