IEC 60076-22-6:2021

Power transformers - Part 22-6: Power transformer and reactor fittings - Electric fans for transformers

IEC 60076-22-6:2021 covers the electric fans used in the cooling circuits of power transformers and reactors. It applies to electric fans mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to all the equipment.
The electric fans concerned by this document are of the axially operating type and are for use on liquid to air coolers and for blowing out radiators.
This document also outlines the operation requirements specific to each equipment as well as the preferred dimensions relevant for interchangeability and uniform fan assembly and the type and routine tests to be performed.

Transformateurs de puissance - Partie 22-6: Accessoires pour transformateurs de puissance et bobines d'inductance - Ventilateurs électriques pour transformateurs

L’IEC 60076-22-6:2021 couvre les ventilateurs électriques utilisés dans les circuits de refroidissement des transformateurs de puissance et des bobines d’inductance. Elle s’applique aux ventilateurs électriques montés sur des transformateurs de puissance immergés dans un liquide conformes à l'IEC 60076-1 et des bobines d’inductance conformes à l’IEC 60076­6 avec et sans conservateur pour des installations intérieures ou extérieures. Elle définit les conditions de service et les exigences mécaniques et électriques communes à tous ces équipements.
Les ventilateurs électriques concernés par le présent document sont de type à fonctionnement axial et sont destinés à être utilisés sur des aéroréfrigérants et pour souffler sur des radiateurs.
Le présent document donne également les exigences de fonctionnement spécifiques à chaque équipement ainsi que les dimensions préférentielles pertinentes pour l’interchangeabilité et l'assemblage uniforme du ventilateur, avec également les essais de type et individuels de série à réaliser.

General Information

• Status: Published
• Publication Date: 17-Jan-2021
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: TC 14 - Power transformers
• Drafting Committee: WG 32 - TC 14/WG 32
• Current Stage: PPUB - Publication issued
• Start Date: 18-Jan-2021
• Completion Date: 25-Jan-2021

Overview

IEC 60076-22-6:2021 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies requirements for electric fans used in the cooling circuits of power transformers and reactors. This standard applies specifically to axially operating electric fans installed on liquid-immersed power transformers and reactors-whether equipped with or without a conservator-intended for both indoor and outdoor applications. It defines the mechanical, electrical, and operational characteristics essential for consistent performance, interchangeability, and reliability in transformer cooling systems.

The standard ensures that electric fans effectively aid liquid to air cooling and radiator air blowing, supporting the thermal management necessary for optimal transformer and reactor operation as referenced in IEC 60076-1 and IEC 60076-6.

Key Topics

Scope and Applicability

• Covers electric fans mounted on liquid immersed transformers and reactors
• Designed for indoor/outdoor installation
• Focus on axially operating fans for liquid to air coolers and radiators

Performance and Technical Requirements

• Specifies mechanical and electrical design parameters for uniformity
• Establishes service conditions aligned with IEC 60076-1 normal operation guidelines
• Details vibration limits, corrosion protection, and degree of protection (IP codes) for electrical components like connection boxes
• Defines rated values for power and noise levels consistent with ambient conditions

Dimensions and Interchangeability

• Outlines preferred fan dimensions to facilitate interchangeability and simplified assembly
• Ensures compatibility with existing transformer and reactor fittings

Testing and Compliance

• Describes type tests and routine tests essential to verify fan performance and safety
• Includes tests for vibration, electrical endurance, and mechanical robustness
• Mandates conformity to international corrosion and electrical safety standards

Normative References

• Includes key references such as IEC 60076-1 (general power transformer requirements), IEC 60034-1 (motor ratings), ISO standards on fan performance, vibration, and corrosion testing

Applications

IEC 60076-22-6:2021 is critical for manufacturers, suppliers, and users of power transformers and reactors who require standardized, reliable, and efficient cooling fans. Applications include:

• Power Generation and Distribution: Ensures efficient heat dissipation in transformers used in power plants and substations.
• Industrial Electrical Equipment: Maintains safe operating temperatures of reactors and transformers in industrial applications.
• Transformer Maintenance and Upgrades: Facilitates replacement fan selection with consistent dimensions and performance.
• Design and Engineering: Supports engineering teams in specifying the correct cooling fans that meet international performance and safety criteria.

Adhering to this IEC standard helps reduce downtime caused by transformer overheating and ensures compliance with global operational and environmental conditions, enhancing system longevity and safety.

Related Standards

• IEC 60076-1:2011 – Power transformers – General requirements and service conditions
• IEC 60076-6 – Reactors
• IEC 60034-1 – Ratings and performance of rotating electrical machines (motors for fan drives)
• IEC 60076-10 – Determination of sound levels for power transformers
• IEC 60529 – Degrees of protection provided by enclosures (IP Code)
• ISO 5801:2017 – Fans – Performance testing using standardized airways
• ISO 9227 – Corrosion tests in artificial atmospheres (salt spray tests)
• ISO 14694 – Industrial fans – Specifications for vibration levels and balance quality

Conclusion

IEC 60076-22-6:2021 provides comprehensive guidelines crucial for the design, testing, and application of electric fans dedicated to transformer and reactor cooling. It ensures safety, quality, and efficiency by harmonizing fan details across the industry, facilitating both reliable performance and multinational interoperability in power equipment cooling solutions. This standard is indispensable for stakeholders seeking to optimize electrical equipment cooling and maintain operational excellence in line with global electrotechnical standards.

Standards Content (Sample)

IEC 60076-22-6 ®
Edition 1.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power transformers –
Part 22-6: Power transformer and reactor fittings – Electric fans for transformers

Transformateurs de puissance –
Partie 22-6: Accessoires pour transformateurs de puissance et bobines
d'inductance – Ventilateurs électriques pour transformateurs

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IEC 60076-22-6 ®
Edition 1.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power transformers –
Part 22-6: Power transformer and reactor fittings – Electric fans for transformers

Transformateurs de puissance –

Partie 22-6: Accessoires pour transformateurs de puissance et bobines

d'inductance – Ventilateurs électriques pour transformateurs

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.180 ISBN 978-2-8322-9252-5

– 2 – IEC 60076-22-6:2021 © IEC:2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Service conditions . 6
4.1 General . 6
4.2 Degree of protection of electrical components (IP) . 6
4.3 Corrosion protection . 6
5 General characteristics and requirements . 7
5.1 Main components and characteristics . 7
5.1.1 Nameplate and rating plates . 7
5.1.2 Motor drive . 7
5.1.3 Connection box . 8
5.1.4 Housing . 8
5.1.5 Fan wheel . 8
5.1.6 Protective grating . 8
5.1.7 Materials . 9
5.1.8 Vibration limits . 9
5.2 Supply conditions . 9
5.2.1 Transport and storage . 9
5.2.2 Installation and operation, operational performance . 9
5.2.3 Technical documentation . 9
5.3 Performance requirements . 10
5.3.1 General . 10
5.3.2 Rated values . 10
5.3.3 Ambient conditions for rated power and noise . 10
5.4 Tests . 10
5.4.1 General . 10
5.4.2 List of tests . 11
5.4.3 Routine tests . 11
5.4.4 Type tests . 11
Annex A (normative) Ordering designations . 12
A.1 Minimal ordering designations . 12
A.2 Additional specifications (if necessary) . 12
Annex B (informative) Performance of the fans – Typical fan characteristic speed
controlled curves . 13
Annex C (informative) Design examples . 14
Bibliography . 16

Figure B.1 – Performance of the fans . 13
Figure C.1 – Fan design example . 14
Figure C.2 – Fan design example with guide vane . 15

Table C.1 – Common selection of materials used in the construction . 15

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POWER TRANSFORMERS –
Part 22-6: Power transformer and reactor fittings –
Electric fans for transformers

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60076-22-6 has been prepared by IEC technical committee 14: Power transformers. It is
an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
14/1022/CDV 14/1041A/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.

– 4 – IEC 60076-22-6:2021 © IEC:2021
A list of all parts in the IEC 60076 series, published under the general title Power transformers,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
POWER TRANSFORMERS –
Part 22-6: Power transformer and reactor fittings –
Electric fans for transformers

1 Scope
This part of IEC 60076 covers the electric fans used in the cooling circuits of power transformers
and reactors. It applies to electric fans mounted on liquid immersed power transformers
according to IEC 60076-1 and reactors according to IEC 60076-6 with and without conservator
for indoor or outdoor installation. It outlines the service conditions and the mechanical and
electrical requirements that are common to all the equipment.
The electric fans concerned by this document are of the axially operating type and are for use
on liquid to air coolers and for blowing out radiators.
This document also outlines the operation requirements specific to each equipment as well as
the preferred dimensions relevant for interchangeability and uniform fan assembly and the type
and routine tests to be performed.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60034-1, Rotating electrical machines – Part 1: Rating and performance
IEC 60076-1:2011, Power transformers – Part 1: General
IEC 60076-10, Power transformers – Part 10: Determination of sound levels
IEC 60529, Degrees of protection provided by enclosures (IP Code)
ISO 281, Rolling bearings – Dynamic load ratings and rating life
ISO 5801:2017, Fans – Performance testing using standardized airways
ISO 9227, Corrosion tests in artificial atmospheres – Salt spray tests
ISO 12944 (all parts), Paints and varnishes – Corrosion protection of steel structures by
protective paint systems
ISO 13347-1, Industrial fans – Determination of fan sound power levels under standardized
laboratory conditions – Part 1: General overview
ISO 13347-3, Industrial fans – Determination of fan sound power levels under standardized
laboratory conditions – Part 3: Enveloping surface methods
ISO 13348, Industrial fans – Tolerances, methods of conversion and technical data presentation

– 6 – IEC 60076-22-6:2021 © IEC:2021
ISO 13857:2019, Safety of machinery – Safety distances to prevent hazard zones being
reached by upper and lower limbs
ISO 14694, Industrial fans – Specifications for balance quality and vibration levels
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
electric fan
fan specifically designed to blow air through the cooling system of a
transformer
Note 1 to entry: See IEC 60050-811:2017, 811-22-01 for definition of "fan".
4 Service conditions
4.1 General
The service conditions set out in IEC 60076-1:2011, 4.2 represent the normal scope of
operation of the equipment specified in this document. For any unusual service conditions which
require special consideration in the design of the equipment see IEC 60076-1:2011, 5.5.
Operation under such unusual service conditions shall be subject to agreement between the
purchaser and supplier, as they require special consideration in the design of the equipment.
4.2 Degree of protection of electrical components (IP)
The degree of protection of the connection box or terminal box and of the motor drive shall be
at least IP 54 according to IEC 60529, unless otherwise specified by the purchaser.
4.3 Corrosion protection
The materials used for the construction of the equipment or the surface treatment shall be
resistant to the insulating liquid and suitable to withstand the environmental conditions given in
4.1. Unless otherwise specified the dielectric liquid is mineral oil according to IEC 60296.
The corrosion protection shall be agreed between purchaser and manufacturer according to
ISO 12944 (all parts) or other standards as agreed with the purchaser. The responsibility to
specify the correct level of corrosion protection lies with the purchaser and is dependent on the
environment where the transformer will be located and on the durability required. Where no
level of corrosion protection is specified, the minimum shall be C4 medium.

5 General characteristics and requirements
5.1 Main components and characteristics
5.1.1 Nameplate and rating plates
5.1.1.1 General
The fan shall be identified by a nameplate and carry a rating plate for the fan and for the motor.
The plates shall be of the all-weather type and clearly visible. They can also be unified in one
plate.
5.1.1.2 Nameplate
The nameplate shall contain the following information:
• name or logo of the manufacturer;
• country and manufacturing location;
• number of this document (i.e. IEC 60076-22-6);
• device manufacturer's identification;
• manufacturer's serial number and year of manufacture.
The device manufacturer's identification shall allow identification of the device characteristics
from the mounting, operating and maintenance manual supplied by the manufacturer.
5.1.1.3 Electric fan rating plate
The electric fan rating plate shall contain the following information:
• the rating indicated for 50 Hz and/or 60 Hz operation;
• the rating data referring to free blowing conditions;
• volume flow in m /s referred to in the type test document;
−1
• rotational speed in min ;
• input power in kW;
• maximum current consumption at rated voltage given in A;
• a direction arrow indicating the air flow direction (in connection with the rotational direction)
either attached to the rating plate or mounted in its immediate vicinity.
All values shall be indicated for the fan without gratings.
5.1.1.4 Specifications for the motor rating plate
The motor rating plate shall be according to IEC 60034-1.
5.1.2 Motor drive
To drive the fan wheel any type of electric motor may be used, for instance three-phase
AC motors or EC motors.
The electric motor shall comply with IEC 60034-1 and be suitable for unprotected outdoor
installation.
Thermal class 155 as per IEC 60034-1 applies to all motors.

– 8 – IEC 60076-22-6:2021 © IEC:2021
Condensation water and any other intrusive water shall be able to run off without any damaging
effect. This applies to both horizontal and vertical mounting of the fan (blowing upwards).
The lifetime of the bearings of the motor shall be in accordance with ISO 281 at standard
conditions; when ball bearings are used, they shall be of standard design with lifetime exceeding
L10 30 000 h. Extreme conditions such as high temperatures, vibrations, and frequent starts
and stops can reduce the bearing lifetime considerably.
5.1.3 Connection box
The electrical connection to the power supply shall be accomplished by a connection box on
the motor drive or by a connection box at a different place, for example, at the fan housing. The
cables to the connecting box shall be suitably fixed.
The connection box provides a terminal board with clamps or similar connection facilities.
This is also applicable in the case of control systems.
The connection box shall be easily accessible and shall have a minimum of two cable entries
with metric thread.
2 2
Terminals, including the earthing terminal, shall be suitable to connect 1,5 mm , 2,5 mm ,
2 2
4,0 mm or 6,0 mm cables according to the electric power to be connected. All terminals shall
be easily accessible.
Captive screws shall be used for the cover of the connection box.
The cover seal shall be designed to prevent overpressing or slipping at all times.
5.1.4 Housing
The housing is the structure surrounding a fan, which forms the outer boundary of the coolant
gas passing through the fan.
The purpose of the housing is to duct the airflow in a specific direction.
The motor with fan wheel is mounted on the housing. The housing shall also include fixing
points to fit the fan unit to the radiator or to the cooling unit, and fixing points for the protective
grating.
The direction of air flow and rotational direction shall be indelibly marked on the housing or be
combined with the nameplate.
5.1.5 Fan wheel
The fan wheel can be mounted rigidly on the motor shaft. It can also be an integrated part of
the motor drive.
The fan wheel shall be designed in such a way that no water is able to gather, for example
leading to unbalancing. This applies to both horizontal and vertical mounting of the fan (blowing
upwards).
5.1.6 Protective grating
The protective grating is provided to prevent accidental contact with the fan wheel as well as
the access of large foreign bodies.

Fans for radiator cooling systems shall be fitted with two protective gratings (on inlet and
discharge side), fans for liquid-to-air coolers shall be fitted with one protective grating on the
accessible side. The protective gratings shall provide protection as per ISO 13857:2019,
Table 4.
5.1.7 Materials
The materials shall be chosen according to the specific environmental conditions of the
application, which shall be specified by the purchaser. Table C.1 shows a common selection of
the materials used in the construction of the fans.
5.1.8 Vibration limits
The vibration severity determined at the outer perimeter of the fan housing shall be in
accordance with ISO 14694 (BV-3).
5.2 Supply conditions
5.2.1 Transport and storage
Electric fans shall be dispatched in assembled condition ready for mounting and in such a way
that no damage can occur.
The packaging shall be suitable for indoor storage; if outdoor storage is required, this shall be
specified by the purchaser.
The instructions of the supplier concerning transport and storage shall be followed.
5.2.2 Installation and operation, operational performance
All of the fan properties given in this document are related to normed conditions. Mounting and
installation conditions affect the operational properties of the fan.
Tolerances of fan performance values shall be according to ISO 13348.
The operational conditions shall be defined using IEC 60076-1 (ambient temperature range:
−25 °C to +40 °C).
If other ambient temperatures apply, they shall be specified in the order.
5.2.3 Technical documentation
Minimum documentation to be supplied with the fan is:
• manual;
• outline drawing;
• data sheet with characteristic curve;
• conformity to the related standard.
These requirements are for the electric fan, not for the fan alone.
If requested, other documentation shall be specified in the order.

– 10 – IEC 60076-22-6:2021 © IEC:2021
5.3 Performance requirements
5.3.1 General
In 5.3.2, all rated values are with reference to fans without gratings. Depending on the mounting
situation, the supplier shall provide specific values.
In Annex A the minimum designation for ordering is indicated, in Annex B a typical example of
performance curves is shown (see Figure B.1) and in Annex C design examples are reported
(see Figure C.1 and Figure C.2).
5.3.2 Rated values
The following designations apply, conforming to ISO 5801:
• f [Hz] = frequency;
• U [V] = rated voltage;
N
• I [A] = operating current during free blowing;
• I [A] = rated current of the motor;
N
• P or P [W] = motor input power during free blowing;
e ed
• η or η [%] = static overall efficiency of the fan;
es eds
−1
• n [min ] = rotational speed;
• q [m /s] = volume flow of the fan during free blowing;
V1
• p [Pa] = maximum static pressure according to installation type A;
fs
• L [dB(A)] = A weighted sound power level on suction side of a fan during free
WA5
blowing;
• D [mm] = diameter of the fan wheel.
The characteristic curve shall be provided by the supplier (p = f(q )). The noise is dependent
fs V
on the working point and the installation conditions.
The value L is indicated to compare different types of fans. The complete sound power level
WA5
of the transformer shall be investigated in accordance with IEC 60076-10.
5.3.3 Ambient conditions for rated power and noise
The volume flow refers to an air density of 1,20 kg/m at a temperature of t = 20 °C and an air
pressure of 101,325 kPa (this corresponds to a site altitude below 1 000 m). These values shall
be measured at rated voltage with the associated frequency if no other operating data has been
specified in the order.
5.4 Tests
5.4.1 General
The tests shall be carried out in the conditions stated in 5.3.1.
Performance measurements (volume flow, static pressure, motor input and rotational speed)
shall be carried out in accordance with ISO 5801.
Noise measurements shall be carried out in accordance with ISO 13347-3.
Terms, quantities, and measuring instruments shall be in accordance with ISO 13347-1.

The purchaser and manufacturer may agree upon additional tests.
The sound power level of transformer is determined according to IEC 60076-10.
5.4.2 List of tests
5.4.2.1 Routine tests
The following list of tests is not in any specific order:
• Motor power input (5.4.3.1);
• Current (5.4.3.2);
• Rotational speed (5.4.3.3);
• Compliance of corrosion protection (5.4.3.4).
5.4.2.2 Type tests
The following list of tests is not in any specific order:
• Performance test according to ISO 5801, including characteristic curve, noise measurement
and fan efficiency (5.4.4.1);
• Conformance of corrosion protection to 4.3 (5.4.4.2).
5.4.3 Routine tests
5.4.3.1 Motor power input
The test consists of a running test under specific conditions to guarantee the specified
performance.
5.4.3.2 Current
While performing the motor power test of 5.4.3.1 the current is measured and shall be within
the specified values.
5.4.3.3 Rotational speed
While performing the motor power test of 5.4.3.1 the rotational speed is measured and shall be
within the specified values.
5.4.3.4 Compliance of corrosion protection
The supplier shall guarantee the specified corrosion protection by quality assurance procedures.
5.4.4 Type tests
5.4.4.1 Performance test according to ISO 5801
The test shall be performed according to ISO 5801:2017 installation type A. The resulting
characteristic curve, noise level and fan efficiency shall be recorded.
5.4.4.2 Conformance of corrosion protection in accordance with 4.3
The test shall be performed in accordance with ISO 9227 and evaluated according to ISO 12944
(all parts) or other standards as agreed with the purchaser.

– 12 – IEC 60076-22-6:2021 © IEC:2021
Annex A
(normative)
Ordering designations
A.1 Minimal ordering designations
– f [Hz] = frequency
– U [V] = rated voltage
N
– character of current 1 phase / 3 phase
– q [m /s] = volume flow of the fan at duty point
V1
– p [Pa] = static pressure at duty point
fs
– L [dB(A)] = A weighted sound power level of a fan at duty point
WA5
– D [mm] = nominal diameter of the fan
– fixing points
– protective grating with execution
– mounting (vertical or horizontal)
– air flow direction
– corrosion protection level
A.2 Additional specifications (if necessary)
– protection: IPXX
– ambient temperature range
– altitude above sea level on site
– motor protection according to IEC 60529

Annex B
(informative)
Performance of the fans – Typical fan characteristic
speed controlled curves
NOTE A change to the volume flow will result in a change to the sound power level and absorbed power.
Figure B.1 – Performance of the fans

– 14 – IEC 60076-22-6:2021 © IEC:2021
Annex C
(informative)
Design examples
Figure C.1 – Fan design example

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