IEC 60076-22-5:2021

Power transformers - Part 22-5: Power transformer and reactor fittings - Electric pumps for transformers

IEC 60076-22-5:2021 covers electric pumps used in the cooling circuits of power transformers and reactors. It applies to electric pumps 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 operation requirements for the electrical and hydraulic performance, mechanical design, routine testing and type testing. Additionally, performance and dimensions of preferred sizes of pump sets are specified in informative annexes.
The pumps covered in this document are rotodynamic pumps driven by a squirrel cage induction motor that is immersed in the insulating liquid.
Pump sets conforming to this document can be of in-line or end suction design.

Transformateurs de puissance - Partie 22-5 : Accessoires pour transformateurs de puissance et bobines d’inductance - Electropompes pour transformateurs

L’IEC 60076-22-5:2021 couvre les électropompes utilisées dans les circuits de refroidissement des transformateurs de puissance et des bobines d’inductance. Elle s’applique aux électropompes électriques montées sur des transformateurs de puissance immergés dans un liquide conformes à l'IEC 60076-1 et aux bobines d’inductance conformes à l'IEC 60076-6 avec et sans conservateur pour des installations intérieures ou extérieures.
Elle définit les exigences de fonctionnement pour les performances électriques et hydrauliques, la conception mécanique, les essais individuels de série et les essais de type. De plus, les performances et les dimensions des tailles préférentielles des groupes de pompes sont spécifiées dans les annexes informatives.
Le présent document couvre les pompes rotodynamiques entraînées par un moteur à induction à cage immergé dans le liquide isolant.
Les groupes de pompes conformes au présent document peuvent être des pompes en ligne ou à aspiration axiale.

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 60076-22-5:2021 is an international standard developed by the International Electrotechnical Commission (IEC) addressing the specifications and requirements for electric pumps used in power transformers and reactors. These pumps play a crucial role in the cooling circuits of liquid immersed power transformers and reactors, ensuring optimal thermal management and operational stability.

This standard applies specifically to rotodynamic electric pumps driven by squirrel cage induction motors immersed in insulating liquids. The pumps covered include both in-line and end suction designs and are suitable for installation in indoor and outdoor environments, with or without conservators, per IEC 60076-1 and IEC 60076-6 standards.

Key Topics

Scope and Application

• Defines requirements for electric pump sets used in power transformer and reactor cooling circuits.
• Covers pumps mounted on liquid immersed power transformers and reactors with and without conservators.
• Applies to both indoor and outdoor installations.

Technical Requirements

• Electrical Performance: Ensures motors comply with specifications for insulation, thermal rating, and mechanical robustness.
• Hydraulic Performance: Specifies testing for flow rate, pressure, and hydraulic interchangeability to maintain effective cooling.
• Mechanical Design Considerations:
  • Materials selection for corrosion resistance and mechanical integrity.
  • Enclosure and casing requirements to protect electrical components.
  • Terminal box configurations and protection ratings (IP codes).
• Testing Protocols:
  • Routine testing for quality control.
  • Type testing to verify pump performance and reliability.
  • Optional special tests as required.

Design and Performance Specifications

• Preferred sizes and dimensional details for end suction and in-line pump designs.
• Guidelines for direction of liquid flow and pump rotation.
• Standardized noise limits as per IEC 60034-9.
• Details on protection against external and internal corrosion.
• Use of insulating liquids according to IEC 60296 guidelines.

Normative References

IEC 60076-22-5 references key related standards such as:

• IEC 60034 series for rotating electrical machines.
• ISO standards for materials, hydraulic fluid contamination, and paint systems.
• IEC 60529 for enclosure protection ratings.

Applications

IEC 60076-22-5:2021 electric pumps are critical components in liquid cooling systems for:

• Mineral oil-immersed power transformers.
• Liquid-cooled reactors in electrical power systems.
• Transformers installed in diverse environments requiring reliable cooling equipment.
• Applications demanding robust hydraulic and electrical pump performance to ensure transformer longevity and safety.

These pumps support efficient heat dissipation, preventing overheating, and maintaining transformer performance under variable load conditions.

Related Standards

• IEC 60076-1: Power Transformers – Part 1: General
  Provides fundamental requirements for power transformers which complement the pump standards.

• IEC 60076-6: Power Transformers – Part 6: Reactors
  Defines requirements specific to reactors that incorporate electric pumps as per IEC 60076-22-5.

• IEC 60034 Series: Rotating Electrical Machines
  Includes essential standards on ratings, electrical insulation, noise limits, and protection classes vital for motor performance.

• IEC 60296: Mineral Insulating Oils for Electrical Equipment
  Specifies properties of insulating liquids used in power transformers and reactors, relevant to pump immersion.

• ISO 9906: Rotodynamic Pumps – Hydraulic Performance Acceptance Tests
  Details hydraulic testing procedures that the IEC 60076-22-5 standard aligns with for pump performance validation.

Conclusion

IEC 60076-22-5:2021 ensures standardized quality and performance of electric pumps for power transformer and reactor cooling systems worldwide. Compliance with this standard enhances the reliability, safety, and efficiency of transformer operations, supporting the critical infrastructure in electrical power networks. Engineers, manufacturers, and operators benefit from this comprehensive guide detailing operational requirements, testing methodologies, and design parameters for electric pump fittings in transformers.

Standards Content (Sample)

IEC 60076-22-5 ®
Edition 1.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power transformers –
Part 22-5: Power transformer and reactor fittings – Electric pumps for
transformers
Transformateurs de puissance –
Partie 22-5: Accessoires pour transformateurs de puissance et bobines
d'inductance – Électropompes pour transformateurs

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IEC 60076-22-5 ®
Edition 1.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power transformers –
Part 22-5: Power transformer and reactor fittings – Electric pumps for

transformers
Transformateurs de puissance –

Partie 22-5: Accessoires pour transformateurs de puissance et bobines

d'inductance – Électropompes pour transformateurs

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.180 ISBN 978-2-8322-9249-5

– 2 – IEC 60076-22-5:2021 © IEC 2021
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Service conditions . 7
4.1 General . 7
4.2 Degree of protection of electrical components (IP) . 8
4.3 External corrosion protection . 8
4.4 Internal corrosion protection . 8
4.5 Insulating liquid characteristics . 8
5 General characteristics and requirements . 8
5.1 Rating plate information . 8
5.2 Direction of liquid flow and rotation . 9
5.3 General mechanical requirements . 9
5.4 Casing or enclosure . 9
5.5 Terminal box . 10
5.6 Materials . 10
5.7 Preferred sizes . 10
5.8 Performance requirements . 10
5.8.1 General . 10
5.8.2 Hydraulic performance . 11
5.8.3 Hydraulic interchangeability . 11
5.8.4 Electrical performance . 12
5.8.5 Noise . 13
5.9 Tests . 13
5.9.1 General . 13
5.9.2 List of tests . 13
5.9.3 Routine tests . 13
5.9.4 Type tests . 14
5.9.5 Special tests . 15
(informative) Preferred sizes of end suction pumps . 16
(informative) Preferred sizes of in-line pumps . 18
(informative) Information required with enquiry, proposal and purchase order . 19
(informative) Example of use of hydraulic interchangeability tolerances . 20
Bibliography . 24

Figure 1 – Hydraulic interchangeability across the allowable operating range . 11
Figure 2 – Hydraulic interchangeability across an actual flow range . 12
Figure A.1 – Dimensions of end suction pumps . 16
Figure B.1 – Dimensions of in-line pumps . 18
Figure D.1 – Pressure-flow characteristics . 20
Figure D.2 – Tolerances as given in 5.8.3 applied to pump A . 21
Figure D.3 – Pressure-flow characteristic of pump B superimposed on the
characteristic of pump A . 22

Figure D.4 – Pressure-flow characteristic of pumps C and D superimposed on the
characteristic of pump A . 22
Figure D.5 – Flow ranges . 23

Table A.1 – Dimensions of preferred sizes of end suction pumps (mm) . 17
Table B.1 – Dimensions of preferred sizes of in-line pumps (mm) . 18

– 4 – IEC 60076-22-5:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POWER TRANSFORMERS –
Part 22-5: Power transformer and reactor fittings –
Electric pumps 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 60076-22-5 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
14/1021/CDV 14/1040A/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.
A list of all parts in the IEC 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.
– 6 – IEC 60076-22-5:2021 © IEC 2021
POWER TRANSFORMERS –
Part 22-5: Power transformer and reactor fittings –
Electric pumps for transformers

1 Scope
This part of IEC 60076 covers electric pumps used in the cooling circuits of power transformers
and reactors. It applies to electric pumps 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 operation requirements for the electrical and hydraulic performance, mechanical
design, routine testing and type testing. Additionally, performance and dimensions of preferred
sizes of pump sets are specified in informative annexes.
The pumps covered in this document are rotodynamic pumps driven by a squirrel cage induction
motor that is immersed in the insulating liquid.
Pump sets conforming to this document can be of in-line or end suction design.
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 60034-1:2017, Rotating electrical machines – Part 1: Rating and performance
IEC 60034-5, Rotating electrical machines – Part 5: Degrees of protection provided by the
integral design of rotating electrical machines (IP code) – Classification
IEC 60034-9, Rotating electrical machines – Part 9: Noise limits
IEC 60076-1:2011, Power transformers – Part 1: General
IEC 60076-7, Power transformers – Part 7: Loading guide for mineral-oil-immersed power
transformers
IEC 60085, Electrical insulation – Thermal evaluation and designation
IEC 60296, Fluids for electrotechnical applications – Mineral insulating oils for electrical
equipment
IEC 60529, Degrees of protection provided by enclosures (IP Code)
ISO 179-1:2010, Plastics – Determination of Charpy impact properties – Part 1: Non-
instrumented impact test
ISO 185, Grey cast irons – Classification

ISO 281, Rolling bearings – Dynamic load ratings and rating life
ISO 3522, Aluminium and aluminium alloys – Castings – Chemical composition and mechanical
properties
ISO 4406, Hydraulic fluid power – Fluids – Method for coding the level of contamination by solid
particles
ISO 7005-2, Metallic flanges – Part 2: Cast iron flanges
ISO 9906, Rotodynamic pumps – Hydraulic performance acceptance tests – Grades 1, 2 and 3
ISO 12944 (all parts), Paints and varnishes – Corrosion protection of steel structures by
protective paint systems
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 pump
component that circulates insulating liquid through the cooling system and
the transformer
Note 1 to entry: Two pump designs are considered: in-line and end suction pumps.
3.2
in-line pump
pump having the suction and delivery flanges on the same axis
Note 1 to entry: They can be of the centrifugal or propeller type; the axis of the flanges generally corresponds to
the axis of rotation of the pump rotor.
3.3
end suction pump
pump having the suction and delivery flanges on perpendicular axes
Note 1 to entry: They can be of the centrifugal type only; the axis of the suction flange corresponds to the axis of
rotation of the pump rotor.
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.

– 8 – IEC 60076-22-5:2021 © IEC 2021
4.2 Degree of protection of electrical components (IP)
The degree of protection of the connecting box or terminal box for outdoor installation shall be
at least IP 54 according to IEC 60529, unless otherwise specified by the purchaser.
4.3 External 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. 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.
4.4 Internal corrosion protection
It shall be ensured that pumps are clean and free of all foreign matter and contamination.
In consideration of the storage conditions and expected time between shipment and
commissioning, the corrosion protection on the inner side of the pump shall be agreed between
purchaser and manufacturer. If required by the purchaser, internal surfaces of cast iron shall
be finished with an oil resisting protective system.
As a minimum requirement, precautions shall be taken to prevent the ingress of moisture and
the development of internal corrosion by using blanking plates with gaskets.
4.5 Insulating liquid characteristics
If not otherwise specified, the insulating liquid is mineral oil according to IEC 60296 and the
operating temperature shall be in accordance with IEC 60076-7.
When the insulating liquid is not mineral oil then the viscosity variation, the operating
temperature and all the other operating characteristics shall be indicated by the purchaser.
5 General characteristics and requirements
5.1 Rating plate information
The rating plate shall be corrosion resistant and acid proof. It shall be visible when the pump is
assembled to the transformer and carry the following data:
• name or logo of the manufacturer;
• country and manufacturing location;
• number of this document (i.e. IEC 60076-22-5);
• manufacturer’s identification
• manufacturer’s serial number;
• year of manufacturing;
• type of protection by casing (IP code) compliant with IEC 60034-5;
• Rated flow [m /h] at 60 °C;
• rated pressure [kPa];
• CE marking or marking in accordance with any other regulation (if applicable);
• thermal class;
• electrical connection (Y / Δ);

• rated power or band of rated power;
• rated voltage or band of rated voltage;
• rated frequency;
• rated current or band of rated current;
• rated speed or band of rated speed;
• power factor cos φ;
• weight [kg] if over 30 kg.
The device manufacturer's identification shall allow identification of the device characteristics
from the mounting, operating and maintenance manual supplied by the manufacturer.
5.2 Direction of liquid flow and rotation
The direction of liquid flow and rotational direction shall be indelibly marked on the housing or
be combined with the nameplate.
5.3 General mechanical requirements
Electric pumps for insulating fluid are glandless, rotodynamic pumps driven by a squirrel cage
induction motor. Therefore, motor cooling and bearing lubrication shall be by circulation of the
liquid.
The lifetime of the bearings shall be according to ISO 281 at rated conditions. Where slide
bearings are used, the lifetime shall be at least 200 000 h. Ball bearings shall be of standard
design with a lifetime of at least 50 000 h. The expected lifetime of the pump shall not restrict
the expected lifetime of the transformer under normal service conditions.
At all times, the pumps shall be kept clean and free of contamination and humidity; this is
essential.
Pumps shall be suitable for mounting with the axis of the rotating unit either horizontal or vertical.
If other positions are going to be used, this shall be made known to the manufacturer.
Reverse rotation of the pump shall not cause damage to the pump.
On special request from the purchaser a mechanical or electrical device can be fitted, showing
the pump rotation.
The propeller pumps used to support the liquid flow for radiators' cooling performance (e.g. with
rated pressure of 50 kPa or less), shall have an impeller design which minimizes the restriction
of the liquid flow when the pump is idle.
5.4 Casing or enclosure
Casings or enclosures shall be capable of withstanding a maximum working pressure of
300 kPa under operating conditions without leakage.
Suction and delivery flanges shall conform to PN10 of ISO 7005-2 for end suction pumps and
PN6 or PN10 for in-line pumps. The flanges shall generally be suitable to support the pump in
normal operation. Where the pump design is such that additional supports are required, for

example, for high power end suction pumps, this shall be made known by the manufacturer.
It is the responsibility of the transformer or cooling circuit designer to ensure that the pump is
correctly supported.
– 10 – IEC 60076-22-5:2021 © IEC 2021
Drain and vent connections shall be provided and be suitable for the installation positions
allowed.
5.5 Terminal box
The manufacturer shall specify the allowed terminal box and cable entry positions, which are
preferably from below.
The connection box shall have at least one cable entry with metric thread.
An earth terminal shall be provided.
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.
A permanent label shall be provided inside the terminal box cover showing the connections
required for correct rotation of the pump.
5.6 Materials
The pump casing or enclosure shall be manufactured of either cast iron according to ISO 185
grade 200 minimum or aluminium alloy according to ISO 3522 Al-Si. Other suitable materials
agreed between the purchaser and manufacturer may be used.
External fasteners shall be stainless steel.
Rotating units shall be of all-metal construction to minimize the contribution to the electrostatic
charging tendency of the overall system.
The terminal box shall be made from a suitable metal or glass reinforced plastic (GRP). GRP
shall have a minimum Charpy impact resistance of 10 J/cm in accordance with ISO 179-1.
5.7 Preferred sizes
The preferred sizes of pumps given in this document represent the most usual requirements.
Performance and dimensions for these pumps are shown in Annex A for end suction pumps and
Annex B for in-line pumps.
Pumps with other rated performance and/or dimensions may be used by agreement between
purchaser and manufacturer. Such pumps shall comply with all other requirements of this
document.
5.8 Performance requirements
5.8.1 General
The rated conditions are determined by the rated pressure relief of the cooling circuit in relation
to the specified fluid properties at 60 °C.
It is the responsibility of the transformer or cooling circuit designer to design the pipework and
its pressure relief to ensure the proper operation of the pump. The area before and behind the
pump shall allow free flow. Especially the suction area shall be free of components that may
cause turbulences. A positive suction head of the pump shall be provided. In case of collectors,
their pipe diameters shall allow independent operation of the connected pumps.
Annex C defines the information required with enquiry, proposal and purchase order.

5.8.2 Hydraulic performance
Performance curves and nominal ratings for hydraulic performance shall be given for a liquid
temperature of 60 °C and with the motor being supplied at rated voltage. Performance curves
shall define the allowable operating range as specified by the pump manufacturer.
Pumps shall perform free of cavitation under operating conditions.
Cavitation can be avoided by low liquid velocities, low pressure drop before the pump inlet, free
inlet flow area, low partial gas content.
5.8.3 Hydraulic interchangeability
When replacing one pump with another, it is important that flow in the cooling circuit be not
greatly changed. This may be achieved by ensuring that the pump characteristic curves are
sufficiently similar.
For the purposes of this document, hydraulic interchangeability is achieved when, for each point
across the allowable operating range, one pump characteristic curve shows flow values within
±10 % or pressure values within ±8 % of another curve chosen as a datum (see Figure 1).

Key
X = Flow; Y = Pressure
1 +8 % Pressure
2 −8 % Pressure
3 +10 % Flow
4 −10 % Flow
5 Datum curve
6 Allowable operating range
7 Second curve shall lie within cross hatched area for whole of allowable operating range.
Figure 1 – Hydraulic interchangeability across the allowable operating range
Where, in a specific application, sufficient knowledge of the actual flow range is available, pump
characteristic curves may be defined as interchangeable if the above condition is met across
the actual flow range (see Figure 2).

– 12 – IEC 60076-22-5:2021 © IEC 2021
Annex D gives examples of the use of these hydraulic interchangeability tolerances.
It should be noted that hydraulic interchangeability does not ensure electrical or mechanical
interchangeability.
Key
X = Flow; Y = Pressure
1 +8 % Pressure
2 −8 % Pressure
3 +10 % Flow
4 −10 % Flow
5 Datum curve
6 Actual flow range
7 Second curve shall lie within cross hatched area for whole of actual flow range.
Figure 2 – Hydraulic interchangeability across an actual flow range
5.8.4 Electrical performance
5.8.4.1 Electrical supply
Pumps shall be suitable for direct-on-line starting with a supply voltage between 85 % and 110 %
of the nominal voltage and within 94 % to 102 % of nominal frequency. Additionally, the pump
shall be able to start at 85 % voltage at oil temperatures down to −20 °C and at 90 % down to
−25 °C without damaging heating.
Motors shall be capable of recovering normal operation in the event of a system disturbance
causing temporary loss of supply voltage for a period of up to three seconds followed by a
sudden restoration initially to 80 % of the rated voltage.
5.8.4.2 Insulation class and temperature rise
The stator winding insulation shall conform to IEC 60085 and shall be non-hygroscopic.
The temperature rise of the motor winding when operating in liquid at 115 °C shall not exceed
the liquid temperature by more than 15 K for class B insulation and 40 K for class F.

5.8.4.3 Starting current
The starting current at rated voltage shall not exceed seven times the rated full load current of
the motor subject to the tolerances given in IEC 60034-1, as appropriate.
5.8.5 Noise
Sound power levels shall not exceed the values given in IEC 60034-9.
5.9 Tests
5.9.1 General
It is essential that all test rigs are kept clean and free of contamination and foreign bodies. Oil
used for testing shall be filtered to Level 12 to 10 of ISO 4406.
The routine tests shall be carried out unless waived by the purchaser.
5.9.2 List of tests
5.9.2.1 Routine tests
The following list of tests is not in any specific order:
– Winding resistance measurement (cold) (5.9.3.1);
– Direction of rotation (5.9.3.2);
– Performance reference point (5.9.3.3);
– Applied voltage test (5.9.3.4);
– Oil leakage test (5.9.3.5);
– Mechanical integrity test (5.9.3.6).
5.9.2.2 Type tests
The following list of tests is not in any specific order:
– Hydraulic performance test (5.9.4.1);
– No-load test (5.9.4.2);
– Locked rotor test (5.9.4.3);
– Starting current test (5.9.4.4);
– Temperature rise test (5.9.4.5);
– Mechanical integrity test (5.9.4.6);
– Cold start test (5.9.4.7);
– Noise test (5.9.4.8).
5.9.2.3 Special tests
Any additional test agreed between purchaser and manufacturer.
5.9.3 Routine tests
5.9.3.1 Winding resistance measurement (cold)
Values of resistance at 20 °C shall be measured.

– 14 – IEC 60076-22-5:2021 © IEC 2021
5.9.3.2 Direction of rotation
It shall be demonstrated that the direction of rotation is correct when the pump is connected as
shown by the label on the terminal box cover.
When fitted, the device indicating correct rotation shall be shown to be clearly operational with
the pump running in the correct direction and in reverse.
5.9.3.3 Performance reference point
The pump shall be tested in accordance with Grade 2 of ISO 9906, except that the test liquid
shall be transformer oil at 60 °C, as specified in this document and speed measurements shall
not be required. The test shall be performed at zero oil flow condition with measurement of
pressure, absorbed power and current; the values shall be recorded.
5.9.3.4 Applied voltage test
With the fully assembled pump empty of oil, a dielectric test shall be carried out in accordance
with IEC 60034-1.
5.9.3.5 Oil leakage test
The fully assembled pump shall be subjected to a hydrostatic pressure test using transformer
oil at a minimum temperature of 60 °C. The test shall be carried out at a minimum pressure of
500 kPa (gauge) for a minimum period of 3 h.
5.9.3.6 Mechanical integrity
The pump shall be checked for free running of the rotating unit when turned by hand. When the
pump is running, a check shall be made for any unusual noise.
The manufacturer shall indicate the method of test used to ensure integrity of impeller fastening.
This test shall specifically demonstrate that no movement of the impeller relative to the shaft
will occur if the pump is accidentally started in reverse rotation.
5.9.4 Type tests
5.9.4.1 Hydraulic performance test
The pump shall be tested in accordance with Grade 2 of ISO 9906, except that the test liquid
shall be transformer oil at 60 °C, as specified in this document. Measurements of flow, speed,
efficiency, pressure difference between suction and delivery side, absorbed power, current and
cos ϕ shall be recorded at a minimum of six test points covering the flow range from zero flow
to maximum flow.
The test shall be performed at rated voltage and frequency.
5.9.4.2 No-load test
With the pump empty of liquid and at rated frequency and voltage, the current and electrical
power consumption shall be measured and recorded at rated voltage U , and at U /2, at U –
n n n
10 %, at U + 10 %, at U − 20 %, at U + 20 %.
n n n
5.9.4.3 Locked rotor test
With the rotor locked, the current and electrical power consumption shall be measured and
recorded at rated voltage U and at U /2, at U − 20 %, at U + 20 %.
n n n n
5.9.4.4 Starting current test
The starting current shall be measured at rated voltage.
This test shall be carried out in addition to or as an alternative to the test described in 5.9.4.3
if required by the purchaser.
5.9.4.5 Temperature rise test
A temperature rise test shall be carried out at nominal voltage for 1 h. During this test, the flow
and pressure shall be adjusted to the nominal values.
This test shall be immediately followed by a 1 h temperature rise test at U − 20 % and a further
n
1 h test at U + 20 %. During these tests, pressure and flow shall not be adjusted.
n
The average temperature rise of the stator winding for oil at 60 °C ± 5 K shall be determined by
the method of measurement of resistance variation, i.e. determination of the temperature rise
of the winding from the resistance increase according to IEC 60034-1.
The temperature rise shall not exceed 15 K for class B insulation or 40 K for class F insulation
according to IEC 60085.
5.9.4.6 Mechanical integrity
In addition to the tests detailed in 5.9.3.6, the pumps shall be run at 125 % of nominal speed
without oil for 2 min in accordance with IEC 60034-1.
5.9.4.7 Cold start test
The pump shall be started at minimum voltage with the liquid at minimum temperature. The
pump shall reach full running speed without overheating or any other adverse observations.
A full hydraulic test loop is not required but arrangements shall be made (orifice plates, etc.) to
simulate the system resistance corresponding to the nominal duty.
If required by the purchaser, means shall be provided (e.g. thermocouples) to monitor the
winding temperature.
Current, rotational speed, inlet oil temperature, outlet oil temperature and, if applicable, winding
temperature, shall be continuously recorded until the pump is running at nominal speed.
5.9.4.8 Noise test
Sound power level shall be determined by testing in accordance with IEC 60034-9.
5.9.5 Special tests
Additional tests may be agreed between purchaser and manufacturer.

– 16 – IEC 60076-22-5:2021 © IEC 2021
Annex A
(informative)
Preferred sizes of end suction pumps
The preferred sizes of pumps given in this document represent the most usual requirements.
Duties and dimensions for these pumps shall comply with the requirements of Annex A for end
suction pumps (see Figure A.1 and Table A.1) and Annex B for in-line pumps (see Figure B.1
and Table B.1).
Pumps with other rated duties and/or dimensions may be used by agreement between
purchaser and manufacturer. Such pumps shall comply with all other requirements of this
document.
Key
1 Terminal box
a
Inlet
b
Outlet
Figure A.1 – Dimensions of end suction pumps

Table A.1 – Dimensions of preferred sizes of end suction pumps (mm)
E F M N O
Ø DN
A B
max. max. max. max. max.
65 85 160 452 372 177 195 212
100 125 220 530 440 212 233 220
125 140 280 590 538 225 247 258
150 140 300 710 558 250 275 258

– 18 – IEC 60076-22-5:2021 © IEC 2021
Annex B
(informative)
Preferred sizes of in-line pumps

Key
a
Inlet
b
Outlet
Figure B.1 – Dimensions of in-line pumps
Table B.1 – Dimensions of preferred sizes of in-line pumps (mm)
D1 E H
Ø DN
max. max. max.
65 303 510 215
80 303 510 215
100 323 554 225
125 375 664 250
150 405 664 275
200 455 774 312
250 410 550 305
300 525 750 370
Annex C
(informative)
Information required with enquiry,
proposal and purchase order
Flow [m /h]
Differential pressure [bar]
These values shall be given for liquid at 60 °C.
Confirmation of characteristics of liquid pumped
– specific gravity
– viscosity at −20 °C
– viscosity at 60 °C
Nominal voltage [V]
Full load current [A]
Frequency [Hz]
Connection Y or Δ
The following list indicates by clause or subclause number where a decision is required by the
purchaser or agreement is required between purchaser and manufacturer:
3.2 to 3.3 in-line or end suction pump required;
4.3 external painting requirements;
4.4 finishing of internal surfaces of cast iron;
5.3 mounting arrangement if other than with the axis of the rotating unit horizontal or
vertical;
5.3 inform if a device to determine direction of rotation is not to be fitted;
5.4 flange dimension standard (PN6 or PN10) for in-line pumps;
5.5 size and type of cable gland;
5.3 materials of construction if other than those specified in Clause 5;
5.8.1 if preferred size and/or duty is required and, if so, the size designation;
5.9.2.1 confirmation of routine test requirements;
5.9.3.3 whether 1 in 10 pumps being subject to a hydraulic performance test is agreed;
5.9.3.5 inform if oil leakage test at 60 °C for 3 h is agreed;
5.9.4.4 type testing – inform if a starting current test is to be carried out;
5.9.4.7 inform if winding temperature is to be monitored;
5.9.5 special tests.
– 20 – IEC 60076-22-5:2021 © IEC 2021
Annex D
(informative)
Example of use of hydraulic interchangeability tolerances
Consider four similar size pumps where it is desired to replace pump A with one of pumps B, C
or D. The pressure-flow characteristics of the four pumps are as shown in Figure D.1.

Pump A Pump B
Pump C Pump D
Key
X = Flow; Y = Pressure;
1 Allowable operating range
Figure D.1 – Pressure-flow characteristics

Pump A
Key
X = Flow; Y = Pressure
1 Allowable operating range
Figure D.2 – Tolerances as given in 5.8.3 applied to pump A
The first step is to apply the tolerances as given in 5.8.3 to pump A (see Figure D.2).
The pressure-flow characteristic of each of the other pumps is then superimposed on the
characteristic of pump A and its tolerance range (note that the tolerance range has minimum
and maximum flow boundaries equal to those of the allowable operating range of pump A) as
shown in Figure D.3.
– 22 – IEC 60076-22-5:2021 © IEC 2021

Pump B
Key
X = Flow; Y = Pressure
1 Allowable operating range
Figure D.3 – Pressure-flow characteristic of pump B
superimposed on the characteristic of pump A
Pump B has an allowable operating range greater than pump A but is not hydraulically
interchangeable as part of its pressure-flow characteristic lies outside the tolerance band.

Pump C Pump D
Key
X = Flow; Y = Pressure
1 Allowable operating range
Figure D.4 – Pressure-flow characteristic of pumps C
and D superimposed on the characteristic of pump A
The pressure-flow characteristic of pump C lies within the tolerance band across the flow range
and its allowable operating range covers that of pump A, as shown in Figure D.4. Pump C is
deemed to be hydraulically interchangeable with pump A.

The pressure-flow characteristic of pump D also lies within the tolerance band across the flow
range but pump D is not hydraulically interchangeable since its allowable operating range does
not cover that of pump A.
If, in a specific application, the actual possible flow range is known to be bounded by the curves
as shown in Figure D.5, then the assessment is made only for that range. It can be seen that,
in the example of Figure D.5, all four pumps would be considered interchangeable (but only for
that one specific application).

Pump A Pump B
Pump C Pump D
Key
X = Flow; Y = Pressure;
1 Actual flow range
2 Allowable operating range
Figure D.5 – Flow ranges
– 24 – IEC 60076-22-5:2021 © IEC 2021
Bibliography
IEC 60076-6, Power transformers – Part 6: Reactors

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– 26 – IEC 60076-22-5:2021 © IEC 2021
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