GE OTCF User manual

Instruction Manual
© GE Grid Solutions
INSTRUCTION MANUAL NUMBER MI-ITR103
CAPACITOR VOLTAGE TRANS ORMER
MODEL OTC
VOLTAGE LEVEL: 72,5kV TO 800kV

Instruction Manual
© GE Grid Solutions
GE Grid Solutions
Av. Nossa Senhora da Piedade, 1021
37504-358 Itajuba - MG – Brazil
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ITR069
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AIB - 02 14/09/2021 FES TAA
AIB - 01 04/09/2018 TAA FES
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Owner Control Revision Date Prepared Approved

Instruction Manual
© GE Grid Solutions
Attention!
Anyone involved in he ranspor a ion, ins alla ion, commissioning, opera ion, and main enance of
OTCF Capaci or Vol age Transformers (CVT) should read hese ins ruc ions before aking any
ac ion.
Never work on high vol age equipmen wi hou firs having grounded i s me allic par s, since i is
inheren o capaci ances he possibili y of elec ric charges accumula ed wi h vol ages a le hal
levels. In addi ion, an ear h rod mus remain connec ed o he line erminal while an opera or
works on hese ransformers.
When an elec rical es is going o be performed, he person responsible for supervising he es
assumes responsibili y for carrying ou he es in a safe manner in accordance wi h curren
legisla ion. Af er he es , he opera or mus remove he ground rod so ha he equipmen is
ready for opera ion.
Note: To discharge high vol age equipmen effec ively proceed as follows:
A) Connec he ground rod o he line erminal ( his will shor circui he en ire uni and place he
line erminal in he ground po en ial) and,
B) Use o her(s) ground rod connec ed o any in ermedia e me al par for a minimum of 30
seconds o make sure here is no residual elec rical load on he uni .
This ransformer is manufac ured wi h con rolled process which guaran ees he highes level of
Quali y. To main ain his high-Quali y level hroughou he service life of he CVT i is of he
u mos impor ance ha all ins ruc ions in his manual be read and unders ood.
THE VERSIONS O OTC TRANS ORMERS TRANSPORTED IN VERTICAL POSITION CANNOT BE
STORED IN THE HORIZONTAL POSITION. DEPENDING ON THE PRODUCT VERSION, OTC -245,
OTC -420 AND OTC -550 MAY BE TRANSPORTED AT HORIZONTAL POSITION. EVEN OR THESE
CASES, THE TRANS ORMERS CAN NOT BE STORED IN A HORIZONTAL POSITION OR MORE THAN
OUR MONTHS. I THE TIME O TRANSPORTION AND STORAGE EXCEEDS THIS PERIOD, IT IS
MANDATORY TO UNPACK AND PUT THE TRANS ORMER INTO A VERTICAL POSITION,
ANCHORING ITS BASETANK TO THE GROUND. DO NOT ENERGIZE A TRANS ORMER I IT HAS
BEEN KEPT IN HORIZONTAL POSITION DURING MORE THAN OUR MONTHS.
Preliminary remarks
During receip of he CVT, i is impor an o check he unpacking carefully o con rol he packaging
condi ions and he CVT i self. Any irregulari y mus be no ed on he ranspor a ion documen s and
communica ions wi h responsible persons should be made shor ly.
The insula or may be delivered in porcelain, avoid fas movemen s ha may cause shocks and / or
blows.

Instruction Manual
© GE Grid Solutions
Index
1. SCHEMATIC DIAGRAM ................................................................................................................ 5
2. TRANSPORT, RECEPTION, UNPACKING AND STORAGE .................................................................... 6
2.1. Transport ........................................................................................................................... 6
2.2. Reception .......................................................................................................................... 7
2.3. Unpacking .......................................................................................................................... 7
2.4. Storage ............................................................................................................................ 11
3. ANCHORING ............................................................................................................................ 11
4. CONTACT SURFACES PREPARATION ............................................................................................ 11
5. CONNECTIONS AND ACCESORIES ............................................................................................... 12
5.1. Primary terminals ............................................................................................................. 12
5.2. Secondary terminal box..................................................................................................... 13
5.3. Secondary terminals ......................................................................................................... 13
5.4. H terminal ...................................................................................................................... 13
5.5. Terminal marking ............................................................................................................. 14
5.6. Protection of compensation reactor and drain coil .............................................................. 14
5.7. CVT grounding .................................................................................................................. 14
5.8. EMU potential grounding switch ........................................................................................ 15
5.9. Carrier grounding switch ................................................................................................... 15
5.10. Line trap assembly ........................................................................................................ 16
6. OIL LEVEL INDICATOR................................................................................................................ 16
7. INSPECTION BEFORE FIRST ENERGIZING ...................................................................................... 17
8. ON-SITE TESTS ......................................................................................................................... 17
8.1. On-site test methods ........................................................................................................ 18
8.2. Care and precaution .......................................................................................................... 18
8.3. Capacitance measurement ................................................................................................ 18
8.4. Voltage ratio measurement ............................................................................................... 23
8.5. GARTON effect ................................................................................................................. 24
8.6. Capacitance and dissipation factor with temperature variation ............................................ 25
9. MANTENANCE AFTER ENERGIZING ............................................................................................. 25
10. FINAL DISPOSAL OF THE TRANSFORMER PARTS AFTER LIFE TIME ............................................... 26

Instruction Manual
© GE Grid Solutions
1. SCHEMATIC DIAGRAM
The OTCF Capaci or Vol age Transformer (CVT) is an assembly of a capaci ive vol age divider (CD)
and an elec romagne ic uni (EMU). Depending on he ra ed vol age, he CD may con ain of one or
more capaci ive modules wi h an in ermedia e vol age erminal hrough a medium vol age
bushing which feeds he EMU.
Each capaci ive module con ains capaci ive elemen s impregna ed wi h syn he ic oil and is
herme ically sealed, a me allic bellows works as expansion chamber o compensa e varia ion of
volume of oil due o ambien empera ure changing.
When specified, each capaci ive module can be supplied wi h a manome er for indica ion of
in ernal pressure of oil.
The EMU is moun ed in a ank filled wi h mineral oil and is herme ically sealed hrough an air
cushion.
Figure below shows a ypical cross-sec ional view of an OTCF:
1
-
Primary terminal
2- Top cover to protect metallic bellows
3- Metallic bellows
4- Compression spring
5- Wire for voltage connection
6- Capacitive elements
- Insulator: porcelain or composite
8- Voltage divider
9- Bushing
10- Voltage divider LV connection
11- Ferroresonance suppression device
12- Secondary terminals
13- EMU oil level indicator
14- Secondary box
15- Intermediate transformer
16- Oil / air block
1 - Oil sample plug
18- Compensation reactor
19- EMU top cover

Instruction Manual
© GE Grid Solutions
2. TRANSPORT, RECEPTION, UNPACKING
AND STORAGE
2.1. Transport
The ransformer shall be ranspor ed in
he posi ion indica ed by he
manufac urer in an appropria e
packaging.
In general, he CVT wi h maximum
vol age up o 245 kV is ranspor ed in a
wooden box con aining he assembled
base uni (EMU and CD). For CVT above
245 kV, he equipmen is ranspor ed in
such a way ha he upper modules of
he CD are separa ed from he lower
module and EMU bu ranspor ed in he
same package oge her wi h all he
necessary hardware for he assembly of
he comple e uni (see 5.1). The CD
modules must be placed in an upright
position. Depending on the product
version, OTC -245, OTC -420 and OTC -
550 may be transported at horizontal
position. Even for these cases, the units
cannot be stored in a horizontal
position for more than 4 months. It the
time of transportation and storage
exceeds this period, it is mandatory to
unpack and put the transformer in a
vertical position, anchoring its basetank
to the ground.
The user mus carry and handle he CVT
carefully. The correc shipping posi ion is
marked on he packaging as shown in
he following examples.
Example of ver ical packaging
Example of horizon al packaging
IMPORTANT: The OTCF mus always be
ranspor ed wi h he op modules
disassembled from he EMU. When
originally it was transported in
horizontal position, all components in
an upright position, apart from versions
that are transported in a horizontal
position. Also, i shall be ranspor ed in
i s original packaging or in an
appropria e packaging.
OTCF ver ical packages canno be
s acked. For horizon al packages, he
s ack limi is one.

Instruction Manual
© GE Grid Solutions
ATTENTION! The CVT has fragile par s
(insula or, bellows, e c.) ha can be
damaged during ranspor a ion, by sea,
air or by road (being he road paved or
no ). The ranspor a ion and handling
shall be made wi h care. Sudden
movemen s can cause impac and
damage o he equipmen .
2.2. Reception
Whe her he shipmen is on
manufac urer’s or cus omer’s
responsibili y, he cus omer inspec or or
he service agen has o check he
following on receip of delivery:
If he cra es show any signals of impac ,
blows or frac ures, or if he ransformers
have any signal of damage, or oil
leakage, he cus omer inspec or or he
service agen in charge of receip shall
make a wri en remark on shipmen
documen s. The receip con rol, mainly
for he porcelain insula ors and he
secondary erminal box, shall be done in
he presence of he forwarding agen , if
possible. The remarks regarding he
condi ion of he goods shall clearly s a e
de ails of he damages found a he ime
of recep ion.
In case of damages, he cus omer
inspec or in charge of receip shall no ify
GE and he insurance represen a ive. All
con ac informa ion shall be indica ed on
shipmen insurance documen s. This
declara ion shall be made wi hin
maximum of eigh days af er receip of
he ma erial.
2.3. Unpacking
Ma erial required for unpacking, lif ing
and pu he ransformer in o service:
Q y Descrip ion
2 Crane, munck or hois .
1 Con ac grease ype PENETROX or
equivalen .
1 Graphi e grease MOLYKOTE ype
P37 or equivalen .
4 Slings of 4,5m of leng h (capaci y
10.000 N)
1 Sling of 1,5m of leng h (capaci y
1.000 N), for cases wi h equipmen
packaged a horizon al posi ion only.
Unpacking of he ransformer should be
made wi h care.
Ver ical packaging
1) Remove upper cover.
2) Remove he smaller ex remi ies.
3) Remove he wood blocking pieces.
4) Remove he larger ex remi ies
5) Remove he four screws a he
equipmen fee and, when applicable,
screws ha anchor he modules o he
package
6) Lif each par of he CVT

Instruction Manual
© GE Grid Solutions
Example of wood blocking pieces
NEVER lift a transformer by its
primary terminal. Always lift it by
the four lifting holes on the
bottom tank and as per indicated
in the next pictures.
Horizon al packaging
1) Remove he upper cover.
2) Remove 3 side covers (excep he side
on which he base ank is fixed wi h
screws)
3) Remove he four screws a he
equipmen fee .
4) Remove he green nylon slings
5) Remove he CVT and lif i following
he nex s eps:
- Use wo slings, one a he neck of he
insula or and o her a he lif ing holes of
he base ank.
- Remove he CVT keeping i in horizon al
posi ion
- Gradually pu he CVT in ver ical
posi ion by lif ing he sling placed in he
neck of he insula or. Keep always he
sling in ver ical posi ion. Handle wi h
care in order do no damage he bellow
flange.

Instruction Manual
© GE Grid Solutions
- Af er confirming he CVT is in ver ical
posi ion and suppor ed in he ground,
change he lif sys em by four slings
placed a he four lif ing holes of he
base ank. Use a 1.5m sling o connec
he o her slings a he heigh of he
insula or neck o guaran ee he CVT will
no move horizon ally when lif ing.
CVT handled wi h i s package:
To lif he packaged ransformer wi h
crane or munck follow he marks on he
wood cra e, once i indica es he righ
posi ion for he slings (nylon bel s
reinforced) and avoid blows and
vibra ions. Handle wi h care!
Example of lif ing he CVT on i s packing
 Placing he CVT on he pedes al:
The use of lif ing slings or s eel cables
wi h a chocker ype hi ch arranged o
suppor he upper me al flange is an
effec ive way o lif he upper modules
of he CD.
Avoid sudden CVT movemen s when
lif ing. To avoid CVT ipping, i is
recommended o use a sling passed
around he upper flange of he insula or
and a ached o o her slings (one on
each side - see figure below).
If he CD of he CVT has more han one
sec ion, he op and bo om modules
mus be joined using he supplied
ma erial:
 Eigh or welve se s of bol s, nu s
and washers for each CD.
or OTC having manometer in the
CD:
The display box of he manome er used
in he sec ions of he CD are par ially
filled wi h liquid glycerin in order o
avoid any damage due o impac during
ranspor a ion. The glycerin is no
necessary af er ranspor a ion.
On he op of manome er, here is
rubber cover wi h a small pro rusion. or

Instruction Manual
© GE Grid Solutions
all OTC models, this small protrusion
needs to be cut after the
transportation. or the cases when CD
units are transported at horizontal
position, cut the protrusion only after
putting the CD at vertical position.
Follow he s eps below for moun ing on
he pedes al:
Place he CD op modules wi h heir
namepla es aligned o he main
namepla e, ins alled on he
secondary erminal box cover in he
base ank.
Place each module slowly, one a a
ime, wi h a crane.
Place he bol s in he upper uni
flange holes.
Fas en he bol s wi h an appropria e
orque (3 kgf.m).
Repea he same procedure for all
subsequen upper modules.
ATTENTION! I is manda ory for he
serial numbers of he CD modules o
ma ch he serial number shown on he
CVT main namepla e. Accuracy and
ferroresonance performance will be
affec ed if incorrec capaci ive modules
are assembled oge her.
The serial reac ance and ransformer
ra io are adjus ed and uned during he
fac ory rou ine es s o mee he
specified accuracy class. Each EMU is
uned o a CD. In his way, it is not
allowed o exchange any CD module or
even a comple e CD from one EMU o
ano her.
Example of lif ing
The base uni (or uni wi h only 1 module)
mus be handled using he 04 lif ing holes
available in he base ank. The use of the 04
lifting holes is mandatory.
4 lif ing eyes

Instruction Manual
© GE Grid Solutions
Moun ing on he pedes al
2.4. Storage
Transformers can be s ored packed
ver ically on a homogeneous surface.
NOTE: Equipmen s ored ver ically
exposed o he environmen , wi hou
packaging, mus be screwed o he
ground (fla and s able surface), even if
he s orage is of shor dura ion.
- It is not allowed to store
equipment horizontally.
3. ANCHORING
The ransformers mus be energized in an
uprigh posi ion. I is impor an o confirm
ha he surface on which he CVT is o be
fixed is fla ( olerance a mos 1mm). Check
ha all four fee are fully suppor ed on he
frame. If no , inser shims before fas ening
he screws.
Tank anchoring o he pedes al mus be done
using 4 (four) screws. The dimensions of he
holes and he hickness of he anchoring
poin can be found in he dimensional
drawing.
When a complemen ary base is supplied, he
ank mus be moun ed on his base and he
base anchored o he pedes al.
IMPORTANT: Never suppor ladders on he
equipmen for in erven ions a heigh s. Use
appropria e equipmen ha provides safe y
o he user.
An i-corona rings are provided only for
cer ain BIL values and radio in erference
vol age requiremen s. When supplied, i is
necessary o moun he corona-ring above
he flange of he upper module as shown in
he figure below. The an i-corona ring is
ranspor ed in he same package as he CVT.
Confirm in he se of CVT drawings if an i-
corona ring is applicable or no . Applicable
bo orque: 3,5 kgf .m (35 Nm).
4. CONTACT SUR ACES PREPARATION
I is recommended o clean all aluminum
con ac surfaces wi h sandpaper 150 grain o
elimina e he oxida ion layer. Scrub he
con ac surfaces wi h a me allic brush
(diame er of he hread 0,3mm) and
impregna e wi h grease of he ype
“PENETROX” or equivalen . All he surfaces
mus be comple ely covered wi h grease.
For silver or inned con ac s, only clean (do
no use sandpaper) and polish he side of he
aluminum. Cleaning silver or inned surfaces

Instruction Manual
© GE Grid Solutions
wi h sandpaper could cause damage o he
pro ec ion layer.
5. CONNECTIONS AND ACCESORIES
ATTENTION : Never work on a CVT wi hou
firs :
-Ground all me allic par s ( op, in ermedia e
and bo om CD) for a leas 30 seconds using
an appropria e grounding rod.
-Confirm ha all low vol age erminals
in ended o be grounded (N or H2, HF, 1n,
2n, 3n or X3, Y3, Z3) are effec ively grounded.
Before o reconnec vol age, confirm ha
here are no shor -circui ed secondary
erminals.
5.1. Primary terminals
Connec he high vol age cable or high
vol age ube o he primary erminal
of he CVT wi h an appropria e
connec or o ensure good con ac .
Check i em 4 of his manual for he
prepara ion of he con ac surface.
When he line connec ors are
supplied, he screws o connec he
connec or wi h he cable or ube are
no included in he scope of supply.
M12 or ½” bol s shall be used a he
primary erminals and flanges where
a minimum igh ening orque of 5,4
kgf.m (54 N.m) mus be applied.
No e: The screw hreads mus be
covered wi h MOLYCOTE P37 grease
(or equivalen ). Do no apply his
grease o con ac surfaces.
If he ranspor heigh allows, he CVT
is ranspor ed wi h he high vol age
erminal ins alled a he op of he
upper CD.
The orien a ion of he erminal can be
adjus ed by moving screws ha fix
primary erminal o he bellows flange
of he upper capaci ive module.
If he high vol age erminal is no
ins alled due o ranspor heigh
limi a ions, he erminal mus be
a ached o he uni using he
supplied ma erial:
Eigh or welve se s of bol s, nu s
and washers for each CD.
In his case, here will be a
me allic cover o pro ec he me allic
cell during ranspor a ion. This
pro ec ion shall be removed for he
primary erminal ins alla ion. Use he
bol s ha are available inside he
erminal box o a ach he op flange
and primary erminal.

Instruction Manual
© GE Grid Solutions
5.2. Secondary terminal box
Before opening he secondary
erminal box, check he posi ion of
he EMU and carrier grounding
swi ches. A warning pla e is supplied
wi h he CVT and is placed on he
secondary erminal box on he side of
he po en ial grounding swi ch.
5.3. Secondary terminals
Look for he se of drawings of he
CVT o verify he ype of connec ion
o he secondary erminal and
accep able cables for he connec ion.
Use proper connec ors o ensure a
good connec ion. Tigh ening orque is
indica ed on he secondary erminal
box drawing.
One poin of each secondary should
be connec ed o he ground erminal
inside he secondary erminal box, in
order o ob ain a ground poin for he
po en ial reference.
Unused secondary terminals must
remain open circuit and one point of
the unused secondary terminal must
be connected to the ground terminal.
This grounding should be done at
one point only, as far away as
possible from the CVT, preferably in
the control room. Multiple grounding
points may cause transient voltage
difference that can cause circulation
of surge currents between windings,
rather than flowing from the
windings to the earth.
When a secondary winding is used in
a broken del a connec ion wi h
secondary windings of CVT from o her
phases, ensure ha here is only one
grounding poin on he broken del a
connec ion as shown below.
NEVER SHORT CIRCUIT THE
SECONDARY TERMINAL O A
CVT .
5.4. H terminal
When available, for connec ion o he
carrier sys em, connec he lead-in
cable hrough he removable
undrilled gland pla e of he secondary
erminal box o he 'HF' erminal. The
figure below shows he ypical
posi ion of he 'HF' erminal. Confirm
he posi ion of his erminal in he
CVT secondary erminal box.

Instruction Manual
© GE Grid Solutions
If he carrier sys em is no connec ed
o he HF erminal during opera ion,
he carrier grounding swi ch mus
remain a he "Closed" posi ion. See
i em 5.9.
5.5. Terminal marking
The marking of he primary and
secondary erminals is done according
o he specified s andard for he
projec . Check he markings on he
se of approved drawings.
The wiring diagram for he secondary
erminals are hose shown on he
drawings.
5.6. Protection of compensation reactor
and drain coil
To provide pro ec ion agains
overvol ages arising from vol age
fluc ua ions in he CVT, pro ec ion
sparkers are supplied o he
compensa ion reac or and he drain
coil and are loca ed in he secondary
erminal box.
These sparkers may be of wo ypes:
Spark gap: Air insula ion wi h
prese fac ory se ing. Refer o
he CVT secondary erminal box
drawing for more de ails.
This setting cannot be modified
on-site.
Spark gap ype example
Encapsula ed: Gas insula ion
wi h pre-se opera ing vol age.
Refer o he CVT secondary
erminal box drawing for more
de ails on which ype is used.
Encapsula ed ype example
5.7. CVT grounding
The CVT ank has wo grounding
poin s loca ed on he ank's own
body. A leas one of he poin s mus
be connec ed o he subs a ion
ear hing sys em using appropria e
cables.

Instruction Manual
© GE Grid Solutions
When required, ear hing connec ors
are provided (check se of drawings o
see he ype of he connec or and he
range of cables i can receive).
Tigh ening orque of 5.4 kgf.m on
screw M12.
Example of ear hing erminal
Examples of ear hing connec ors
5.8. EMU potential grounding switch
When required, a po en ial grounding
swi ch is supplied wi h he CVT. I is
loca ed on he side of he ank.
Figure below shows he posi ion of
he po en ial grounding swi ch of he
EMU .
The opera ion ime wi h he po en ial
grounding swi ch mus be kep o a
minimum, since in his condi ion he
CD is subjec ed o a higher dielec ric
s ress by elimina ing he insula ion of
he capaci ance C2.
I is no recommended o remain wi h
he po en ial grounding swi ch closed
wi h he CVT energized for a long ime
(more han 6 hours).
5.9. Carrier grounding switch
If he carrier sys em is no connec ed
o he HF erminal while he CVT is
energized, he carrier grounding
swi ch loca ed on he side of he
secondary erminal box should remain
in he "Closed" posi ion as shown in
he figure below.

Instruction Manual
© GE Grid Solutions
5.10. Line trap assembly
If he CVT is used o suppor a line
rap, refers o he dimensional
drawing for more de ails.
An adap er pla e o fix line rap mus
be specified according o he
applica ion.
Verify dimensional drawing o ensure
ha he mechanical load imposed by
he line rap, including he forces due
o shor circui and wind, will no
exceed he values used a design
s age.
6. OIL LEVEL INDICATOR
For capaci ive modules or CD, when required,
oil level indica ors are provided. These
indica ors are manome er ype.
Figure below represen s he opera ing
posi ions of he indica or. If he indica or
(poin er) is in he green range he CVT can
remain, or en er, in opera ion. If he
indica or (poin er) is in bo h red ranges, i is
an incorrec opera ion condi ion for he CVT
and i mus be removed from opera ion and
GE mus be informed immedia ely.
Oil level indica or – ype manome er
For EMU i is s andard o provide an oil level
indica or. I is loca ed on he back of he ank
(opposi e side of he secondary erminal
box).

Instruction Manual
© GE Grid Solutions
EMU oil level indica or
7. INSPECTION BE ORE IRST ENERGIZING
• Confirm he erminal connec ions o ensure
correc igh ening orque on he fas ening
screws.
• Confirm ha here are no shor -circui ed
secondary erminals. If here are lef open
circui s and a poin connec ed o he
grounding erminal.
• Confirm he connec ion o he subs a ion
ear hing sys em.
• Confirm ha oil level indica or is in he
green area of he display.
• Confirm he pro rusion on he op on
manome er has been cu as explained in 2.3.
The CVT is es ed a fac ory according o he
s andard and does no require he repe i ion
of elec rical es s. Check rou ine es repor s
for more de ails. However, if i is desired o
carry ou some measuremen s, check i em 08
of his manual.
Al hough all care is aken a he fac ory
during oil filling, he surface around he
bellows and op cover screws can, wi hou
risks, show small oil s ains. These s ains
should no be confused wi h oil leakage if he
level indica or poin er is posi ioned in he
green area of he display. Clean hose s ains
wi h alcohol and confirm ha here is no oil
leakage.
DO NOT REMOVE OIL SAMPLES ROM THE
CAPACITIVE DIVIDER.
NO REMOVAL O OIL SAMPLES OR
ANALYSIS IS NECESSARY OR THE EMU. CVT
IS HERMETICALLY SEALED.
If necessary, EMU oil samples, small
quan i ies may be aken. Always check he oil
level indica or before aking he samples.
Never refill oil without consulting GE.
8. ON-SITE TESTS
If cus omer uses a periodic main enance
program ha includes elec rical
measuremen s, he following es s are
recommended as a guide.
I is impor an o use capaci ance me ers ha
can perform readings wi h a minimum
accuracy of 0.5%.
The nominal values of he capaci ances
expressed in pF (pico-Farad) are recorded on
he namepla e of he CVT.
Measuremen s performed during
commissioning should be kep as a reference
for subsequen measuremen s.
An increase of abou 1% in he capaci ance
values should be carefully checked, as i may
be an indica ion of failure of insula ion of a
capaci ive elemen .

Instruction Manual
© GE Grid Solutions
Important notes: During he commissioning
es s, he record of he values found for each
ype of es performed shall be made for
comparisons wi h he resul s ha will be
measured during he life ime of he CVT. The
values measured in he fac ory es s are
impor an , bu also impor an are he resul s
of he commissioning, for each CVT. The
comparisons be ween he resul s of he es s
make sense for he da a measured in he
field, since hey de ermine he moni oring
and evolu ion of he values and he
performance of each CVT, when a his ory of
heir life ime can be ob ained.
8.1. On-site test methods
In general, on-si e es equipmen can
provide a es vol age of up o 10 kV
for measuremen purposes. The
procedures and echniques are no
he same for differen es
equipmen . Check he opera ing
manual of he es sys em. The
precau ions and es principles given
below are for reference.
8.2. Care and precaution
• Before handling capaci ive uni s,
shor circui and ground hem for a
leas 30 seconds o avoid any
possibili y of s ored loads.
• The maximum vol age ha can be
applied o he carrier erminal cable
af er removal from he "HF" erminal
(CD low vol age erminal) is 2 kV.
• The maximum vol age ha can be
applied o he ground erminal of he
EMU ("N" or "H2") af er removing i is
2 kV.
• The nominal vol age of he
in ermedia e vol age erminal (or
nominal vol age of he EMU) is
indica ed on he namepla e of he
CVT. I is recommended ha he
lower capaci or capaci ance
measuremen be performed a a
vol age less han 10% of he ra ed
vol age of he lower CD.
• Af er removing he "HF" and "N" or
"H2" erminal connec ions, do no
energize he uni a ra ed vol age.
• Apply he vol age in a con rolled
manner.
• Redo any connec ion ha has been
removed during he on-si e es s.
8.3. Capacitance measurement
The following figures show how o
connec ypical insula ion
measuremen equipmen for he
measuremen of each capaci ance of
an OTCF CVT.
Since he in ermedia e vol age
erminal of he lower capaci ive
module for accessing he capaci ances
C1-1 and C(2) is no direc ly
accessible, he user can de ermine
he o al capaci ance from he
measured values of C1-1 and C2.
The presence of he in ernal chock
coil does no influence he
measuremen s for frequencies of
50Hz or 60Hz.
 CVT with capacitive divisor in a
single module

Instruction Manual
© GE Grid Solutions
Figure 1 – Capaci ance measuremen of C1 –
OTCF single module (Mode GST/Ground)
Figure 2 - Capaci ance measuremen of C2 –
OTCF single module (Mode GST/Ground)
 CVT with capacitive divider
with two modules
Figure 3 - Capaci ance measuremen of C1-1 – OTCF
wo modules (Mode GST/Guard)
Figure 4 - Capaci ance measuremen of C1-2 – OTCF
wo modules (Mode UST)
 CVT with capacitive divider
with three modules

Instruction Manual
© GE Grid Solutions
Figure 5 - Capaci ance measuremen of C1-1 – OTCF
hree modules (Mode GST/Guard)
Figure 6 - Capaci ance measuremen of C1-2 – OTCF
hree modules (Mode UST)
Figure 7 - Capaci ance measuremen of C1-3 – OTCF
hree modules (Mode GST/Guard)
 CVT with capacitive divider
with four modules