MR VACUTAP VV Installation and operation manual

On-load tap-changer
VACUTAP® VV®
Installation and commissioning instructions
4349322/01 EN

© All rights reserved by Maschinenfabrik Reinhausen
Dissemination and reproduction of this document and use and disclosure of its content are strictly prohibited
unless expressly permitted.
Infringements will result in liability for compensation. All rights reserved in the event of the granting of patents,
utility models or designs.
The product may have been altered since this document was published.
We reserve the right to change the technical data, design and scope of supply.
Generally the information provided and agreements made when processing the individual quotations and orders
are binding.
The original operating instructions were written in German.

Table of contents
Maschinenfabrik Reinhausen GmbH 2020 34349322/01 EN VACUTAP® VV®
Table of contents
1 Introduction......................................................................................................................... 7
1.1 Manufacturer....................................................................................................................................... 7
1.2 Completeness..................................................................................................................................... 7
1.3 Safekeeping........................................................................................................................................ 7
1.4 Notation conventions .......................................................................................................................... 7
1.4.1 Hazard communication system .............................................................................................................................7
1.4.2 Information system................................................................................................................................................9
1.4.3 Instruction system .................................................................................................................................................9
2 Safety................................................................................................................................. 11
2.1 Appropriate use ................................................................................................................................ 11
2.2 Inappropriate use.............................................................................................................................. 12
2.3 Fundamental safety instructions ....................................................................................................... 12
2.4 Personal protective equipment ......................................................................................................... 14
2.5 Personnel qualification...................................................................................................................... 15
3 Product description.......................................................................................................... 16
3.1 Scope of delivery .............................................................................................................................. 16
3.2 On-load tap-changer......................................................................................................................... 16
3.2.1 Function description ............................................................................................................................................16
3.2.2 Setup/models ......................................................................................................................................................17
3.2.3 Nameplate and serial number .............................................................................................................................20
3.2.4 Protective devices ...............................................................................................................................................20
3.3 Drive shaft......................................................................................................................................... 26
3.3.1 Function description ............................................................................................................................................26
3.3.2 Design/versions...................................................................................................................................................27
4 Packaging, transport and storage .................................................................................. 32
4.1 Packaging ......................................................................................................................................... 32
4.1.1 Suitability.............................................................................................................................................................32
4.1.2 Markings..............................................................................................................................................................33
4.2 Transportation, receipt and handling of shipments........................................................................... 33
4.3 Storage of shipments........................................................................................................................ 34
4.4 Unpacking shipments and checking for transportation damages ..................................................... 35

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Maschinenfabrik Reinhausen GmbH 202044349322/01 ENVACUTAP® VV®
5 Mounting ........................................................................................................................... 36
5.1 Preparatory work .............................................................................................................................. 36
5.1.1 Fitting mounting flange on transformer cover......................................................................................................36
5.1.2 Fitting stud bolts on mounting flange ..................................................................................................................37
5.2 Installing the on-load tap-changer in the transformer (standard version) ......................................... 37
5.2.1 Fastening on-load tap-changer to transformer cover ..........................................................................................37
5.2.2 Connecting the tap winding and on-load tap-changer take-off lead....................................................................45
5.2.3 Performing transformer ratio test before drying ..................................................................................................46
5.2.4 Performing DC resistance measurement on transformer....................................................................................47
5.2.5 Drying on-load tap-changer in autoclave ............................................................................................................47
5.2.6 Drying on-load tap-changer in transformer tank..................................................................................................54
5.2.7 Filling the oil compartment of the on-load tap-changer with insulating fluid........................................................57
5.2.8 Performing transformer ratio test after drying .....................................................................................................58
5.3 Installing on-load tap-changer in transformer (bell-type tank version).............................................. 59
5.3.1 Inserting on-load tap-changer into supporting structure......................................................................................59
5.3.2 Connecting the tap winding and on-load tap-changer take-off lead....................................................................60
5.3.3 Performing transformer ratio test before drying ..................................................................................................61
5.3.4 Performing DC resistance measurement on transformer....................................................................................62
5.3.5 Drying on-load tap-changer in autoclave ............................................................................................................62
5.3.6 Lifting top part of on-load tap-changer head off supporting flange (bottom part) ................................................69
5.3.7 Attaching the bell-type tank and connecting the on-load tap-changer to the top part of the on-load tap-changer
head ....................................................................................................................................................................73
5.3.8 Drying on-load tap-changer in transformer tank..................................................................................................78
5.3.9 Filling the oil compartment of the on-load tap-changer with insulating fluid........................................................81
5.3.10 Performing transformer ratio test after drying .....................................................................................................82
5.4 Fitting protective devices and drive components.............................................................................. 83
5.4.1 Electrically connecting the temperature sensor ..................................................................................................83
5.4.2 Connecting tap-change supervisory control........................................................................................................83
5.4.3 Installing protective relay in piping and connecting.............................................................................................85
5.4.4 Installing and connecting the pressure monitoring device ..................................................................................96
5.4.5 Fitting motor-drive unit ........................................................................................................................................99
5.4.6 Fitting drive shaft.................................................................................................................................................99
5.4.7 Centering on-load tap-changer and motor-drive unit ........................................................................................153
5.4.8 Making the electrical connections for the motor-drive unit ................................................................................153

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Maschinenfabrik Reinhausen GmbH 2020 54349322/01 EN VACUTAP® VV®
6 Commissioning............................................................................................................... 154
6.1 Commissioning the on-load tap-changer at the transformer manufacturer's site ........................... 154
6.1.1 Bleeding on-load tap-changer head and suction pipe.......................................................................................154
6.1.2 Grounding the on-load tap-changer ..................................................................................................................156
6.1.3 Checking motor-drive unit .................................................................................................................................158
6.1.4 High-voltage tests on the transformer ...............................................................................................................158
6.2 Transporting transformer to the operating site................................................................................ 159
6.2.1 Transport with drive removed............................................................................................................................159
6.2.2 Transport with full transformer tank and without oil conservator.......................................................................160
6.2.3 Transport with empty transformer tank .............................................................................................................160
6.3 Commissioning transformer at operating site ................................................................................. 162
6.3.1 Filling the oil compartment of the on-load tap-changer with insulating fluid......................................................162
6.3.2 Bleeding on-load tap-changer head and suction pipe.......................................................................................163
6.3.3 Checking motor-drive unit .................................................................................................................................165
6.3.4 Checking protective relay..................................................................................................................................166
6.3.5 Checking pressure monitoring device ...............................................................................................................167
6.3.6 Commissioning the transformer ........................................................................................................................168
7 Fault elimination ............................................................................................................. 169
7.1 Tripping the protective relay and re-commissioning the transformer.............................................. 171
7.1.1 Flap valve in OPERATION position ..................................................................................................................172
7.1.2 Flap valve in OFF position ................................................................................................................................172
7.1.3 Re-commissioning the transformer ...................................................................................................................172
7.2 Tripping the pressure monitoring device and putting the transformer back into operation............. 173
7.2.1 Sensor in the OPERATION position .................................................................................................................173
7.2.2 Sensor in the OFF position ...............................................................................................................................173
7.2.3 Re-commissioning the transformer ...................................................................................................................174
8 Technical data................................................................................................................. 175
8.1 Technical data for on-load tap-changer .......................................................................................... 175
8.1.1 On-load tap-changer properties ........................................................................................................................175
8.1.2 Permissible ambient conditions.........................................................................................................................175
8.2 Technical data for protective relay.................................................................................................. 176
8.3 Special models of protective relay .................................................................................................. 178
8.3.1 Protective relay with CO change-over contact as tripping switch .....................................................................178
8.3.2 Protective relay with several dry-reed magnetic switches.................................................................................179
8.4 Technical data for pressure monitoring device ............................................................................... 179

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Maschinenfabrik Reinhausen GmbH 202064349322/01 ENVACUTAP® VV®
8.5 Limit values for dielectric strength and water content of insulating fluids ....................................... 181
9 Drawings ......................................................................................................................... 182
9.1 737774............................................................................................................................................ 183
9.2 898863............................................................................................................................................ 184
9.3 737060............................................................................................................................................ 185
9.4 738902............................................................................................................................................ 186
9.5 739172............................................................................................................................................ 187
9.6 890183............................................................................................................................................ 188
9.7 898866............................................................................................................................................ 189
9.8 899110............................................................................................................................................ 190
9.9 899409............................................................................................................................................ 191
9.10 899083............................................................................................................................................ 192
9.11 899051............................................................................................................................................ 193
9.12 733469............................................................................................................................................ 194
9.13 892916............................................................................................................................................ 195
Glossary .......................................................................................................................... 196

1 Introduction
Maschinenfabrik Reinhausen GmbH 2020 74349322/01 EN VACUTAP® VV®
1 Introduction
This technical file contains detailed descriptions of the safe and proper in-
stallation, connection, and commissioning of the product.
It also includes safety instructions and general information about the prod-
uct.
Information about operation can be found in the operating instructions.
This technical file is intended solely for specially trained and authorized per-
sonnel.
1.1 Manufacturer
The product is manufactured by:
Maschinenfabrik Reinhausen GmbH
Falkensteinstraße 8
93059 Regensburg
Tel.: [phone]
E-mail: [email protected]
Further information on the product and copies of this technical file are avail-
able from this address if required.
1.2 Completeness
This technical file is incomplete without the supporting documents.
The following documents are considered supporting documents:
▪ Unpacking instructions
▪ Supplement
▪ Routine test report
▪ Connection diagrams
▪ Dimensional drawings
▪ Order confirmation
1.3 Safekeeping
Keep this technical file and all supporting documents ready at hand and ac-
cessible for future use at all times.
1.4 Notation conventions
1.4.1 Hazard communication system
Warnings in this technical file are displayed as follows.

1 Introduction
Maschinenfabrik Reinhausen GmbH 202084349322/01 ENVACUTAP® VV®
1.4.1.1 Warning relating to section
Warnings relating to sections refer to entire chapters or sections, sub-sec-
tions or several paragraphs within this technical file. Warnings relating to
sections use the following format:
WARNING Type of danger!
Source of the danger and outcome.
► Action
► Action
1.4.1.2 Embedded warning information
Embedded warnings refer to a particular part within a section. These warn-
ings apply to smaller units of information than the warnings relating to sec-
tions. Embedded warnings use the following format:
DANGER! Instruction for avoiding a dangerous situation.
1.4.1.3 Signal words and pictograms
The following signal words are used:
Signal word Definition
DANGER Indicates a hazardous situation which, if not avoided, will result in
death or serious injury.
WARNING Indicates a hazardous situation which, if not avoided, could result
in death or serious injury.
CAUTION Indicates a hazardous situation which, if not avoided, could result
in minor or moderate injury.
NOTICE Indicates measures to be taken to prevent damage to property.
Table1: Signal words in warning notices
Pictograms warn of dangers:
Pictogram Definition
Warning of a danger point
Warning of dangerous electrical voltage

1 Introduction
Maschinenfabrik Reinhausen GmbH 2020 94349322/01 EN VACUTAP® VV®
Pictogram Definition
Warning of combustible substances
Warning of danger of tipping
Warning of danger of crushing
Table2: Pictograms used in warning notices
1.4.2 Information system
Information is designed to simplify and improve understanding of particular
procedures. In this technical file it is laid out as follows:
Important information.
1.4.3 Instruction system
This technical file contains single-step and multi-step instructions.
Single-step instructions
Instructions which consist of only a single process step are structured as fol-
lows:
Aim of action
üRequirements (optional).
► Step 1 of 1.
ðResult of step (optional).
ðResult of action (optional).
Multi-step instructions
Instructions which consist of several process steps are structured as follows:

1 Introduction
Maschinenfabrik Reinhausen GmbH 202010 4349322/01 ENVACUTAP® VV®
Aim of action
üRequirements (optional).
1. Step 1.
ðResult of step (optional).
2. Step 2.
ðResult of step (optional).
ðResult of action (optional).

2 Safety
Maschinenfabrik Reinhausen GmbH 2020 114349322/01 EN VACUTAP® VV®
2 Safety
▪ Read this technical file through to familiarize yourself with the product.
▪ This technical file is a part of the product.
▪ Read and observe the safety instructions provided in this chapter.
▪ Read and observe the warnings in this technical file in order to avoid func-
tion-related dangers.
▪ The product is manufactured on the basis of state-of-the-art technology.
Nevertheless, risks to life and limb for the user or impairment of the prod-
uct and other material assets due to the function may arise in the event of
improper use.
2.1 Appropriate use
The product is an on-load tap-changer and adjusts the transmission ratio of
transformers without interrupting the load flow. The product is designed
solely for use in electrical energy systems and facilities. If used as intended
and in compliance with the requirements and conditions specified in this
technical file as well as the warning notices in this technical file and attached
to the product, then the product does not present any danger to people,
property or the environment. This applies throughout the service life of the
product, from delivery, installation and operation to removal and disposal.
The following is considered appropriate use:
▪ Use the product only with the transformer/motor-drive unit specified in the
order.
▪ The serial numbers of on-load tap-changer and on-load tap-changer ac-
cessories (drive, drive shaft, bevel gear, protective relay, etc.) must match
if the on-load tap-changer and on-load tap-changer accessories are sup-
plied as a set for one order.
▪ You will find the standard valid for the product and the year of issue on the
nameplate.
▪ Operate the product in accordance with this provided technical file, the
agreed delivery conditions and technical data.
▪ Ensure that all necessary work is performed by qualified personnel only.
▪ Only use the equipment and special tools included in the scope of delivery
for the intended purpose and in accordance with the specifications of this
technical file.
▪ The on-load tap-changer is not intended to be used with an oil filter unit.
Permitted electrical operating conditions
In addition to the design data in accordance with the order confirmation, ob-
serve the following limits for the through-current and the step voltage:
In the standard version, the on-load tap-changer is designed for sinusoidal
50/60 Hz AC current with a curve form symmetrical to the zero axis and can
switch twice the rated through-current Ir at its rated step voltage Uir.

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Maschinenfabrik Reinhausen GmbH 202012 4349322/01 ENVACUTAP® VV®
Exceeding the rated step voltage Uir for a short period by up to 10% is per-
mitted if the rated through-current Ir is not exceeded.
2.2 Inappropriate use
Use is considered inappropriate if the product is used in a way other than as
described in the "Appropriate use" section. In addition, observe the following:
Prohibited electrical operating conditions
All operating conditions that do not comply with the design data in accor-
dance with the order confirmation are prohibited.
Prohibited operating conditions may arise due to short circuits as well as due
to inrush current impulses when energizing transformers or other electrical
machines. This applies to the affected transformer itself just as it does to
transformers electrically connected in parallel or serially or other electrical
machines.
Higher voltages may occur due to transformer overexcitation following load
shedding, for example.
Operations outside of the permitted operating conditions can lead to injury to
persons and damage to the product.
▪ Prevent any such operations outside of the permitted operating conditions
by taking suitable measures.
2.3 Fundamental safety instructions
To prevent accidents, disruptions and damage as well as unacceptable ad-
verse effects on the environment, those responsible for transport, installa-
tion, operation, maintenance and disposal of the product or parts of the prod-
uct must ensure the following:
Personal protective equipment
Loosely worn or unsuitable clothing increases the danger of becoming
trapped or caught up in rotating parts and the danger of getting caught on
protruding parts. This poses a danger to life and limb.
▪ Wear appropriate personal protective equipment such as a helmet, work
gloves, etc. for the respective activity.
▪ Never wear damaged personal protective equipment.
▪ Never wear rings, necklaces, or other jewelry.
▪ If you have long hair, wear a hairnet.

2 Safety
Maschinenfabrik Reinhausen GmbH 2020 134349322/01 EN VACUTAP® VV®
Work area
Untidy and poorly lit work areas can lead to accidents.
▪ Keep the work area clean and tidy.
▪ Make sure that the work area is well lit.
▪ Observe the applicable laws for accident prevention in the relevant coun-
try.
Working during operation
The product may only be operated in a sound, operational condition. Other-
wise it poses a danger to life and limb.
▪ Regularly check the operational reliability of safety equipment.
▪ Comply with the inspection work, maintenance work and maintenance in-
tervals described in this technical file.
Explosion protection
Highly flammable or explosive gases, vapors and dusts can cause serious
explosions and fire. This increases the danger to life and limb.
▪ Do not install, operate or perform maintenance work on the product in ar-
eas where a risk of explosion is present.
Safety markings
Warning signs and safety information plates are safety markings on the
product. They are an important aspect of the safety concept.
▪ Observe all safety markings on the product.
▪ Make sure all safety markings on the product remain intact and legible.
▪ Replace safety markings that are damaged or missing.
Ambient conditions
To ensure reliable and safe operation, the product must only be operated
under the ambient conditions specified in the technical data.
▪ Observe the specified operating conditions and requirements for the in-
stallation location.
Auxiliary materials and operating materials
Auxiliary materials and operating materials not approved by the manufac-
turer can lead to personal injury, damage to property and malfunctions of the
product.
▪ Use insulating fluids that meet the requirements in accordance with IEC
60296.
▪ If approved by the transformer manufacturer, you can use alternative insu-
lating fluids approved by Maschinenfabrik Reinhausen GmbH.

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Maschinenfabrik Reinhausen GmbH 202014 4349322/01 ENVACUTAP® VV®
▪ It is imperative that you consult with Maschinenfabrik Reinhausen GmbH
because specific operating conditions apply to alternative insulating fluids.
▪ Only use conductive and grounded hoses, pipes, and pump equipment
that are approved for flammable liquids.
▪ Only use lubricants and auxiliary materials approved by the manufacturer.
▪ Contact the manufacturer.
Modifications and conversions
Unauthorized or inappropriate changes to the product may lead to personal
injury, material damage and operational faults.
▪ Only modify the product after consultation with Maschinenfabrik Rein-
hausen GmbH.
Spare parts
Spare parts not approved by Maschinenfabrik Reinhausen GmbH may lead
to physical injury, damage to the product and malfunctions.
▪ Only use spare parts that have been approved by Maschinenfabrik Rein-
hausen GmbH.
▪ Contact Maschinenfabrik Reinhausen GmbH.
2.4 Personal protective equipment
Personal protective equipment must be worn during work to minimize risks to
health.
▪ Always wear the personal protective equipment required for the job at
hand.
▪ Never wear damaged personal protective equipment.
▪ Observe information about personal protective equipment provided in the
work area.
Protective clothing Close-fitting work clothing with a low tearing strength,
with tight sleeves and with no protruding parts. It mainly
serves to protect the wearer against being caught by
moving machine parts.
Safety shoes To protect against falling heavy objects and slipping on
slippery surfaces.
Safety glasses To protect the eyes from flying parts and splashing liq-
uids.
Visor To protect the face from flying parts and splashing liq-
uids or other dangerous substances.
Hard hat To protect against falling and flying parts and materials.
Hearing protection To protect against hearing damage.
Protective gloves To protect against mechanical, thermal, and electrical
hazards.
Table3: Personal protective equipment

2 Safety
Maschinenfabrik Reinhausen GmbH 2020 154349322/01 EN VACUTAP® VV®
2.5 Personnel qualification
The person responsible for assembly, commissioning, operation, mainte-
nance and inspection must ensure that the personnel are sufficiently quali-
fied.
Electrically skilled person
The electrically skilled person has a technical qualification and therefore has
the required knowledge and experience, and is also conversant with the ap-
plicable standards and regulations. The electrically skilled person is also pro-
ficient in the following:
▪ Can identify potential dangers independently and is able to avoid them.
▪ Is able to perform work on electrical systems.
▪ Is specially trained for the working environment in which (s)he works.
▪ Must satisfy the requirements of the applicable statutory regulations for
accident prevention.
Electrically trained persons
An electrically trained person receives instruction and guidance from an
electrically skilled person in relation to the tasks undertaken and the poten-
tial dangers in the event of inappropriate handling as well as the protective
devices and safety measures. The electrically trained person works exclu-
sively under the guidance and supervision of an electrically skilled person.
Operator
The operator uses and operates the product in line with this technical file.
The operating company provides the operator with instruction and training
on the specific tasks and the associated potential dangers arising from im-
proper handling.
Technical Service
We strongly recommend having maintenance, repairs and retrofitting carried
out by our Technical Service department. This ensures that all work is per-
formed correctly. If maintenance is not carried out by our Technical Service
department, please ensure that the personnel who carry out the mainte-
nance are trained and authorized by Maschinenfabrik Reinhausen GmbH to
carry out the work.
Authorized personnel
Authorized personnel are trained by Maschinenfabrik Reinhausen GmbH to
carry out special maintenance.

3 Product description
Maschinenfabrik Reinhausen GmbH 202016 4349322/01 ENVACUTAP® VV®
3 Product description
3.1 Scope of delivery
The product is packaged with protection against moisture and is usually de-
livered as follows:
▪ On-load tap-changer
▪ Motor-drive unit
▪ Drive shaft with coupling parts and bevel gear
▪ Protective device
▪ Technical files
Please refer to the delivery slip for full details of scope of delivery.
On-load tap-changers can also be provided as an on-load tap-changer set
with a common motor-drive unit.
Note the following information:
▪ Check the shipment for completeness on the basis of the shipping docu-
ments.
▪ Store the parts in a dry place until installation
▪ The product must remain in its airtight, protective wrapping and may only
be removed immediately before installation
You will find more information in the "Packaging, transport, and stor-
age" [►Section 4, Page 32] chapter.
3.2 On-load tap-changer
3.2.1 Function description
On-load tap-changers are used to adjust the transmission ratio of transform-
ers without interrupting the load flow. Fluctuations in voltage occurring in the
power transmission grid, for example, can therefore be compensated for. For
this purpose, on-load tap-changers are fitted in transformers and connected
to the active part of the transformer.

3 Product description
Maschinenfabrik Reinhausen GmbH 2020 174349322/01 EN VACUTAP® VV®
A motor-drive unit which receives a control impulse (e.g. from a voltage reg-
ulator) changes the operating position of the on-load tap-changer, as a result
of which the transformer's transmission ratio is adapted to the prevailing op-
erating requirements.
Figure1: System overview of on-load tap-changer transformer
1 Transformer tank 6 Gear unit
2 Motor-drive unit 7 On-load tap-changer
3 Vertical drive shaft 8 Protective relay
4 Bevel gear 9 Oil conservator
5 Horizontal drive shaft 10 Active part
3.2.2 Setup/models
The following drawing shows the main components of the on-load tap-
changer.

3 Product description
Maschinenfabrik Reinhausen GmbH 202018 4349322/01 ENVACUTAP® VV®
You will find a detailed drawing of the on-load tap-changer in the "Drawings
[►Section 9, Page 182]" section.
Figure2: On-load tap-changer
1 Upper gear unit 2 On-load tap-changer head
3 Supporting flange 4 Connection contact
5 Oil compartment 6 Change-over selector
7 Pipe bend 8 Rupture disk
3.2.2.1 Pipe connections
The on-load tap-changer head features 4 pipe connections for different pur-
poses.

3 Product description
Maschinenfabrik Reinhausen GmbH 2020 194349322/01 EN VACUTAP® VV®
Depending on the order, some or all of these pipe connections are fitted with
pipe bends ex factory. All pipe bends can be freely swiveled once the pres-
sure ring is loosened.
Figure3: Pipe connections with pipe bends
Pipe connection Q
The pipe connection Q is closed with a blank cover.
The functions of the R and Q pipe connections can be interchanged.
Pipe connection S
The pipe bend on pipe connection S features a vent screw and can be con-
nected to a pipe that ends with a drain valve on the side of the transformer
tank at operating height. If the on-load tap-changer is fitted with an oil suc-
tion pipe, the on-load tap-changer can be completely emptied via pipe con-
nection S.
Pipe connection R
Pipe connection R is intended for attachment of the protective relay and con-
nection of the on-load tap-changer oil conservator and can be interchanged
with pipe connection Q.
Pipe connection E2
Pipe connection E2 is sealed off with a blank cover. It leads into the oil tank
of the transformer, directly under the on-load tap-changer head and can be
connected to a collective pipe for the Buchholz relay, if necessary. This pipe
connection serves a further purpose, namely to equalize the pressure be-
tween the transformer tank and oil compartment of the on-load tap-changer,
which is necessary for drying, filling with insulating fluid and transportation of
the transformer.

3 Product description
Maschinenfabrik Reinhausen GmbH 202020 4349322/01 ENVACUTAP® VV®
3.2.3 Nameplate and serial number
The nameplate is on the on-load tap-changer head cover.
Figure4: Nameplate with serial number
3.2.4 Protective devices
The on-load tap-changer is equipped with the following protective devices.
3.2.4.1 Protective relay
3.2.4.1.1 Function description
The protective relay is looped into the circuit breaker tripping circuit, thus
protecting the on-load tap-changer and transformer in the event of a fault
within the on-load tap-changer oil compartment. It is tripped when the speci-
fied speed of flow from the on-load tap-changer head to the oil conservator
is exceeded due to a fault. The flowing insulating fluid actuates the flap valve
which tips over into position OFF. The contact in the dry-reed magnetic
switch is thereby actuated, the circuit breakers are tripped, and the trans-
former is de-energized.
The protective relay is a component of an on-load tap-changer filled with in-
sulating fluid and its properties conform to the respective applicable version
of IEC publication 60214-1.
Diverter switch operations at rated switching capacity or at permissible over-
load will not cause the protective relay to trip.
The protective relay responds to flow, not to gas accumulated in the protec-
tive relay. It is not necessary to bleed the protective relay when filling the
transformer with insulating fluid. Gas accumulation in the protective relay is
normal.