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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
MAIN EXCITER
Tl3
T13
Tl
T4
T14 T14
T2
TS
TIS TIS
T3
T6
T16
T16
TO
T7
T17 T17
T8
TIS
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
EXCITER
MAIN
EXCITER
EXTERNAL
TS
&
T6
T13
-
T13
Tl-LINE
T8
&
T9 T14
-
TIS
TI-LINE
TI4
&
TIS
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
/
