Karsten Moholt AS
Servicing industry throughout
Norway and the world since our
1945 incorporation
All Areas of Maintenance
Offshore
Industrial
Hydro
Traction
Shipping
Service Area
Available Services
• Full service repair
shop for rotating
electrical equipment
and other electrical
equipment
• Field services
• Condition monitoring
• Engineering and
technical services
• Product sales
Personnel
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More than 160 employees
Electrical engineers
Condition monitoring engineers
Motor rewinders
Mechanics
Electricians
Service electronics
Service specialists
Certified welder
Paint and sandblast personnel
Qualifications/Certification
• ISO 9001-2000 Quality assurance program
• ISO 14001:2004 Environment assurance
program
• IECEx sertified service facility :IEC 60079-19
• UL sertified service facility
• Achilles certified
• Nemko certified workshop for repair of Exequipment
• EASA: Electrical Apparatus Service
Association
IECEx
• Karsten Moholt AS is
Scandinavia's first and only
IECEx certified service facility
• Nemko is national scheme in
Norway
• IECEx is an international
scheme
• The IECEx scheme allows
Karsten Moholt AS to repair
according to existing norms
– Karsten Moholt AS do not
need factory documentation
for Ex equipment, to be able to
repair
Full Service Repair Shop
• Ex certified
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Motor service
Motor rewind
Transformer service
Transformer rewind
Heater service
Heat exchanger service
Mechanic workshop
Balancing
Testing and analysis
Rewind workshop
• Explosion proof up
to 13,8 kV
• Generators and
motors
– Stator rewind
– Armature rewind
• Transformer
rewind
Core loss testing
• Core loss testing
– Before and after testing of the stator core
confirms the integrity, therefore guarantees
performance and efficiency
Burn off facilities
• Precision-controlled burn-off ovens, allows
the precision controlled removal of the
previously installed stator winding
Burnout ovens with capacity up to
2,2mx2,2mx3m
Mechanical workshop
• 5 lathes with capacity up to
diameter 1,6 meter and weight
6 tons
• Vertical turning with capacity
up to diameter 2.1 meter and
weight 6 ton
• Hydraulic press (200 tons)
• Milling machines
• Electrical saw for metals with
diameter up to 450 mm
• Welding equipment AC and
DC
• Plasma burner
• Metal spraying equipment
Balancing
• Dynamic balancing stand to 12000 kg
• Unlimited field balancing capability
Vacuum pressure treatment
• Best penetration
• Tixotropic Varnish
• Minimum run-off
while curing
• Capacity for large
machines
– Diameter: 2.5 m
– Heigh:3.6 m
– Weight: 20
Tonnes
Transformer Repair
• Overhaul oil filled & dry
type transformers
• Testing
• Repair
• Rewinding
• Site repair
Heater repair shop
• Repair and service of
industrial and Ex
heaters
• Replacement of
elements
• Pressure test
• Resertification
Heat exchange repair shop
• Repair and overhaul
of all types of heat
exchangers
• Pressuretesting
• Certification
Welding Repair Shop
• Complete overhauls
and minor tune-ups
• Jobsite servicing
• Factory-trained
personnel
• OEM replacement
parts
Pump repair shop
• Pump motors and pumps:
• Repair and overhaul of all
types of pumps
– Industrial
– Ship
– Offshore
• Submersible pump motor repair,
overhaul and rewind
Separate test facility for pumps
with verification of characteristics
Surface treatment facility
• Specialised Norsok M501
workshop for
– Motors and generators
– Sandblasting
– Metallization
– Painting
Electronic workshop
• Repair of electronic units:
– Printed circuit boards
– Power supplies
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Radar equipment
Monitors
Regulators
Welding equipment
Forklift workshop
• Diesel and electric forklifts, side
loaders, cleaning machines and high
pressure washing equipment.
• Specialist in EX forklifts. Repair and
service at the customers premises or
in our workshop
Electrical and Mechanical
Capacity
• Electrical testing capacity
– 500 kVA, 6000V AC
– 700 Amp (440 V)
– 1000 V DC
• Mechanical:
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30 ton hoist
6 ton forklift
12 ton balancing stand
12 ton lathe machine
Test Facilities
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Test-driving facility with following
specification
– Diesel aggregate 500kVA 20 – 60 Hz.
– AC and DC load testing facility up to
1200kW
– Test equipment for documentation of
motor losses, efficiency temperature
and other parameters in repaired and
overhauled equipment. Steples
control of test voltage between 0 –
6000V
– High voltage testing offline for tan δ,
partial discharge and Polarisation
index test
– High-frequency Interturn Short
Tester 0-12 kV
– Equipment for detection of damaged
rotorbars and endrings
Field Services
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Generator repair
Motor repair
Change of bearing
Balancing
Aligment
Rewinding
Machining
Transformer repair
Motor installation
Dry ice blasting
High voltage testing
Vibration measurement
Thermography
Generator Repair
• Turbine generator
– Overhaul
– Rewind
– Re-wedge
– Re-laminate
– Upgrade
Hydro Power Repair
• Hydro generator
– Overhaul
– Rewind
– Re-wedge
– Re-laminate
– Upgrade
Motor Installation
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Motor removal and re-installation
Change of bearings
Vibration analysis
Laser alignment
Dry Ice Blasting
• Clean sensitive electronics in electrical
panels
• Stator windings
• Transformer bushings
Engineering and Technical
Services
• Total maintenance
planning
• Partial discharge
measurement and
analysis
• Diagnostic center
• Training
• Transformer oil analysis
• Engineering services
• Power system
Engineering
Vibration analysis
• Vibration measurements /
acceptance testing
• Vibration analysis /
diagnostic
• Temp. installation of online
systems
• Diagnostic center for remote
diagnostic which analyze all
measurements witch is sent
to us by E-mail. Both for
online and offline systems.
Partial Discharge Analysis
• Partial discharge
measurement
• Sensor installation
• Analysis of results
Transformer Oil Analysis
• Transformer oil sampling and analysis
– Dissolved gas content
– Oil quality analysis
Power System Engineering
• Transient analysis
– Stability studies
– Switching analysis
• Power quality analysis
– Harmonic analysis
– Filter design
– Power factor correction
• Testing and repair of breakers
• AVR projecting and installation
Product Sales
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New motors/generators
AVR
Ball Bearings
Drives and starters
Vibration measurement systems
Forklifts
New Motors/Generators
• Brands:
– Abb
– Leroy Somer
– Siemens
– Alconza
• Industrial and Explotion proof
• Big stock of Abb Ex motors
• NOK 6M in inventory
Drives and Starters
• Drives
– Abb
– Leroy somer
Ball Bearings
• Schaffler/FAG
• One of the largest
stock in Norway of
ball-bearings
– Several thousand
different types in stock
Historie
 Nødgenerator på Oseberg-C
 Fabrikat: Siemens
 Installert i 1990
 Tørt miljø
 Testkjørt hver 14 dag.
Er ellers ikke i drift med mindre en
nødssituasjon oppstår
Survey av generator/tilstandskontroll på
plattform
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Startet med visuell inspeksjon
av generator av personell på
plattform i forbindelse med
rutinevedlikehold
Det ble avdekket salt i vikling,
og generator ble derfor
besluttet sent til verksted for å
sikre skikkelig rengjøring
Målinger ble utført, men det
ble besluttet at maskin skulle
sendes i land for
forebyggende vedlikehold
Mottakskontroll
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Visuell kontroll
Mekanisk kontroll
 Klaringer for lagre ble målt
 Akseltetninger ble kontrollert
 Tetnningsposisjoner ble
kontrollert
 Aksling ble kontrollert for kast
 Elektrisk kontroll
 Ikke destruktive målinger ble
utført
 Isolasjonstest ble utført
 Tan (d) test ble utført
 PD test ble utført
 PI test
 Surgetest ble utført
Winding Faults
Funn ved tilstandskontroll
 Visuell kontroll
• Strips i generator var blitt porøse. Disse kan løsne og
gjøre skade på generator, og ble derfor anbefalt
benslet inn.
 Mekanisk generator i god stand
• Små justeringer og skifte av slitedeler som ble
anbefalt
 Vikling var i tilfredsstillende stand, men tegn til
forringelse ble oppdaget
• VPI ble anbefalt for å forbedre kvalitet på
viklingsisolasjon og forlenge levetid å vikling.
Reparasjon utført
 Mekanisk reparasjoner utført
 Porøse strips er bendslet inn
 Lagre justert
 Rotoraksling kontrollert for kast
 Tetningsposisjon polert
 Akseltetninger er byttet
 Elektriske utbedring utført
 VPI lakket generator
 Utført nye elektriske målinger
Resultat
PI målinger for og etter VPI
200
180
160
140
120
PI målinger før utbedring
100
PI målinger etter utbedring
80
60
40
20
0
1
2
3
4
5
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7
8
9
10
Resultat forts
PD før og etter VPI
17
15
13
11
PD grenseverdi
9
PD før utbedring
7
PD etter utbedring
5
3
1
-1
1
2
3
Resultat forts
Tan (d) før og etter VPI
4,5
4
3,5
3
Tan (d) grenseverdi
2,5
Tan (d) før utbedring
2
Tan (d) etter utbedring
1,5
1
0,5
0
1
2
3
Konklusjon
 Generator var i god stand i forhold til
alder, men den hadde startet et forløp
av forringelse grunnet høy alder
 Det var små tiltak som skulle
implementeres for å sette tilbake
generator i ”god som ny” tilstand. Dette
var tilfelle fordi generator ble sendt til
verksted for utbedring før den var
kommet langt i forløpet på PF-kurven.
 Dersom forringelse prosess hadde fått
fortsette, ville det blitt mer omfattende
og kostbart og sette generator i stand
igjen.
 Dersom prosessen får gå for langt,
er det kanskje ikke mulig å oppnå
”god som ny” tilstand for
 Generator kom inn akkurat i rett tid.
Turbingenerator
overhaling
Offshore installasjon
Spesial oppdrag
Arbeidsomfang
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Oppgradere ytelse fra 24 MVA til 30 MVA
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Bistod i prosjektering av trekkeverktøy i
samarbeid med Brush
Utarbeidet prosedyre for gjennomføring
overhaling og oppgradering
Utførte hovedoverhaling
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Komplett nytt kjølerhus
Ny oppgradert rotor
Ny exciter
Inspeksjon
Utbedret stator
Overhaling m/rotor skift
Installasjon av ny kjøler
Testing og prøvekjøring i samarbeid med
Brush
Overhaling av gammel exciter på vårt
verksted
Overhaling av gammel kjøler på vårt
verksted
Skisse på planløsning
Skinnegang montert
Ny kjøler sliskes på plass
Ny kjøler monteres
Demontering av exiter
Rotor trukket ut på 2stk.
spesialvogner
Sikring av stator og rotor
• Sikringsplate i bunn av stator samt støtte
sideveis
Ende stopper på uttrekks skinne
Rotor på transportvogn
Klargjøring av løft
Rotor løftet opp med 2stk. 10 tonns
taljer
Taljer slakket av, rotor henger nå i
kran
Rotor i luftig svev (styretau)
Rotor låres ned i transportkasse