Marathon SB516 Owner's manual





REEFER Generator



INSTALLATION AND OPERATION MANUAL

260 FRAME SELF REGULATED

BRUSHLESS, SYNCHRONOUS AC GENERATOR



INSTALLATION

AND OPERATION MANUAL

LIMA

®MAC

FRAME

260 SELF VOLTAGE REGULATED

BRUSHLESS, SYNCHRONOUS

AC

GENERATOR

Subject

Safety

Principles

of

Operation

Mechnical Design

Electrical Design

Installation

Electrical Connections

Operation

Maintenance

Service

TABLE

OF

CONTENTS

Page

No.

1

2

2-3

4-5

6-7

8-9

9-

10

10-

15

Trouble Shooting Procedures

16-

18

Parts Lists

Length

Air Filtration

Syatem

Construction

Bearing Features

SB516 3/97

SPECIFICATIONS

17" length over

all.

Side inlet air filtration baffel.

Optional exhaust baffel.

19-21

Cast aluminum frame, Cast iron bearing carrier.

Double sealed

6308 bearing. Chevron SRI #2 grease.

100,000 hours B-10

life.

Integral outer race anti-rotation 0-ring.

INSTALLATION, OPERATION AND MAINTENANCE MANUAL

260

FRAME

Lima"

MAC

17"

REFRIGERATION

DUTY

ALTERNATORS

SAFETY

A

FEW

WORDS

ABOUT

SAFETY

PLEASE

REMEMBER

SAFETY FIRST.

If

you are not sure

of

the instructions

or

procedures

contained herein, seek qualified help before continuing.·

This manual emphasizes the safety precautions necessary during the installation, operation, and

maintenance

of

your Lima" MAC 260 Frame generator. Each section has caution and warning messages.

These messages are for your safety, and the safety

of

the equipment involved.

If

any

of

the cautions or

warnings are not readily understood, seek clarification from qualified personnel before proceeding.

Before any service work

is

done, disconnect

all

power sources and, where appropriate, lock out

all

controls to prevent an unexpected stan-up

of

the generator set driver. Proper grounding ( eanhing)

in

compliance with local and national electrical codes and standards must be provided. These safety

precautions are necessary to prevent potential serious personal injury,

or

even death.

The hazards associated with lifting

or

moving your Lima" MAC generator are pointed

out

in

the

installation and service sections. Incorrect lifting

or

moving can result

in

personal injury

or

damage to

the unit.

Prior to

stan-up

of

the unit insure that

all

generator leads are properly and securely connected to the

terminal strip. Always assume

that

there will be voltage present

at

the

generator

terminals

whenever

the

generator's

shaft

is

rotating,

and

proceed accordingly.

Whenever solvents, cleaners,

or

flammable liquids are present, adequate ventilation must be available

to avoid fire, explosion, and health hazards. Always avoid breathing vapors and use suitable personal

protective equipment to prevent personal injuries.

(Such as head, eyes, face, feet, and hand protection)

This manual

is

not intended to be a substitute for properly trained personnel. Installation and repairs

should only be attempted

by

qualified trained people. The cautions and warnings point out known

conditions and situations that are potentially hazardous. Each installation may well create its own set

of

hazards. No manual can cover every possible situation.

When in doubt, ask. Don't be embarrassed to ask questions. Sincere questions are much easier

to

handle

than mistakes caused by a misunderstanding

of

the information presented

in

this manual.

MECHANICAL DESIGN

General.

Lima" MAC Refrigeration

Duty

alternators are single bearing, self excited,

self

voltage

regulated

240Y/480Y volt three phase,

60

Hertz, single bearing machines designed for the harsh

environmental conditions

of

over-the-road container refrigeration. The generator frame is cast aluminum

alloy, and the bearing carrier

is

cast iron. Bearings

~re

pre-lubricated for life, single width, double sealed

ball bearings conservatively sized

to

give long service life.

Enclosures. The standard generator

is

protected

to

IP 22 (NEMA Dripproof). With the optional Exhaust

Baffie assembly installed, protection is

to

IP 23.

Single

Bearing

Configuration,

260

Frame.

The single bearing 260 frame is available as either a

standard

SAE

#5

or

SAE #4 flywheel housing adaptor integral with the frame. A variety

of

SAE

flywheel

housing adapters and flex disc driving arrangements

are

available and installed at

the

factory to order,

but

can

be changed

in

the field with factory supplied parts. Changing adaptor rings and flexible drive

discs may require the use

if

hub spacers and/or spacer discs

to

maintain

SAE

standard "G" dimensions.

(The

distance from the mating surface

of

the engine's flywheel housing

to

the mating surface

of

the

engine's flywheel) Consult with the factory prior

to

attempting to make a field change in engine adaption.

The specific generator part number, serial number, and adaption kit

part

number (labeled Adpt. Kit) taken

from

the

nameplate

of

the unit will

be

necessary when discussing any engine adaption change with the

factory.

ELECTRICAL DESIGN

General.

The

Lima®

MAC Refrigeration Duty alternator is a

self

excited,

self

voltage regulated

synchronous

AC generator, and does

not

employ an automatic voltage regulator.

The

main

stator

and

exciter stators are housed

in

the generator frame. All rotating electrical components; exciter rotor, main

rotor,

and the rotating rectifier assembly

are

mounted

on

a common shaft. Lima"

MAC

Refrigeration

Duty alternator main stators are

two

circuit,

wye

connected, 10 load lead designs.

Principles

of

Operation.

The exciter stator (stationary winding) and the exciter

rotor

(rotating winding)

are both three phase armature type windings, and are in essence the primary and secondary windings

of

a

rotating

current transformer/frequency converter. The exciter stator is comprised

of

two

separate

windings: a shunt winding and a series winding.

Each

phase

of

the main stator is interconnected with the

shunt winding

of

the exciter stator

to

provide no load excitation.

The

series portion

of

the

exciter

stator

winding is connected

in

series with the main

stator

winding, and thus carries all

of

the

load current

to

provide a compounding excitation characteristic. All main stator/exciter

stator

inter-connecting pairs

of

leads

are

mated with crimp type parallel splice connectors, insulated, and bundled

together

with nylon

tie wraps, and then securely tied internally

to

the end turns

on

the exciter stator. All

output

load leads

are

marked

per

NEMA

Standard

MG-

I Chapter 2, fitted with crimp type terminal lugs,

brought

out

to

the

connection box and secured

to

the terminal strip located

in

the connection box. Figure 1

on

page

3

illustrates the inter-connections

of

the

two

stator

windings.

For

purposes

of

simplification, only

the

interconnections

of

one phase is shown

on

the

diagram

..

The three phase exciter rotor, acting as the secondary

of

an

integral rotating current

transformer/frequency converter, will have a current induced into it in proportion

to

the

sum

of

the

2

currents

in

both windings

of

the exciter stator. This three phase

AC

current

is

then rectified

to

DC

excitation current

by

a three phase

full

wave rotating rectifier assembly, and fed directly to the main

revolving field via two lead wires secured to the shaft with nylon tie wraps. Residual magnetism (flux)

for initial voltage buildup

is

provided by small permanent magnets embedded, one per pole, in each

of

the pole cores.

7 SERIES

Tl

...

-

<-~~~~~~~~---~~~~~~~~--1

TO

IOSl<M

TIS TIS 3

Tl7

T~

Tl7T~

STATOR

TZ

2 TB

s

TS

3 SERI

014

sau~

TIB

II

9

T9

SERIES

T6

TIS

EXCITER

STATOR

MAIN

INTER-CONNECTIONS

LEADS BROUGHT OUT

MAIN EXCITER

Tl3

T13

Tl

T4

T14 T14

T2

TS

TIS TIS

T3

T6

T16

TO

T7

T17 T17

T8

TIS

T9

Figure 1 CIRCUIT

DIAGRAM-

LIMA"' MAC REFRIGERATION DUTY ALTERNATOR

(For

clarity, only interconnections

of

one

phase

is

diagramed)

Temperature Rise.

Lima®

MAC Refiigeration Duty alternators are constructed with Class F insulating

materials on the stator windings, and

Class H materials on the rotating windings. These machines are

designed for continuous duty, and are conservatively rated at

80° C temperature rise over a maximum

ambient temperature

of

50° C. This rating

will

meet the continuous duty temperature rise requirements

for

Class F insulation

of

NEMA, CSA, IEC, and

all

popular marine classification societies.

Power Factor.

Lima®

MAC Refrigeration Duty alternators are rated at 80% (0.80) power factor. The

. principal design concept

of

the

Lima®

MAC generator

is

to provide electrical power to operate three

phase induction motor loads having operating power factors

in

the range

of0.8

to 0.92, with voltage

regulation

well

within public utility standards.

3

Receiving

Your

New Lima"'

MAC

Refrigeration

Duty

Alternator.

Product is shipped FOB the

factory. Upon receipt

of

the

generator, it is recommended that it be carefully examined for possible

shipping damage.

The

generator was given

to

the freight carrier in

good

condition, thus

the

carrier is

responsible for the product from the factory dock

to

the destination. Any damage should be noted

on

the

freight

bill before accepting the shipment. Any claims for damage must be promptly filed with the

delivering carrier.

Unpacking

and

Handling. Carefully read all instruction tags shipped with the unit. When lifting, attach

an overhead crane

to

the lifting eyes

on

the generator frame. Insure that the lifting eye bolts are firmly

screwed into the frame prior

to

lifting. Apply lifting forces in a vertical direction.

WARNING

THE

LIFTING

EYES

ON

THE

GENERA

TOR

ARE

DESIGNED

TO

SUPPORT

THE

GENERA

TOR

ONLY.

DO

NOT

LIFT

A

COMPLETE

GENERA

TOR

AND

DRIVER

ASSEMBLY

BY

MEANS

OF

LIFTING

EYES

ON

THE

GENERATOR.

PERSONAL

INJURY

OR

DAMAGE

TO

THE

EQUIPMENT

MAY

RESULT.

Storage. In

the

event that

the

generator is not

to

be installed

on

its prime mover immediately, it is

recommended that

the

unit

be

stored in a clean, dry area which is not subject

to

rapid changes in

temperature and humidity.

In

the event

oflong

term storage, see Maintenance Section

of

this manual

for instructions for testing and drying

(if

necessary) prior

to

assembling

to

prime mover.

If

the unit

has been stored for an extended period

of

time in an area where there is considerable vibration, it is

recommended that the bearing/s be inspected and replaced,

if

necessary, prior

to

placing the unit into

service.

Preparation

for

Use. Although the generator has been carefully inspected and tested in operation

prior to shipment from

the

factory, it is recommended that the unit

be

thoroughly inspected, all bolts

checked for tightness, and insulation

on

lead wires examined for chafing prior to proceeding with

installation. Remove all shipping tapes, bags, blocks and

skid~

which are used to prevent vibration

and rotor movement during shipment.

Generator

Mounting.

Single bearing units are provided with an SAE flywheel housing adaptor

flange and flexible drive discs.

Very close tolerances are maintained in the manufacture

of

the

generator so that the alignment procedure is extremely simple. A drive hub

of

nodular iron is shrunk

on the shaft, and special steel drive discs are bolted

to

the hub.

In

some

cases a hub spacer and/or are

inserted between the drive discs and

the

shaft

to

achieve

proper

"G" dimension. Holes are provided in

the periphery

of

the coupling discs which correspond to tapped holes in

the

prime mover's flywheel.

The outside diameter

of

the drive discs fit in a rabbet in the flywheel so that concentricity is assured.

The

SAE flywheel housing adaptor ring and the engine flywheel housing are designed

to

match each

other, with no further alignment necessary. The generator feet have been milled parallel

to

the

axis

of

rotation, however,

the

set sub-base, usually being a weldment, may contain some degree

of

warp.

For this reason, the feet should

be

shimmed where necessary

to

obtain solid contact with

the

sub-base.

4

Torsional Vibration. Torsional vibration

will

be generated

in

all rotating shaft systems to some

degree.

In

some cases, the amplitude

of

these vibrations at critical speeds may cause damage to either

the generator, its driver,

or

both.

It

is

therefore necessary to examine the torsional vibration effect on

the entire rotating system.

It

is the responsibility

of

the generator set assembler to assure the

torsional compatibility

of

the generator and its driver. Marathon

will

supply upon request drawings

showing

all

pertinent shaft dimensions, coup.ling details, rotor weights, locations, and inertias for the

customer to forward to the engine manufacturer for analysis.

WARNING

DISABLE

OR

RENDER

INOPERATIVE

ANY ENGINE

CRANKING

DEVICES

BEFORE

ATTEMPTING

TO

INSTALL

OR

SERVICE

THIS UNIT.

FOR

ELECTRIC

START

SETS,

DISCONNECT

THE

CRANKING

BATTERY.

WARNING

NEVER

"BAR

OVER"

THE

ENGINE-GENERATOR

SET

USING

THE

GENERATOR'S

FAN AS A

FULCRUM.

FAN

MATERIAL

IS

LIGHT

WEIGHT

ALUMINUM

AND

NOT

DESIGNED

FOR

THIS

PURPOSE.

BARRING

OVER

THE

SET

WITH

THE

FAN

COULD

DAMAGE

THE

FAN AND

RESULT

IN

INJURY

TO

PERSONNEL

OR

DAMAGE

TO

THE

EQUIPMENT.

Grade 8 place bolts and hardened washers are recommended to mount the drive discs to the flywheel.

DO

NOT

USE

SPLIT

TYPE

LOCK

WASHERS. Split lock washers when biting into the drive

discs

will

cause stress risers, and may result

in

the discs fracturing.

End play

Test

Procedure. After the generator has been assembled to the prime mover, check for

endplay.

Using a suitabl.e lever, force the engine flywheel forward so that the crankshaft

is

pressed

against its thrust bearing. When force

is

released, the engine crankshaft should remain

in

this

position. Apply force

in

the opposite direction and observe if the crankshaft again remains stationary.

Refer to the engine manual for proper

or

recommended end

play.

If

the crankshaft springs away from

either thrust bearing,

it

is

an indication that the generator shaft

is

not moving freely

in

the assembly,

and normal life

of

the thrust bearing could be impaired. Probable causes

ohhis

problem are:

l. Improper

"G" dimension

on

either the engine or generator. The generator bearing may be

bottoming out

in

the bearing bracket.

2.

Improper seating

of

drive discs

in

the flywheel resulting

in

shaft misalignment.

3. Improper mating

of

generator frame to engine flywheel housing resulting

in

misalignment.

CAUTION

DO

NOT

APPLY

FORCE

TO

THE

GENERATOR

FAN

TO

CONDUCT

AN

END

PLAY

TEST. FAN

MATERIAL

IS

LIGHT

WEIGHT

ALUMINUM AND

NOT

DESIGNED

FOR

THIS

PURPOSE.

APPLYING

SUFFICIENT

FORCE

TO

THE

FAN

TO

MOVE

THE

ENTIRE

SET

ROTATING

ASSEMBLY

COULD DAMAGE

THE

FAN, AND

RESULT

IN

INJURY

TO

PERSONNEL

5

Electrical Connections. The generator conduit box

has

a cable entry hole drilled on the side

of

the

connection box. To minimize the transmission

of

vibration,

it

is

essential that flexible cable

or

cc;:mduit

be used for

all

electrical entrance to the generator connection box. Refer to the connection

diagram supplied with the unit and/or the proper diagrams shown

in

this manual. Install

all

inter-component and external wiring

in

accordance with national and local electrical codes. Insure

that grounding (earthing)

of

the generator frame

and

other components and electrical systems is in

accordance with

all

applicable national and local codes and standards.

The neutral

(LO)

in

a Wye connection may be either grounded (earthed)

or

unground (floating). See

national,

or

local codes and standards, and/or the system distribution wiring schematic diagram for

the proper connection

of

LO.

Figure 2 illustrates the terminal strip mounted

in

the connection box.

Figure

2.

TERMINAL

STRIP

ASSEMBLY

FRAME 260 Lima"'

MAC

ALTERNATORS.

Generator

Load

Lead~

Terminal

Strip

-Mounting Plate

0

Ground

Stud

+-Assembly

Lead

Marker

Note: Neutral lead

TO

is

connected

at

the

factory to

the

frame

grounding

stud

with a

jumper

wire.

If

the

neutral

is

to

be

left

above

ground

(floating),

or

to be

grounded

at

some

other

point,

remove this

jumper

wire

from

both

the

grounding

stnd

and

terminal

TO.

Connection Diagrams. The following two Connection Diagrams are to be used to connect the

generator

in

a Low Voltage (Parallel Wye) 240Y/139 volts connection,

or

a High Voltage (Series

Wye)

480Y/277 volts connection. Jumpering

of

the various generator leads indicated on the diagrams

should be made on the terminal strip. Connection

of

external leads (cables) should also be made

using the mounting screws on the terminal strip.

6

CONNECTION

DIAGRAMS

10

Lead

Low (Parallel) Wye: 240Y/139 Volts

10

Lead

Hi

(Series) Wye: 480Y/277 Volts

7

L-l

4so'v

Connections to be

made

on terminal

strip.

Ll

=Tl

& T7

Jumpered.

L2

= T2 & T8

Jumpered.

L3 = T3 & T9

Jumpered.

LO=

T4, TS, T6,

TO

Jumpered.

Connections to

be

made

on

terminal strip.

Ll=Tl

L2=T2

L3=T3

LO=TO

Series Connections

Jumper

together

T4

&

T7

Jumper

together TS &

T8

Jumper

together

T6

& T9

Fault

Current

Sustaining. A close inspection

of

Figure 1 will show that the

Lima®

MAC generator

derives its excitation from load current. Thus, these units will support in the order

of

500%

of

rated

current in fault current during fault conditions assuring fault clearance without the addition

of

any

form

of

excitation support system.

In

a sense, the exciter is a total current boost system.

OPERATION

Pre-Start

Inspection. Before starting the unit for the first time, the following inspection and checks

are recommended:

1.

A visual inspection should be made for any loose parts, connections,

or

foreign materials such as

cut offtiewrap ends, scrap insulating tape, tools,

hardware, etc

..

2. Check for clearance in the generator and exciter air gap. Insure that the set turns freely.

Bar

the

set over by hand for at least 2 revolutions

to

be

sure that there is no interference.

WARNING

NEVER

"BAR

OVER"

THE

ENGINE-GENERATOR

SET

USING

THE

GENERATOR'S

FAN

AS A FULCRUM.

FAN

MATERIAL

IS

LIGHT

WEIGHT

ALUMINUM

AND

NOT

DESIGNED

FOR

TIDS

PURPOSE.

BARRING

OVER

THE

SET

WITH

THE

FAN

COULD

DAMAGE

THE

FAN AND

RESULT

IN

INJURY

TO

PERSONNEL

OR

DAMAGE

TO

THE

EQUIPMENT.

3. Check all wiring against the proper connection diagrams, and insure that all connections

on

the

terminal strip are securely tightened.

4.

Insure that

all

equipment is properly grounded (earthed).

5.

Inspect for any remaining packing materials and remove any loose debris, rags, etc., that could

be drawn into the generator.

6. Check

all

fasteners for tightness.

7.

Check

all

covers, screens and guards.

If

they have been removed for assembly

or

inspection,

reinstall and check for security.

8. Review

all engine pre-start instructions, and insure that

all

recommended steps and procedures

have been adhered to.

Starting-up

the

Generator

Set. The following procedure should be followed for starting-up the

generator set for the first time.

1.

The generator output must be disconnected from the load.

Be

sure that the

main

circuit breaker

on

the open position.

8

-------·-------------

-----

2.

Insure that all engine pre-start and start-up procedures have been followed.

3.

Start the engine and adjust it for proper speed. For 60 Hertz operation, synchronous speed is

1800 RPM.

4.

Check all Line

to

Line and Line

to

Neutral voltages for balanced voltage.

If

voltages are

unbalanced, shut down the equipment and check for improper wiring. Correct any mistakes, restart

the set and again check for voltage balance.

If

the problem persists, consult the factory.

6. Close the main circuit breaker

to

the load.

7.

Monitor the generator output current

to

verify it is

at

or

below nameplate value.

8.

Check generator speed under load. Adjust as necessary. (Refer

to

engine/governor manuals)

Shut

Down

Procedures

There are no specific instructions for shut down

of

the generator, but several good engineering

practices should

be

observed

to

prolong equipment

life.

I. It

is

advisable

to

disconnect all loads (open main circuit breaker) prior

to

shut down.

2. Isolate any condition that could allow the generator

to

see a voltage

at

its terminals while

at

rest.

Failure

to

do this could result in personnel injury or equipment damage.

MAINTENANCE

Routine

Maintenance.

Your

Lima®

MAC generator has been designed

to

be as reliable and trouble

free as is possible. However, costly

repairs and down time can

be

minimized by operating the unit

under conditions that are compatible with those at which the equipment was designed

to

operate. (See

Operation Section) The following maintenance procedures should

be

followed

to

insure long

equipment life and satisfactory performance:

1.

Routinely check intake and exhaust air screens

to

insure that they are clean and free

of

debris.

Clogged intake air screens will reduce cooling

air flow, and may result in the unit operating

at

dangerously high temperatures, and reduce the generator's life. This inspection and cleaning should

be

done in conjunction with prime mover air filter cleaning and/or change out.

2. Periodically (approximately every thousand operating hours) check the bearing.

Your

generator

is equipped with a pre- lubricated for life bearing which does not require routine lubrication. Bearing

check may

be

done by listening

to

the bearing during operation with a stethoscope. An alternative

method is

to

apply the blade

oflong

shanked screw driver

to

the

bearing carrier adjacent

to

the

bearing. Keeping well clear

of

any rotating elements, place your

ear

to

the handle and listen for

excessive bearing noise.

If

undue noise exists; shut the unit down, inspect the bearing and replace it,

if

necessary, following instructions in the service section

of

this manual.

9

3. Periodically inspect the unit for buildup

of

contamination (dirt, oil, etc.) on the windings. Clean

as necessary following instructions in the Service Section

of

this manual.

SERVICE

Drying

Generator

Windings. Generators that have been in transit

or

storage for long periods

of

time may be subjected

to

extreme temperature and moisture changes. This can cause excessive

condensation, and the generator windings should be thoroughly dried .Jut before operating the unit.

If

this precaution is

not

taken, serious damage

to

the generator can result.

CAUTION:

DO

NOT

RUN

THE

GENERATOR

AT

RATED

SPEED

WITH

WET

OR

VERY

MOIST

WINDINGS.

THE

EXCITATION

SYSTEM

IS

SUCH

AS

TO

CAUSE

VOLTAGE

TO

BE

PRESENT

\VHENEVER

THE

UNIT'S

SHAFT

IS

ROTATING

ABOVE

1200

RPM.

The following procedures should be taken to effectively dry the unit's windings:

Oven. Place the machine in an oven and bake it at a temperature not

to

exceed 194° F (90° C).

Hot

air.

Run

the engine at a low idle speed, not

to

exceed 1000 RPM, and blow hot air from a space

heater

or

other appropriate device into the generator's intake air openings. Suggest this be done for at

least one hour.

To

prevent harmful voltages being generated in the stator windings during the dry-out

period, it is necessary

to

keep shaft speed below the generator's voltage build-up speed.

For

this

procedure, bring the engine speed as slowly as possible up to 1000 RPM, Do

not

let

the

engine

speed exceed 1000

RPM

during

start-op

or

during

the

drying

process.

Cleaning

Methods.

When electrical components get dirty, the insulation must be cleaned. There are a number

of

acceptable methods for cleaning the generator, each

of

which will necessitate disassembly

of

the unit.

The method

of

cleaning will be determined by

the

kind

of

dirt,

and when the unit must be placed into

service. Drying after cleaning

is

necessary. An authorized Marathon Service Center,

or

an electric

motor repair shop in your area can normally assist with the proper cleaning

of

the generator

windings. They will usually be experienced in problems areas such as road salt, dust,

dirt, engine oil,

and

coastal marine environments.

Whenever the generator is disassembled, the windings should be given a thorough inspection, and the

insulation cleaned,

if

necessary. The inspection should include the connection

of

the

windings,

insulation, and varnish coverage. Check the winding ties and coil supports.

Look

for any sign

of

coil

movement

or

looseness, and repair as required.

Solvents. A solvent is usually required

to

remove accumulated soil containing oil

or

grease. Only

petroleum distillates should be used for cleaning electrical components. Petroleum solvents

of

the

safety type with a flash point

of

greater than 100° F (38° C) are recommended.

10

CAUTION:

WINDING

VARNISHES

ARE

EPOXY

OR

POLYESTER

BASED

MATERIALS.

A

SOLVENT

THAT

DOES

NOT

ATIACK

THESE

MATERIALS

SHOULD

BE

USED.

Apply

the

solvent with a soft brush

or

rag.

Be

careful not to damage the magnet wire

or

insulation

on

the windings. Dry components thoroughly with moisture-free, low pressure compressed air.

WARNING

ADEQUATE

VENTILATION

MUST

BE

AVAILABLE

TO

A

VOID

FIRE,

EXPLOSION,

AND

HEALTH

HAZARDS

WHERE

SOLVENTS

ARE

BEING

USED.

AVOID

BREATHING

SOLVENT

VAPORS.

RUBBER

GLOVES

AND APRONS,

OR

OTHER

SUITABLE

HAND

AND

BODY

PROTECTION

SHOULD

BE

USED ..

WEAR

EYE

PROTECTION.

Cloth

and

Compressed

Air.

Cleaning with a dry cloth may be satisfactory when components are

small, the surfaces are accessible, and only

dry dirt

is

to be removed. Blowing dirt

out

with

compressed air is usually effective particularly when the dirt

bas

collected in places that cannot be

reached with a cloth.

Use clean dry air

at

30

PSI

(206 KP A).

Brushing

and

Vacuum Cleaning.

Dry

dust and dirt

may

be removed by brushing with bristle

brushes followed by vacuum cleaning.

Do

not use wire brushes. Vacuum cleaning is an effective and

desirable method

of

removing dry and loose dirt.

Steam

Cleaning.

If

the generator is completely disassembled, including bearings and rotating

rectifier assembly, steam cleaning

of

major parts and windings

is

very effective. However,

the

machine must be thoroughly dried in an oven

to

remove all moisture before the unit

can

be

put back

into service.

Restoring

Residual Magnetism. The current necessary to magnetize the alternator field during

operation

is

obtained from the exciter. Initially, upon starting the unit, voltage is induced into the

main

stator (armature) by the flux across the air gap supplied by the permanent magnets embedded in

the poles

of

the main rotor. Current then flows through interconnecting leads

to

the shunt portion

of

the

exciter stator which induces current in the exciter rotor. This current is then rectified

to

DC

excitation current by the rotating rectifier, and fed to the

main

field windings via

the

main

rotor leads

further strengthening the main field until rated voltage

is

reached.

The residual magnetism contained in

the

field poles

of

the

main

rotor

may be lost

of

severely

weakened by a strong neutralizing magnetic field from any source,

or

if

the unit has

not

operated for

a long period

of

time. Should

the

generator

.fail

to build up voltage after being disassembled for any

reason, a momentary short circuit

of

any

two

generator output leads should be sufficient

to

correct

this condition.

If

not, an alternate method may be used. Apply either an alternating

or

direct current

voltage

of

from 20 to 30 volts

to

any

two

generator output leads.

Do

not make a

firm

connection, but

rather tough the leads together until

the

generator voltage begins

to

rise and then remove.

It

is

suggested that a

30 ampere· fuse be inserted in the supply voltage circuit

to

prevent any damage in

case the build-up power supply voltage is not removed quickly enough.

Both

of

these procedures

must be conducted while the generator is running at rated

1800

RPM

or

slightly higher speed.

11

--------------··

--------

Reversing

the

Phase

Sequence

of

a

Rewound

Stator. There have been many instances

where

a

repair facility will rewind either a main stator

or

an exciter stator

on

a MAC generator, and

then

not

be

able

to

generate a voltage

at

the terminals during test running. In almost every case

of

this nature,

the problem

is

in

the

phase sequence

of

the rewound stator.

A briefreview

of

the Principals

of

Operation

will

show that both the main stator and the exciter

stator are interconnected, and that current is generated in the main stator, flows through

the

exciter

stator and

out

to

the load. Since both the main rotor and the exciter rotor are

on

the same shaft, and

turning in the same direction,

the

phase

Sffiuence

ofthe

exciter

stator

must

be

opposite

to

that

of

the

main

stator

or

the

unit

will

not

build

up

voltage.

To

correct this problem, you will have

to

reverse the phase sequence

of

the rewound stator.

To

reverse the phase sequence, all lead tags

of

one phase

of

the exciter stator will

be

swapped

with

the leads

of

another phase, and then these renumbered leads will

be

connected

to

matching numbered

leads

of

the main stator as shown below under "Trial Connections".

If

the generator functions

nonnally after swapping leads, re-number

the

leads that were swapped. Re-numbered leads should

then be preminantly connected as shown in Figure I, page 3.

SWAP LEADS

TRIAL

CONNECTIONS

-

Hi

WYE

EXCITER

MAIN

EXCITER

EXTERNAL

TS

&

T6

T13

-

T13

Tl-LINE

T8

&

T9 T14

-

TIS

TI-LINE

TI4

&

TIS

-

T14

TI-LINE

T17 &

TIS

T16

-

T16

T4-T7

T17

-

TIS

TS-TS

TIS

-

T17

T6-T9

TO

Bearing

and

Exciter

Rotor

Removal

and

Replacement

Procedure.

Prior

to

commencing this

operation, it is suggested

that

the alternator's shaft be rotated until two

of

the main

rotor

poles

are

in a

vertical position. Once

the

bearing bracket is backed out, the rotor will drop

on

the main stator core.

Having the rotor in this position

will limit the amount

ofrotor

drop

to

that

of

the

air gap. ·

A.

Bearing

Bracket

Removal

Procedure.

In

order

to

remove the bearing canier, you

must

first

remove the two side vent drip covers and louvered panels. (See Parts List Items I and 2).

Remove the four 5/16 -18 rear bearing bracket hex head cap screws

to

release the bracket. Using a

fiat

blade screw driver

or

chisel, pry the bracket back from the frame. After approx. 1/8 inch the

bracket will clear the locating register

on

the

frame, and the bracket will drop until the

rotor

is resting

on

the main stator core. Continue

to

pull

the

bracket free from

the

bearing. Visually inspect

the

bearing bore for damage

or

wear.

If

worn

or

damaged, replace prior

to

reassembly.

12

NOTE:

There is an

"0"

ring installed in the bearing bore

of

the bearing bracket. Inspect this 0 ring

for wear

or

damage, and replace

if

necessary.

B.

Bearing

Removal

Procedure.

Visually inspect the bearing for obvious wear

or

damage

before removing.

Using a bearing puller, remove

the

bearing.

If

possible, insure that

the

puller is

against the inner race

of

the bearing

to

prevent damaging the bearing.

C.

Bearing

Replacement.

ALWAYS

install the same type and size bearing that was supplied

as original equipment. Order by part number from the parts list, and include the unit serial number

and

part number when ordering. Heat the bearing

to

a maximum

of

212°F in an oven. Apply a thin

coat

of

clean lubricating oil

to

the press-fit area

of

the rotor shaft. Using suitable heat resistant

gloves, install the bearing over the end

of

the shaft until it seats against the shaft shoulder. The

bearing should slide

on

the shaft and

be

seated without excessive force. Should the bearing bind

on

the shaft prior

to

being seated against the shoulder, a piece

of

tubing slightly larger than

the

press-fit

area can

be

used

to

drive the bearing home. Using light taps with a soft mallet, apply pressure

to

the

inner race only.

Testing Diodes

on

the

260

Frame

Rotating

Rectifier

Assembly. Following the procedures in

Paragraph A above, remove the

bearing carrier. The rotating rectifier assembly is in-board

of

the

bearing and is mounted

on

the exciter rotor core. Refer

to

Figure 4 for reference

to

diode polarity and

part identification.

Figure 4.

STUD

TYPE

DIODES

Forward

(Normal)

Reverse {

R)

Anode -

Terminal

Q

__/

End

."'----

13

~~

Stud

End

........ _

....

'"'

......

t-'

...............

&4...,...,'"'1.uu.ly

....

vu•u::>l.<:>

ui.

t.wu

~t:1ru-c1rcu1ar

suo-assemoues

~ee

.t·1gure

5.

The half

assembly having white leads

on

the diodes contains three "Forward" stud type diodes, and the

half

assembly having black leads on the diodes contains three "Reverse" stud type diodes.

The diodes may

be

tested in the field without removing them from the heat sinks. Electrically isolate

the individual diodes by removing each

of

exciter

rotor

lead flag terminals from the quick c01:nect

diode terniinals, and remove the

two

main

rotor

leads from the main rotor terniinal posts. Test each

sub-assembly separately.

An ohmmeter

or

a battery light continuity tester may

be

used

to

finci

an

open

or

shorted condition in the diode. Place one tester probe on the main post.

In

successio::. touch

the other test probe

to

each diode terminal. Reverse the probes and repeat

the

procedure. Y m have

now tested the three diodes

on

this sub-assembly. Repeat the test on the second sub-assembiy.

These tests should indicate one

ofthree

conditions:

(1) Good diode:

Will

have a much greater resistance in one direction than the other. Typical

reverse resistance will be

30,000 - 300,000 ohms

or

greater, while typical forward resistance will

be

less than

10

ohms. The battery-light tester will have the light "on" in one direction, and "off" in the

other.

(2) Shorted condition: Ohmmeter reading will

be

zero,

or

very low in both directions. The

continuity tester will have the light

"on" in both directions.

(3)

Open condition: Ohmmeter will have a maximum (infinity) reading in both directions.

Continuity tester light will be dark

(off) in both directions.

Figure 5. ROTATING RECTIFIER ASSEMBLY

MAIN

ROTOR

LEAD

WHITE

LEADS

FROM

EX.

RTR.

TO

CONNECT

TO

RECTIFIER

ASSY.

WITH

WHITE

LEADS

I

//i~TI--l\-_;

1

t+-_MAIN

ROTOR

LEAD

J

/

MOUNTING

SCREW

TORQUE

TO

40-50

IN.LBS.

BLACK

LEADS

FROM

EX.

RTR.

TO

CONNECT

TO

RECTIFIER

A5SY.

WITH

BLACK

LEADS

-----=

--

BLACK

POST

14

Diode failure after approximately a 25

hour

"run-in" period is generally traceable

to

external

causes

such as lightning strike,

over

heating, reverse current fed into

the

unit, line voltage spikes,

etc

..

All

6

diodes are essentially in

the

same

circuit. When one

or

more diodes have been stressed

to

fuilure,

there

is no easy method

to

determine

how

badly stressed

the

remaining diodes may have been.

Therefore,

to

avoid possible continued failures and increased

down

time, it is recommended

practice

to

replace

the

entire assembly

rather

than

to

replace only

the

individual failed diodes.

If

the

rectifier

assembly is

to

be

repaired,

the

assembly must

be

removed from

the

unit.

Rotating

Rectifier

Assembly

Removal

and

Installation

Procedure.

As illustrated in

Figure

5,

the

rotating rectifier assembly consists

of

two

semi-circular sub-assemblies.

To

remove each

sub-

assembly, remove

the

three

exciter

rotor

lead flag terminals from

the

quick connect tenninals,

and

remove the

main

rotor

lead

from

the

main

rotor

tenninal post.

Remove

the

two

retaining

screws

from

each mounting board. After repair,

or

if

the

assemblies are

to

be

replaced, install each sub-assembly

in

the

same place

as

before.

Pay

particular attention

to

assure

that

the

white exciter

rotor

leads

are

installed on

the

sub-assembly having white diode leads, and

that

the

assembly having black

diode

leads receive

the

black exciter

rotor

leads.

Replacing

Diodes

on

the

Rectifier

Assembly. Prior

to

installing a replacement diode

on

the

heat

sink, sparingly apply a film

of

conductive heat sink compound around

the

base

of

the

diode

(do

not

coat

the

threads).

When

installing a diode

on

the

heat sink, care should

be

taken

not

to

over

torque

the

retaining nut

which

could

cause

damage

to

the

device.

Torque

to

28

to

30

pound-inches.

If

not

damaged,

the

existing

diode

lead

wire may

be

unsoldered from

the

failed diode, and resoldered

on

the

replacement.

RETURNED GOODS

Contact

Marathon

Electric

Manufacturing

Corporation

by telephone, fax,

or

letter

for

a

"Returned Material Authorization" (RMA) number before returning

component

parts

or

complete

units.

We

will

take

steps

to

return

your

unit

to

service quickly and

at

the

least expense possible.

At

the

same time,

we

will

analyze

the

cause

of

failure and, in

so

far as is possible, recommend steps

to

be

taken

to

prevent a recurrence

of

the

problem.

CAUTION

-

Single

bearing

generators

must

have

their

rotor

assembly

properly

secured

to

prevent

damage

during

transit

to

the

factory,

or

to

an

authorized

service

center.

15

----------

-------

TROUBLESHOOTING PROCEDURES

This section is intended

to

suggest a systematic approach to locating and correcting generator

malfunctions. The section is arranged according to the symptoms

of

the problem. The steps have

been arranged in an attempt to,

1,

do the easy checks first,

2.

prevent further damage when

troubleshooting a disabled machine.

The first and perhaps most important step

of

troubleshooting should to be to gather as much first

hand information as

is

possible from operating personnel

or

people who may have been present at the

onset

of

the trouble

or

failure. Information as to how long the unit had been operating, what loads

were on line, weather conditions, which,

if

any, protective equipment

or

devices functioned,

or

failed

to function, etc. can help

to

isolate the problem.

Always make a thorough visual inspection to check for any obvious problems before attempting

to

run the generator.

WARNING

HIGH

VOLTAGES

MAY

BE

PRESENT

AT

THE

GENERATOR

TERMINALS

WHEN

THE

UNIT IS

RUNNING

.•

TOOLS,

EQUIPMENT

CLOTHING

AND

YOUR

BODY

MUST

BE

KEPT

CLEAR

OF

ROTATING

PARTS

AND

ELECTRICAL

CONNECTIONS.

EXTRA

PRE-CAUTIONS

MUST

BE

TAKEN

DURING

TROUBLESHOOTING

SINCE

PROTECTIVE

COVERS

AND

SAFETY

DEVICES

MAY

BE

REMOVED

OR

DISABLED

TO

GAIN

ACCESS

AND

MAKE

TESTS.

BE

CAREFUL.

SERIOUS

PERSONAL

INJURY

OR

DEATH

CAN

RESULT

FROM

THESE

HAZARDS.

CONSULT

QUALIFIED

PERSONNEL

WITH

ANY

QUESTIONS.

Speed Deviations: The generator speed should be maintained at rated nameplate value during all

operating tests.

The

frequency and voltage

of

the generator output depends upon rotative speed.

If

the

generator runs slower than rated speed, voltage and frequency will drop

off

proportionately.

SYMPTOM:

GENERATOR

PRODUCES

NO

VOLTAGE,

OR

RESIDUAL

VOLTAGE

CAUSE

Low Speed.

Voltmeter Off.

Defective voltmeter.

Loss ofresidual

Open in stator windings.

service

CHECK

AND

REMEDY

Check driver RPM. Correct as necessary.

Check meter selector switch to insure it i not in the

Off

position.

Check voltage with separate meter

at

the generator terminals.

Flash the field. See "Restoring magnetism. Residual Magnetism"

Check for continuity in the windings. Return

to

factory,

or

take

to

shop

if

open.

16

Defective diodes.

Broken

or

shorted

exciter

or

main

rotor leads.

Defective exciter

Improper phase rotation

in rewound exciter

stator

or

main stator.

Check rectifier assy. Repair

or

replace as necessary.

Test and repair or replace.

Inspect for damaged

or

burned

or

main

rotor

or

main

rotor

windings.

Check resistance with Kelvin bridge. Megger for short

to

core. Return

to

factory

or

take to service shop to effect repairs.

Reverse

tag

rewound component.

SYMPTOM:

GENERATOR

PRODUCES

LOW

VOLTAGE,

NO

LOAD

CAUSE

CHECK

AND

REMEDY

Faulty metering.

Check voltage with separate meter at generator terminals.

Low

Speed

Check driver for proper speed. Adjust as necessary.

High resistance connections. Check

all

tenninations. Re-make as necessary.

Faulty diodes. Check rectifier assy.

Faulty main rotor. Check main rotor pole windings.

If

winding appears to bulge mid-way

down body

of

pole, refer to service shop,

or

return

to

factory for

sefV!ce.

SYMPTOM:

GENERATOR

PRODUCES

LOW

VOLTAGE

WHEN

LOAD

APPLIED

CAUSE

Driver speed droop.

Excessive load.

CHECK

AND

REMEDY

Check engine.

For

proper operation, engine must be running

approximately

1800 RPM. Adjust governor as necessary.

Reduce load. With 3 phase units, the load

on

each leg should be as

balanced as possible, and should not exceed rated current

on

any leg.

SYMPTOM:

GENERATOR

PRODUCES

FLUCTUATING

VOLTAGE

(May be indicated by light flicker)

CAUSE

Irregular engine speed.

Loosetenninallugs

or

screws.

CHECK

AND

REMEDY

Check engine for malfunction,

or

load for fluctuation.

Make

better connection both mechanically and electrically.

17

causing uneven air gap.

Replace as necessary.

SYMPTOM: GENERATOR PRODUCES IDGH VOLTAGE

CAUSE

CHECK

AND REMEDY

Faulty metering.

Check voltage with separate meter at generator tenninals.

Excessive speed. Check engine for malfunction,

or

improper governor setting.

SYMPTOM: GENERATOR IS OVERHEATING

CAUSE

Generator

is

overloaded.

rating.

Clogged ventilating

screens.

High room temperature,

or

altitude.

Insufficient circulation

of

cooling air.

Unbalanced load.

Dry

bearing.

CHECK

AND REMEDY

Reduce load. Check with ammeter and compare with nameplate

Clean air passages.

Improve ventilation, or reduce load.

Provide cross-ventilation.

The load

on

each leg should be as evenly balanced as possible, and

should not exceed rated current on any leg.

Replace bearing.

SYMPTOM: GENERA

TOR

PRODUCES MECHANICAL NOISE

CAUSE

Defective bearing.

Loose screens

or

guards.

CHECK

AND REMEDY

Replace bearing.

Check screen band, intake

air

screens and louver assembly for

tigntness. Tighten as necessary.

SYMPTOM: GENERATOR PRODUCES SHOCK WHEN TOUCHED

CAUSE

Static charge.

Grounded armature

or

field coil.

CHECK

AND REMEDY

Ground generator frame.

Return

to

factory for repair.

18

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Marathon SB516 Owner's manual

Marathon SB516 Owner's manual

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