Report Equips

7/25/2019 Report Equips

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Lopez, Paul AvryMagaan, Bryan Dave Docto

Pundal, Eduardo Mon

Designations, Model Number Systems and Bearing Inormation or !arious Manuacturers"

Electrical E#uipment$Identiication and Bearing Inormation, IP %ode or &otating Electrical Mac'ine, Data %odes, (ypes o

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Synchronous Motor

Asynchronouselectric motor is an AC motor at

steady state, the rotation of the shaft/rotor issynchronized with the frequency of the supply

current; the rotor is excited by a dc power supply or

can be also a permanent magnet.


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Synchronous Motor General Maintenance

Varnishing of Machine WindingsWinding failure caused by vibration of coils during operationMachine operation

at higher temperature than normal, shortens life of insulation

a. Coat all insulated surfaces of the brush holders and slip rings with a

high-gloss insulating varnish.

b. Periodic varnish treatment and curing, correctly done so as to fill all spacescaused by drying and shrinkage of the insulation, will provide an effective

seal against moisture and should be a matter of routine electrical maintenance.

During Overhaul

Nuts on the studs or wedges of dove tail poles should be checked for looseness

If the collector rings become eccentric, grooved, pitted, or deeply scratched,

this condition can best be corrected by grinding the rings with a rotating-type

grinder, with the machine running at rated speed in its own bearing.

Electrical Power Equipment and Testing by Paul Gill 2ndEd. CRC Press


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Cleaning

Carbon black, metallic dust and chips form a conductive film over the insulation

and increase the possibility of insulation failure.

a. Dirt should be removed from all coil surfaces and mechanical parts. Air ventducts should be clear.

b. As much oil, grease, and dirt as possible should be removed by wiping the

windings with clean, dry cloths and then with clean cloths that have been

moistened with a solvent recommended by the coil manufacturer.

c. For cleaning, armatures or wound rotors should be placed in a vertical positionwith the commutator or collector ring end up, and a pressure spray gun with

solvent should be used to clean under the collecting device and through vent

holes.

d. Dust in collector rings and brush holder should be blown off weekly with dry

air.

Lubrication

Excess oil collect dust, too much grease in anti-friction bearing causes heat.

Electrical Power Equipment and Testing by Paul Gill 2ndEd. CRC Press

In all cases, a lubricant should be applied to the shaft or to the sealing element of

the oil seal. This aids installation and reduces heat buildup during the first few

minutes of run. The application of a lubricant to the outer periphery of a

synthetic rubber-covered seal will reduce the possibility of shearing or bruising.


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Alternator

Is an electrical generator that

converts mechanical energy toelectrical energy in the form

of alternating current.


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AlternatorPar

tsSmallAlternator


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WoundStationaryArmature

Stator- Rotates

Armature-Stationary

Most preferable

1. Armature winding is more complex than the field and can be

constructed more easily.

2. The armature winding can braced more securely in a rigid frame.

3. It is easier to insulate and protect high-voltage armature winding.

4. The armature winding is cooled more rapidly because the stator core

can be made large enough for forced air circulation.

5. The low voltage field can be constructed for efficient high-speed

operation.


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An inductionor asynchronous motor isan AC electric motor in which the electriccurrent in the rotor needed to producetorque is obtained by electromagneticinduction from the magnetic eld of the

stator winding.

INDUCTIN!T"


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Electrical Power Equipment and Testingby Paul Gill2nd

Ed. CRC Press.

Air Gap

If air gap is affected by grinding the rotor laminations or filing the stator teethresults in increase in magnetization current and lower PF.

The air gap should be periodically checked with a feeler gauge to ensure against

a worn bearing that might permit the rotor to rub against the stator core. Even

slight rubbing of the rotor against the stator will generate enough heat to

destroy the coil insulation.

Brushes and Rings

Rough or uneven ring surfaces should be remedied as soon as possible, before

sparing, pitting, and accelerated brush wear result. Allowing the rotor to

oscillate axially will distribute wear more evenly. Unevenly worn brushes should

be replaced to assure best operation.


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Squirrel-Cage Rotors

Squirrel-cage rotors are more rugged and, in general, require less maintenance

than wound rotors. Open circuits or high-resistance joints betweenthe end rings

and the rotor bars may give trouble. The symptoms of such conditions are

generally the same as with wound-rotor motors, that is, slowingdown underload

and reduced starting torque. Look for evidence of heating at the end ring

connections, particularly when shifting down after operating under load.

Stator Windings

A regular schedule of inspection can prevent costly shutdowns and repairs by

revealing small defects, which can be corrected before they develop into serious

faults. The operating temperature of the machine should be checked a regular

intervals. Open-type machines must be inspected more frequently than closed

types, with the machines shutdown if possible.

The best way to evaluate the condition of insulation is to measure the insulation

resistance at regular intervals when the machine is hot. A sudden decrease in


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the insulation resistance may indicate an approaching breakdown, which may

be avoided if the cause is located and corrected in time.


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Wound-Rotor Windings

Most wound rotors have a three-phase winding and are susceptible to trouble

from single-phase operation and open circuits. The first symptoms of these

faults are lack of torque, slowing down in speed, growling noise, or perhaps

failure to start the load.

The first place to look for an open secondary circuit is in the resistance or the

control circuit external to the rotor. Short-circuiting the rotor circuit at the slip

rings and then operating the motor will usually determine that the trouble is inthe control circuit or in the rotor itself.

Another fairly successful method of checking for short circuits in the rotor

windings is to raise the brushes off the collector rings and energize the stator. A

rotor winding that is free from short circuits should have little or no tendency to

rotate, even when disconnected from the load. If there is evidence of

considerable torque or a tendency to come up to speed, the rotor should be

removed and thewinding opened and examined for the fault.


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1. Work done per unit of time

2. Voltage rating at which the

motor is designed to operate

most efficiently.

3. Full Load Amps is the amount

of current the motor can be

expected to draw under full load

conditions.

4. The speed at which full-load

torque is delivered for the ratedvoltage and frequency.

5. Motor dimension standardization

is reflected by the frame size

number, Frequency and the type of

power supply.6. Service Factor is an indicator of

the amount of overload a motor can

be expected to handle.

7. The percentage of the input

power that is actually converted towork outut from the motor shaft

NAMEPLATEINFORMATION

1.

2.

3.4.

5.

6.

7.


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NEMA design A

maximum 5% slip

high to mediumstarting current

normal locked rotor

torque

normal break

down torque suited for a broad

variety of applications

asfans and pumps

NEMA design C

maximum 5%slip

low starting current high locked rotor

torque

normal breakdown

torque

suited for equipmentwith high inertia

starts -aspositive

displacement

pumps

NEMA design B

maximum 5%slip

low starting current high locked rotor

torque

normal breakdown

torque

suited for abroadvariety of applications,

normal starting torque-

common inHVAC

application with fans,

blowers and pumps

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