Arteche DDB Series User manual

USER MANUAL
CONTENTS
PRELIMINARY CONSIDERATIONS
INTRODUCTION
TRANSPORT AND HANDLING
INSTALLATION
INSPECTION AND MONITORING QUICK
TROUBLESHOOTING GUIDE
ANNEX I
ANNEX II
ANNEX III
HIGH VOLTAGE INSTRUMENT TRANSFORMERS
DDB/DFK
DDN/DFN

1High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
OBSERVATIONS/
Keep the instruction manual in a safe and accessible place
to ensure that any operation or maintenance task can be
performed quickly and easily when necessary.
For safety reasons, only qualified sta can use this equipment.
Read the instruction manual and other documentation before
the equipment’s installation, commissioning and maintenance.
Become familiar with all equipment information and safety
precautions before using the equipment and during its
operation.
Always use the equipment within the guidelines indicated in
the instruction manual and in other relevant documents.
In order to prevent malfunctions, carry out proper controls and
maintenance.
Do not use or handle the equipment in a manner contrary to
what is expressly stated in this manual, do not modify the
equipment with parts from other manufacturers. This behavior
can lead to damage to the equipment and/or personal injury.
ARTECHE is not liable for accidents due to causes unrelated to
our guidelines.
In the event of equipment malfunction or any other type of
problem, communicate it immediately to the corresponding
ARTECHE department, providing the following information:
› Evaluation of contents and the product’s nameplate (name,
serial number, type and date of manufacture).
› Description of the problem (as detailed as possible, including
the situation immediately before and after the problem
occurred) and supporting photos or videos.
If you have any questions, please contact www.arteche.com.
› Europe, Africa & Middle East:
[e-mail]
› Asia (except Middle East) and Oceania:
[e-mail]
› North America, Central America and the Caribbean:
[e-mail]
› South America:
[e-mail]
PRELIMINARY CONSIDERATIONS
DANGER/
CAUTION
Indicates that improper use o
handling may result in physical
damage to the equipment,
serious injury or even death
SAFETY PRECAUTIONS/
For safety reasons, only qualified personnel can carry out
maintenance and commissioning or operation.
Read the instruction manual and other documents before using
the equipment. Become acquainted with every aspect of the
equipment and its safety precautions before using it.
Do not use, handle or modify the equipment in a way that is not
expressly stated in these operating instructions and do not use
or modify the equipment with parts from other manufacturers.
The safety precautions used in this manual are indicated by the
following message:
Depending on the situation, mishandling can have serious
repercussions, even when “Caution” is indicated in this
instruction manual. Strictly observe all security measures.
These safety precautions are the manufacturer’s suggestions to
ensure the safety of the equipment.
Users are requested to establish security measures so as to
maintain safety and the equipment operating in accordance
with various standards and requirements.
ARTECHE will not be liable for accidents caused by not carrying
out the safety measures.
ENVIRONMENTAL CONSIDERATIONS/
Disposal considerations:
Disposal or recycling will be carried out in accordance with
current legislation. Oil and impregnated products shall be
disposed of through an authorized manager in authorized plants.
They can be incinerated in suitable plants, respecting local
regulations. The oil is free of PCBs and chlorinated products.
More information on the oil safety data sheet. The metals are
recyclable (copper, steel, aluminum, silver, etc.).
Measures to be taken in the event of an oil spillage:
Prevent the oil from spreading or getting into the sewage
system, ditches or rivers by using sand, absorbents or other
appropriate barriers. Collect the oil with an absorbent material
and send it to appropriate containers for disposal, in accordance
with local legislation. Oil is not easily biodegradable. It contains
components with bioaccumulation potential.

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High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
INTRODUCTION
FOREWORD/
This manual describes the construction, installation, commissioning and monitoring for safe use of a high-voltage instrument
transformer insulated by oil-paper.
SCOPE OF APPLICATION/
The manual applies to the following transformers:
›Capacitive Voltage Transformers, DDB Series, Models: DDB-72..170.
›Capacitive Voltage Transformers, DFK Series, Models: DFK-245..765.
›Coupling Capacitors, DDN Series, Models DDN-72..170.
›Coupling Capacitors, DFN Series, Models DFN-245..vvz765.
DESIGN/
Capacitive voltage transformers consist of 1 or more capacitor
units mounted on a tank containing the electromagnetic unit
(intermediate transformer, compensation reactance and
auxiliary elements).
The tank is fitted with a box containing the secondary terminals
and the adjustment compensations (they are protected by a
sealed cover).
Oil volume variations in the capacitor unit(s) are compensated for
in one or more metal diaphragms located at the top of each unit.
In the inductive part (tank), the oil level is displayed by a direct
indicator. Each insulator is hermetically sealed and independent.
The coupling capacitors have the same characteristics as
previously indicated for capacitive voltage transformers but
without the electromagnetic unit (EMU).
1. Primary terminal
2. Oil volume compensating system
3. Insulator
4. Capacitors
5. Intermediate voltage tap
6. Inductive voltage transformer
7. Secondary terminal box
8. Upper Capacitor Unit
9. Intermediate Capacitor Unit
10. Lower Capacitor unit
11. Electromagnetic Unit (EMU)
12. Carrier accessories (on demand)
1
3
5
6
7
2
2
3
4
4
8
10
9
11
12

3High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
TRANSPORT/
TRANSPORT AND HANDLING
ARTECHE’s packaging guarantees a correct transport to
destination.
Transport must always be carried out in a vertical position, in
wooden boxes.
If the transformer is made up of several capacitor units, it is
shipped disassembled, with all the capacitor units inside the
same box, each one anchored to the base of the packaging,
except the lower one, which is attached to the tank.
For transport, the transformer should be properly attached to
the packaging so as to avoid movement.
› Load and unload the transformer slowly and avoid sudden
movements.
› It must be secured to the truck to avoid movement.
› Keep truck acceleration under 5G, and the speed under:
• Unpaved road ___________ Max. 30 km/hour
• Secondary roads ___________ Max. 30 km/hour
• Highway (Motorway) ___________ Max. 30 km/hour
STORAGE/
The storage area must maintain the necessary health and safety
conditions so as to avoid damage to the transformer. Follow the
safety markings on the packaging at all times.
› Always store in an upright position: The transformers must be
stored upright in their original packaging, which was designed
to this end.
Wooden packaging loses its properties over time, especially
when exposed to the elements.
Therefore, transformers cannot be stored in their packaging
indefinitely. This period depends on the type of wood,
temperature, humidity, contamination, etc. It is recommended
to check the integrity of the packaging regularly.
After unpacking the transformers, if they are not to be installed
immediately, always store them firmly anchored to the ground
without time restriction.
The final holder will be responsible for delivering the used
packaging or its waste for environmental management according
to the legislation in force in their country.
HANDLING/
It is recommended to transport the packaged transformers to
the construction site.
Unpacking: Remove the top and sides of the box to allow free
handling of the unit.
Annex I, contains the figures mentioned below.
The movements are to be carried out as shown in fig. 1.
For transformers consisting of a single capacitor unit, the slings
must be placed in the holes prepared for this purpose in the
base and, before lifting, the screws that join the unit to the base
of the packaging must be loosened.
DANGER
INJURIES from falls and tipping
› Do not place the equipment upside down or on its side
› Do not transport the equipment in conditions other than those mentioned
RECEIPT/
After receipt, check the packages for signs of shock, tampering,
etc. Any anomaly must be indicated on the transport
company’s receipt sheet and communicated to ARTECHE or
the equipment supplier.
Once the transformer has been unpacked, check that none of
the screws holding the insulator have become loose during
transport. If they have, tighten them according to the torque
indicated in Annex II. If any other type of anomaly appears,
inform ARTECHE or the supplier of the equipment.
Attach pictures of the damaged transformers with the report.
› Possible damage to the packaging: Dents on the outside, open
packaging, etc.
› Possible damage to equipment: Broken or defective insulator,
dented metal parts, damaged secondary terminal box, etc.
The packed units can be moved by forklift or with slings and/or
chains. Follow the safety markings on the packaging.
DANGER INJURIES AND/OR FIRE
› Do not use damaged equipment
DANGER
INJURIES from falls and tipping
› Do not place the equipment upside down or on its side
› Handle the transformer according to the instructions in this manual
› A sling which is in good condition and is suitable for handling the equipment should be
used according to the equipment’s weight, indicated on the nameplate
Under no circumstances should a transformer be manipulated by pulling on the primary terminals
This may cause damage to the equipment and void its warranty
For multiple capacitor units, never move the entire unit suspended by its head. Always move it from the base (tank)
fig. 1a, fig. 1b

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High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
INSTALLATION
MOUNTING ON THE STRUCTURE OR PLATFORM/
Check the information on the nameplate to verify that the
electrical characteristics match those of the system.
Carefully check that all four legs of the transformer are perfectly
placed on the platform before tightening the anchor bolts.
If this is not the case, correct the defect, by wedging metal
plates or similar. Failure to do so may result in insulator breakage
or oil leakage.
The slings must be attached to the upper flange area of the
insulator to prevent it from tipping over during the operation
(see fig. 1b).
DANGER
INJURY AND/OR FIRE
› Do not install the equipment without following our specifications
› Use the transformers under proper service conditions and according to specifications
› Do not loosen any screws or fastening nuts, it can cause oil leaks
ELECTRICAL DISCHARGE
› Do not wire or connect when the equipment is in operation
› The ground terminal of the apparatus must be solidly earthed by means of a connection capable
of withstanding and conducting the line’s fault current to earth.
› Do not short-circuit the secondary circuit of the transformer
Indications for units consisting of several capacitor units:
› For the lower unit, proceed as described above.
› For all other capacitor units, the slings are to be tied to the
upper flange of the isolator (see fig. 1c) or to the eyebolts of
the cover (see fig. 1d).
Only the fastening screws in the packaging must be loosened as shown in fig. 2, otherwise the tightness will be
broken and oil will leak out
Once the equipment has been unpacked, a visual inspection is
suggested so as to detect possible oil leaks or stains.
Oil stains are not necessarily the result of a leak. In most
cases, the stains are nothing more than oil residues from the
manufacturing process.
The stain should be cleaned with a degreaser and the equipment
should be kept under observation. If the stain reappears or
spreads, contact the manufacturer.
TRANSFORMER MOUNTING (when the unit consists of several capacitor units)/
The assembly of the transformer made up of several capacitor
units must be carried out on the structure in the following
sequence:
1. Lower capacitor unit:
› Remove the protective cover of the compensators from
the upper part (fig. 3), keeping the nuts for subsequent
attachment of the upper unit.
› Lift it onto the structure as described in the handling section
and fig. 1b.
2. Intermediate capacitor unit (if any):
› Remove the protective cover of the compensators from
the upper part (fig. 3), keeping the nuts for subsequent
attachment of the upper unit.
› Only the screws that connect the unit to the base of the
packaging should be loosened. The unit is now ready to be
lifted (fig. 2).
› To lift it as described in the chapter on handling and fig. 1c
and fig. 1d.
› This unit is placed on top of the lower unit by connecting the
cable between the two to the threaded hole at the bottom
of the upper unit by means of the screw provided (fig. 4.)
Both units are to be coupled with the stud bolts that have
become free after removing the protection disc (fig. 5.) The
tightening torques are given in Annex II.
3. Upper capacitor unit: Proceed as in point 2 (Not applicable
the point regarding the protective cover).
Do not forget to make the electrical connections between the capacitor units
Check that the serial numbers on the same transformer match
If an already installed unit is disassembled, proceed in the
opposite way to that indicated, not forgetting to fit the short-
circuit cable to all the capacitor units.
Keep the grounding switch of the carrier accessories (if
applicable) in the closed position.

5High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
ELECTRICAL CONNECTIONS/
Primary connections
The primary terminal material is aluminum or copper. They can
have a tin or silver coating to prevent galvanic pair corrosion and
improve their contact.
Do not bring aluminum into contact with copper-based materials
unless special precautions are taken.
Material Finish Cleaning
Copper
Silver or tin plated We recommend cleaning the contact surfaces with
a soft cloth (avoid brushing with a metal brush)
Aluminum
Aluminum
Unfinished
We recommended vigorously brushing the contact
surfaces with a soft metal brush (preferably
stainless steel) or sandpaper, until you see the
characteristic shine of the clean metal
Copper/Brass
Only impregnate the contact surfaces to be used with contact
grease, keeping the others clean. Remove excess grease to
avoid contamination.
Tightening must be carried out using a torque wrench, as shown
on the diagram plates and in Annex II.
Check the correct external wiring.
Grounding
The ground terminal of the transformer must be properly
connected to the ground network by a connection capable of
carrying the network’s fault current. Check that the connection
is tightened correctly and that the contact surfaces are clean.
The low voltage terminal of the primary voltage winding must
always be grounded when the transformer is in service. This
terminal can be located inside the secondary terminal box on
the side of the box (fig. 7).
The high-frequency terminal (HF), which protrudes from
the capacitor unit, must be firmly connected to the ground
terminal of the housing (fig. 8a). If there are carrier accessories,
this high frequency (HF) terminal shall be connected to the
carrier accessory block. While this equipment is not in use, the
grounding switch must remain closed (fig. 8b).
A faulty contact or a bad connection can lead to rapid transformer deterioration
Avoid excessive torque, as the connector may suer damage such as cracks which may expand in the future and
cause it to break
An inadequate torque may cause improper contact and cause the terminals to heat up during operation
Secondary connections
The secondary winding(s) must be connected to earth through
one of its terminals, preferably in the secondary terminal box
itself.
In case of secondary with intermediate taps, the common termi-
nal must be grounded.
Check that the secondary connections are correctly tightened
and the contact surfaces are clean.
The screws of the lower cable gland cover, the block cover
and the terminals must be tightened to the torque specified in
Annex II.
Do not leave the terminal block open after handling. It should
be properly closed with the cover and lid.
In the terminal box there is a block where the secondary wires
are connected. The disposition of the terminals is indicated on
the secondary marking plate on the inside of the box cover.
Any secondary one that is not loaded must be open and grounded at a single point
The current in a short-circuited secondary can reach dangerous values and can even destroy the device
CAUTION
Do not use the secondary terminal block as a step
A platform lift or ladder should be used to make or check the primary connections,
upholding the necessary safety conditions for work at height. Under no circumstances
may the terminal block be used as a support

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High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
Always follow the Arteche Manual for instructions on transport,
storage, handling and installation.
ARTECHE instrument transformers do not require maintenance.
There are no moving parts and no components susceptible to
wear and tear, so no active maintenance is required.
However, some companies perform some maintenance
operations on instrument transformers as part of a general
substation maintenance program. These maintenance programs
are not intended to extend the life of the units, as the measures
have no impact on the state of the insulation or the performance
of the units. These programs serve to know the state of the
isolation, so that the user can make decisions based on the
results obtained, as well as detect situations that may be causing
damage to the unit.
We at Arteche, as manufacturers, do not establish any specific
measures, since the decision depends on:
›the resources available to each user,
›the location of the instrument transformer (can be a position
which is more or less critical),
›the environmental and electrical conditions that the unit must
withstand at each specific point,
›the history of the unit,
›the specific types or the problematic units,
›etc…
The following inspection points are only a suggestion in case
they are within the user’s maintenance policy.
1. Physical inspection:
a. a. Mechanical: Look for signs of impact, damage or loose
parts.
b. Electrical: Check the correct state of the electrical
connections.
c. Oil: Look for oil leaks and check the oil level.
2. Dielectric tests:
d. Electrical tests to evaluate the insulation of the equipment.
For the test procedure, see Annex III.
3. Thermographic testing:
e. Use of thermographic cameras.
ARTECHE oers a diagnostic service for capacitive voltage
transformers in the field. More information: www.arteche.com.
INSPECTION AND MONITORING
DANGER
ELECTRIC SHOCK AND/OR INJURY
›Everything should only be carried out by personnel who is qualified in the maintenance and verification
of the equipment
›Do not touch live parts
Final Considerations
DANGER The transformer must be firmly grounded. A faulty or missing connection may cause damage or even
destroy the device
Once the installation has been completed, the short-circuit cable must be removed from each capacitor unit before
energizing the transformer (see fig. 9.) This cable is used to prevent the capacitor from being charged during storage
and handling
If the transformer is equipped with a grounding switch for the electromagnetic unit, it should only be used for
maintenance purposes. It is not intended for permanent earthing of the electromagnetic unit in operation, as the
insulation of the capacitor part would be reduced (fig. 10)
Resin block:
›Transformer adjustment taps and ferroresonance protection
circuit connection links, covered by a protective cap which is
sealed at the factory. Do not open the box.
›The main protection circuit is located on the protection cover,
connected to the terminals “RS1” and “RS2” marked on the
block itself. Important: This main protection circuit must be
always connected.
[1] [2]
[3] [1]
[3]
1. Protective cover for adjustment taps.
2. Main ferroresonance protection circuit (only accessible for the resin block).
3. Precinct.
Metal block:
›Transformer adjustment taps and ferroresonance protection
circuit connections, covered by a protective cap which is
sealed at the factory. Do not open the box.
The following elements are located on the right side of the terminal block:

7High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
Type Code Test Observations
Physical inspection
A1 Packaging Look for signs of rough handling.
A2 Insulator Check that is not damaged and is clean. Check that it is not loose, bent or broken.
A3 Primary
Terminals Check that they are not loose, bent or broken.
A4 Secondary
Terminal
Box
Check that it is not damaged and that it is securely fastened to the tank or transformer holder.
Check that no water enters the terminal box due to rain.
Check that the ventilation openings are not blocked.
A5
A6 Metal parts Check for dents, scratches or signs of corrosion.
A7 Unusual
behavior Check for unusual noises, vibrations or odors.
B1 Primary
connections
Check that there is good contact, that there are no signs of corrosion and that all nuts and bolts are
properly tightened. The use of conductive grease such as Penetrox A13 is recommended to improve
contact.
B3 Secondary
circuits
Check that all screws are properly tightened, and that there are no signs of corrosion.
In the case of secondary windings with intermediate taps, check that the connection matches the real
transformer ratio.
Check that the unused secondary windings are in open circuit.
B4 Grounding Check that the grounding terminal is correctly connected to the substation grounding network, that
the screws are correctly tightened and that there are no signs of corrosion.
B6
Voltage
transformer
neutral
connection
Check that the neutral terminal (N) of the primary winding is grounded.
Leaving it open when the transformer is energized will cause surges and damage to the
transformer.
B7 Readings Check that the reading values of the secondary match the values expected.
B8 AF connection Verify that the high frequency (HF) terminal is connected to ground or to the accessory block. While
this equipment is not in use, the carrier wave groundings witch must remain closed.
C1 Oil level
indicator Check the oil level in the tank through the sight glass.
C2 Oil stains
or leaks
Check the following areas for visible oil traces:
› Insulator flanges
› Junctures between parts of the metal enclosure
› Junctures between the secondary terminal box and the tank or base
› Primary terminals’ surrounding area
Dielectric tests
D1 PF/DDF/tgδ
The limit values of this parameter depend on the transformer’s voltage level. The recommended values
are given with the order. It is also important to control this parameter’s change over time. A change
in the value of this parameter indicates a change in the properties of insulation, but it is not definitive
proof of faulty insulation. For this reason, if the value of the delta tangent is above the recommended
value or has increased, a careful investigation should be carried out and further testing may be required.
In this case, contact Arteche for assistance.
For details on the test procedure, follow Annex III.
D2
Measurement
of the
Insulation
resistance
For field tests, the use of the megohmmeter (Megger) is very common, and the tests that are usually
done are:
› N/P2 against secondary and Ground
› Each secondary against ground
› Among the secondaries
In the case of new equipment, the value obtained does not provide any information, unless a short circuit
is detected. Generally, values above 200 MΩshould be expected. However, the comparison of long-term
values - such as in the case of tanδ, or of power factor - can help determine if a device is still in good working
conditions.
Do not test at voltages above 3 kV AC or 1 kV DC.
Do not test for more than one minute. It is not recommended to repeat this test often as the
internal insulation could be damaged.
For details on the test procedure, follow Annex III.
D3 Ratio test
The Portable Transformer Ratio Meter is commonly used to measure the ratio, excitation current and
polarity of windings. The values obtained are a reference that the transformer is in good condition
and can be energized. They should not be compared with the results of factory tests carried out in the
manufacturing plant laboratory.
Due to the high precision required for this measurement, the actual uncertainty of the test must be
taken into account when testing on site.
For details on the test procedure, follow Annex III.
Thermographic
tests
E1 Thermographic
analysis
Using thermographic cameras, hot spots can be detected during the operation of transformers. In
most cases, hot spots on instrument transformers occur at the primary terminals’ connection point to
the line. If present, check the integrity of the connectors, as well as their correct position and whether
they are correctly tightened.

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High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
User manual
TESTS PROGRAM/
CAREFUL CHECK OF THE TRANSFORMER/
It is recommended that all regular tests be repeated after a
long period of operation (about 20 years), or if a major network
disturbance has occurred that could damage the transformer
(e.g. a short circuit with current or duration values higher
than the nominal ones, or over-voltages caused by the
malfunctioning of the switches).
QUICK TROUBLESHOOTING GUIDE
Phenomenon Cause Countermeasure
Oil stains
Oil residues from the
manufacturing process
Clean the area and keep it under observation
for 24 hours. If the stain does not reappear,
the device can function normally. If the
leak persists, contact ARTECHE
Loose junctures
Tighten the screws and bolts, clean the
area and keep it under observation.
If the leak persists, contact ARTECHE
Cracks or damage to components Contact ARTECHE
Non-visible oil level Oil leakage or overpressure Remove the transformer from
service and contact ARTECHE
Cracks in resin parts Blows or improper handling Contact ARTECHE
When What
On arrival of the transformers at the warehouse or substation A1
After unpacking A2 - A3 - A4 - A6 - C2
During assembly A2 - A3 - A4 – A5 - A6 - B1 - B3 - B4 - B6 - B8 - C1 - C2 - D2 - D3
After energizing A7 - B7 - C1 - C2 - F1
Routine checks (weekly or monthly) A2 - A7 - B7 - C1 - C2
Annual verifications A2 - A3 - A4 - A5 - A6 - A7 - B1 - B3 - B4 - B6 - B7 - B8 - C1 - C2 - F1
Every five yea Same as annual + D1
After re-connections, load changes A7 - B1 - B3 - B4 - B6 - B7 - B8 - F1
After the fault conditions, the short circuits, etc. A3 - A7 - B1 - B3 - B4 - B6 - B7 - B8 - C1 - C2 - D1
See also “Careful check of the transformer” below

User manual - Annex I High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
ANNEX I
›DDB-72..170
HANDLING AND CONNECTION
›DFN-245..765
›DFK-245..765 ›DDN-72..170

1
User manual - Annex I
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
1a 1b 1c 1d
›Fig. 2: Loosen only these screws
›Fig. 1: Handling
FIXING SCREW
4 FIXING SCREWS
DO NOT TOUCH - OILTIGHTNESS DO NOT TOUCH - OILTIGHTNESS
THE UNIT IS FIXED
BY MEANS OF THE
4 FIXING SCREWS
4 NUTS ARE USED TO FIX IT
TO THE PACKAGING.
REMOVE THEM FOR
UNPACKING

2
User manual - Annex I
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
›Fig. 3: Protective cover
›Fig. 5: Assembly between capacitor units
›Fig. 4: Connection cable for capacitor units

3
User manual - Annex I
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
›Fig. 6: Level indicator ›Fig. 7: Neutral grounding connection
›Fig. 9: Short-circuit cable of capacitor unit Remove only before energizing ›Fig. 10: Grounding switch
›Fig. 8b: HF connection with carrier accessories›Fig. 8a: HF grounding without carrier accessories

User manual - Annex II High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
ANNEX II
SCREW
TYPE
TORQUE WRENCH SETTING (Nm)
USE TORQUE WRENCH SETTING
M12/16/20 Fixing the insulator to the base 30 Nm
M12 Support between capacitor units 30 Nm
M12 Insulator flange to intermediate plate 30 Nm
M6 Connection cable between capacitor units 12 Nm
M8 Tank Lid 30 Nm
M8 Primary Terminals 20 Nm
M8 Secondary terminals (if they are of the screw type) 12 Nm
M6 Grounding (inside secondary terminal box) 12 Nm
M10 HF terminal 12 Nm
M6 Cable gland 12 Nm
M8 Terminal Block Cover 20 Nm
M6 Bottom closing lid of the terminal block 12 Nm
TIGHTENING TORQUES
NOTE: If a torque dierent from that indicated in this table is indicated on the drawing or plates of the equipment, the torque indicated on the drawing
or plate must be applied.

User manual - Annex III High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
ANNEX III
ELECTRICAL FIELD TESTING
All ARTECHE transformers are assessed at our High Voltage laboratories, under the strictest criteria of international standards and/or
under specific client standards/specifications when so requested. All of it under a thorough quality system, certified under ISO 9001.
However, it is normal for pre-operative tests to be performed in order to confirm certain important equipment values. The following
is a guide to the most common on-site tests and the proper way to perform them on ARTECHE brand transformers.
This annex applies to the following equipment:
› Capacitive Voltage Transformers, DDB Series, Models: DDB-72..170.
› Capacitive Voltage Transformers, DFK Series, Models: DFK-245..765.
› Coupling Capacitors, DDN Series, Models DDN-72..170.
› Coupling Capacitors, DFN Series, Models DFN-245..765.

6
User manual - Annex III
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
MEASUREMENT OF CAPACITANCE AND DIELECTRIC DISSIPATION FACTOR (tanδ)
The purpose of this test is to assess the insulation of the HV
transformer.
NOTE: Field testing of tanδmay be susceptible to dierences
in measured values from factory testing due to the following
factors:
› The type of test equipment used and the measurement voltage
level.
› Thermal conditions (high humidity, rain, pollution).
› Temperature of the test object.
› Stress induced to the test object through other equipment.
It is recommended that the surfaces of the transformer (insulators
and others) be clean, to avoid external leakage currents.
Test instruments for field use are usually equipped with solutions
to compensate for external leakage current. The voltage test
for this particular equipment is typically 10 kV for high voltage
insulation and approximately 2.5 kV for low voltage insulation.
Ta n δand capacitance measurement can also be performed in
the field using other low voltage test bridges and a transportable
high voltage test set capable of measuring voltages up to the
nominal voltage. The choice and application of various test
equipment is at the discretion and experience of the user.
In addition to the measurement of tanδ, the measuring
equipment can usually also measure other parameters such as
capacitance and power factor.
The delta tangent measurement is carried out with the same
layout as the capacitance measurement.
Measurements can be made of tanδand capacitance of the
capacitor unit(s), Cn, C1 and C2.
All measurements must be made with the equipment switched
o and with a test voltage <10 kV for measurements Cn and C1
and <2 kV for measurement C2.
Cn - Total rated capacitance
The rated capacitance Cn of the unit is the capacitance value
between the high voltage terminal (number 1 in fig. 1) and the
low voltage terminal (number 3 in fig. 1.)
The capacitor voltage divider is designed to meet the rated
capacitance Cn.
This value, with some tolerance allowed, is engraved on the
nameplate.
The value of Cn is calculated with the following formula:
Cn=(1∗2)/(1+2)
Test procedure (fig. 2):
› Disconnect the HF connection to ground.
› The (HV) power cable of the measuring equipment must be
connected to the primary terminal (A/H1).
› The measurement cable must be connected to the high
frequency terminal (HF).
C1 - High voltage capacitance
The high voltage capacitance C1 corresponds to the part of the
capacitor connected between the line terminal (number 1 in the
fig. 1) and the intermediate voltage terminal of the capacitive
divider (number 2 in fig. 1).
This test can only be performed in the field if the transformer
has a grounding switch, since point 2 is not directly accessible
because it is inside the lower capacitor unit. For that reason, the
way to measure this capacitance is to close the grounding switch,
thus short-circuiting the electromagnetic unit and connecting
point 2 in the figure to ground. The measurement will be made
directly between the high voltage terminal (number 1 in fig. 1)
and the transformer tank or transformer ground.
Test procedure (fig. 3):
› Disconnect the HF connection to ground.
› Close the grounding switch.
› The (HV) power cable of the measuring equipment must be
connected to the primary terminal (A/H1).
› The measuring cable must be connected to the ground terminal
of the transformer.
C2 - Capacitance of the intermediate voltage capacitor
The capacitance of the C2 intermediate voltage capacitor
corresponds to the part of the capacitor connected between the
intermediate voltage terminal of the capacitive divider (number
2 in fig. 1) and the low voltage terminal (number 3 in fig. 1).
This test can only be performed in the field if the transformer
has a grounding switch, since point 2 is not directly accessible
because it is inside the lower capacitor unit. For this reason,
the way to measure this capacitance is to close the grounding
switch, thus short-circuiting the electromagnetic unit and
connecting point 2 in the figure to ground. The measurement
will be made directly between the low voltage terminal (number
3 in fig. 1) and the transformer tank or transformer ground.
Test procedure (fig. 4):
› Disconnect the HF connection to ground.
› Close the earthing switch.
› The power supply cable (HV) of the measuring instrument
must be connected to the high frequency (HF) terminal (low
voltage terminal).
› The measuring cable must be connected to the ground terminal
of the transformer.
CAPACITIVE VOLTAGE TRANSFORMERS AND COUPLING CAPACITORS/

7
User manual - Annex III
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
Capacitance of each capacitor unit
The capacitance of each capacitor unit can be measured directly
between the flanges of the insulators, with the exception of the
bottom insulator.
Test procedure for intermediate capacitor units or higher:
› The power supply cable (HV) of the measuring equipment must
be connected to the higher flange or the primary terminal.
› The measuring cable must be connected to the lower flange of
the capacitor unit.
Test procedure for the lower capacitor unit:
› Disconnect the HF connection to ground.
› The (HV) power cable of the measuring equipment must be
connected to the primary terminal (A/H1) or the higher flange.
› The measurement cable must be connected to the high
frequency terminal (HF).
1
3
TERMINAL A/H1
10 kV
Cn / FP GST-GND
AF / HF
TERMINAL A/H1
10 kV
C1 / FP GST-GND
TANQUE
2 kV
AF / HF
TANQUE
C2 / FP GST-GND
›Fig. 1a ›Fig. 1b
›Fig. 2 ›Fig. 4›Fig. 3
High Voltage Terminal
High Voltage Capacitance
Intermediate Capacitance
Electromagnetic unit
Carrier
accessories
(if included
with unit)
Grounding
Switch
(if included
with unit)
C1
1
C2
2
3

8
User manual - Annex III
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
The measurement of the insulation resistance is done to check
the integrity of the transformer insulation and to ensure that it
has not been internally damaged during transportation.
This test depends largely on the design of the transformer, the
general configuration of the test, the instruments used, etc.
The values obtained may not be representative of the actual
state of the insulation.
If this test is performed, it is recommended to contact the
manufacturer.
For field tests, the use of the megohmmeter (Megger) is very
common, and the tests that are usually done are:
› Neutral against secondary and ground.
› Each secondary against ground.
› Among the secondaries.
In the case of new equipment, the value obtained does not
provide any information, unless a short circuit is detected.
Generally, values above 200 MΩshould be expected. However,
the comparison of long-term values - such as in the case of
tanδ, or of power factor - can help determine if a device is still in good
working conditions.
Do not test at voltages above 3 kV AC or 1 kV DC.
Do not test for more than one minute. It is not recommended
to repeat this test often as the internal insulation could be
damaged.
INSULATION RESISTANCE MEASUREMENT
CAPACITIVE VOLTAGE TRANSFORMERS/
Neutral against Secondaries + Ground N/S+G
› The line cable of the measuring equipment must be connected
to the terminal N/H2* disconnecting the grounding link of the
primary winding.
› The ground cable of the measuring instrument must be
connected to the short-circuited secondary terminals together
with the ground terminals on the secondary terminal block as
well as the tank.
Secondaries against Ground S/G
› Primary terminal A/H1 must be disconnected and the neutral
connection of the (N/H2*) primary winding must be grounded.
› The line cable of the measuring equipment must be connected
to the short-circuited secondary terminals.
› The grounding cable of the measuring equipment must be
connected to the tank.
Between secondaries S/S
› This test is only applicable to transformers having more than
1 secondary.
› Primary terminal A/H1 must be disconnected and the neutral
connection of the (N/H2*) primary winding must be grounded.
› The secondaries to be assessed will be connected; one to
the line cable and the other(s) to the ground cable of the
measuring equipment.
› The test is repeated with each secondary.
* The N or H2 terminal can be located inside the secondary terminal box on the side of the box.

9
User manual - Annex III
High Voltage Instrument Transformers | DDB/DFK/DDN/DFN
The Portable Transformer Ratio Meter (TTR) is commonly used
to measure the ratio, excitation current and polarity of windings.
The values obtained are a reference that the transformer is
in good condition and can be energized. They should not be
compared with the results of factory tests carried out in the
manufacturing plant laboratory.
Due to the high precision required for this measurement, the
actual uncertainty of the test must be taken into account when
testing on site.
The TTR contains 4 terminals (this configuration may vary
depending on the manufacturer):
› H1: Black excitation terminal.
› H2: Red excitation terminal.
› X1: Black secondary terminal.
› X2: Red secondary terminal.
TRANSFORMER RATIO TEST
This test verifies the transformer ratio and polarity, and displays
a “+” signal if correct, and a “-” signal if inverted. To carry out the
test, proceed as follows (fig. 5.
› The excitation terminals (clamps marked “H”) will be connected
to the transformer’s primary circuit:
• H1 will be connected to the primary terminal of equipment A/H1.
• H2 will be connected to the ground terminal, located at the
base of the equipment.
› The clamps marked “X” will be connected to the transformer’s
secondary terminals:
• X1 will be connected to the beginning of the winding. When
the secondary has taps, you must connect X1 to the tap of the
secondary terminal which is to be tested.
• X2 will be connected at the end of the secondary winding.
• This test must be applied to each secondary separately;
in case the transformer has more than one secondary, the
secondaries which are not to be tested must be left open.
CAPACITIVE VOLTAGE TRANSFORMERS/
A/H1
H1
H2
X2
X1
a1 a2 a3
T.T.R.
n
›Fig. 5

User manual
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MU_HV_DDB_DFK_DDN_DFN_EN
V: A0 09/04/2021