Kontaktledning/Sugetransformator


1 SCOPE AND PURPOSE

These specifications apply to the production and delivery of booster transformers to Norwegian National Railway Administration (NNRA).
Section 3 in this specification is informative and provides an introduction to the booster transformers function.
Section 4 is the technical requirements for the booster transformer.
Section 5 contains a detailed list of normative standards referred to by this specification.
Section 6 gives a list of the informative literature.
Section 7 is a checklist that lists all requirements contained in Section 4 where the supplier shall state whether the requirements are met, and fill in reference to the relevant documentation. If the supplier states no to any of the points, this should be justified in the comments. The comments can also be used for other comments that supplier may have.

2 FUNCTIONAL REQUIREMENTS

2.1 Purpose

The booster transformer’s main purpose is to collect most of the return current in soil and deliver to return feeders and/or rails.

2.2 Connection and interface

Booster transformers are used in overhead contact lines (OCL) with approx. 3 km. spacing. They are normally installed in kiosks on the ground or in a tunnel, but it may also be installed in outdoor environment in the OCL poles.
The primary circuit is connected in series with the contact wire. When installed in kiosks on the ground and in tunnels it shall be equipped with touch-safe feed-through connections and medium voltage insulated cables. If mounted in OCL poles the use of porcelain (or other material) feed-through connections and copper wire are used.
The secondary circuit is connected in series with the return circuit. If booster transformer are used on tracks without return feeders, the winding is connected in series with the rails (usually over filter impedances). If there is a return feeder on the track, the winding is connected via insulated wires in series with the return feeders.
On tracks that have zero-field, the midpoint of the secondary winding is connected to the nearest rail ("zero-rail"). Usually an external switch cabinet is installed in combination with the booster transformer in order to short-circuit the secondary circuit in case of failure. See also Figure 1, a) and b).

figure - figure - figure - figure

Info: In normal condition current flows in all booster transformers located between the feeding station and the trains. When a train passes a booster transformer, the pantograph momentarely shortcircuits the primary circuit. On tracks with zero field the train’s wheel-set short-circuits the secondary circuits. In all circumstances it shall be guaranteed that the train always short-circuits the secondary circuit before the primary circuit, to prevent hazardous voltages at the insulated rail joints. (NNRA will take care of this in their design of OCL and signalling system.)

3 REQUIREMENTS

In this section, the requirements for the booster transformers are defined in three main parts:

  • general requirements
  • technical requirements (including electrical, mechanical and protection requirements in relation to the environment) and
  • documentation/test regime.

If any of the requirements are very costly compared to the provider's assessment of the requirement's benefit, we request specific feedback on this in response to this specification.

3.1 General requirements

3.1.1 Quality management system

a) The supplier shall apply a quality management system that meets ISO 9001 or equivalent. A copy of the quality manual shall be submitted to the NNRA as a basis for technical approval
b) If the supplier is using a subcontractor for part-production of components, it is the supplier's responsibility to verify the supplier's quality management system. NNRA shall be allowed to visit the supplier as well as subcontractors - and if desired make random checks on the quality management system
c) The supplier shall in connection with the submission of tenders for booster transformers produce a quality plan that describes the main activities related to the manufacture, including suppliers suggested procedures for tests and expected results. The quality plan shall provide reference to specifications and standards

3.1.2 Lifespan and Maintenance

a) Lifespan: Booster Transformers shall meet all performance requirements for at least 50 years

  1. Maintenance Instructions: The supplier shall in their tender describe the maintenance necessary to make sure the lifecycle is taken care of

3.1.3 Weight and installation

a) Booster transformers that will be placed on ground level or in tunnels shall be installed in a kiosk

  1. For installation in kiosk, the weight is not essential
  2. Booster transformers in kiosks shall have safe design with no present hazardous voltages

b) No special tools for installation or connection should be necessary

  1. If special tools for installation or connection is necessary, this shall be supplied free of charge

c) If the transformer is to be installed on poles, the total weight shall not to exceed 3500 kg

  1. Booster transformers installed on poles with porcelain feed-through connections

d) Installation: On poles the booster transformer shall have mounting dimensions and holepattern as shown in Figure 2. For installation in kiosks the mounting dimensions shall be customized to the mounting rails in the kiosk
e) Both the booster transformer and the kiosk shall be constructed with lifting eye bolts or similar for crane lifting

- figur - figur - figur

3.1.4 Labeling

a) The booster transformers terminals shall be labelled with “A” and “B” on the primary circuit and with “a”, “0” and “b” on the secondary circuit. See the Figure 3
b) A rating plate shall show: current and performance, manufacturer, year of manufacture and serial number, oil type and quantity, weight with oil and weight without oil

- figur - figur - figur

3.1.5 Transformer kiosk

a) The booster transformer shall be delivered with a transformer kiosk. The type shall be clarified by actual order:

  1. The transformer kiosk shall be performed with all non-flammable materials
  2. The transformer kiosk to be delivered to tunnels, shall have doors / hatches for easy access from at least 3 sides
  3. The transformer kiosk in tunnels shall have switch cabinet on the outside of the kiosk wall

b) The tender shall include a technical description that documents:

  1. Protection category (IP classes, EN 60529)
  2. Cooling
  3. Oil spill collection
  4. Frost resistant foundation
  5. Cable Routing
  6. Solution for safe design (hazardous voltages etc.)

3.1.6 Switch cabinet

a) The booster transformer shall be delivered with a low voltage switch cabinet with circuit breaker that can short-circuit “a”, “0” and “b” terminals. Type of components to be suggested by supplier and clarified by the order
b) The tender shall include a technical description that documents:

  1. Documents and drawings for circuit breaker
  2. Protection category (IP classes, EN 60529)
  3. Cooling

3.1.7 Storage and transport

a) The booster transformers shall be delivered on pallets, suitable for handling by a forklift

3.2 Electrical requirements

3.2.1 Voltage

a) The booster transformer is termed with voltages as shown in Figure 4
b) Turnover ratio between primary (A-B) and secondary (a-b) circuits shall be 1:1
c) Nominal voltage levels for the primary circuit is 15 kV above earth potential

  1. Maximum continuous voltage is 17.25 kV, and minimum voltage is 12.0 kV. Refer to EN 50163 [18]

d) Secondary circuit will normally be under a variable voltage at maximum ± 1000 V. The voltage that occurs, shall be evenly distributed on the “a-0” and “b-0” (except for brief instances when trains are passing by)

  1. Tolerance requirements for the secondary winding: Ua0 = -Ub0 ± 0.1%

e) Booster transformers shall be used for the frequency of 16.7 Hz AC, single-phase

figur - figur - figur

3.2.2 Performance and current

When installed on new facilities or replacements NNRA uses two different types of transformers; 55kVA/600A and 95kVA/800A. The actual type will be specified when ordering.
a) Amperage requirements depending on duration are given in Table 1. The specified currents relates to the primary circuit
b) Maximum temperature increase of the oil: 60 °C
c) Test: Run the booster transformer with nominal current until stable temperature is established. Thereafter, the transformers shall be able to run for 2 hours with respectively 800 A and 1000 A, without exceeding the temperature limits
d) Maximum temperature increase of the copper coils: 65 °C
e) The short-term currents (duration less than 2 hours) shall not cause the temperature increase of more than 50 °C. (assuming that the short-term currents do not occur more frequently than at 60 minute intervals)
f) For amperages corresponding 1-minute value shall the difference between primary and secondary effective current not exceed 4%
g) Because of the relatively frequent short circuits in the OCL system the transformer shall withstand dimensioning short-circuit current of up to 1 second
h) The test protocol shall state the measured current and the terminal voltage of the secondary circuit of each of these currents at a power factor of 0.6 (inductive)

  1. Measurements shall be made at nominal frequency, i.e. 16.7 Hz

Tabell 1: Amperage requirements depending on duration
duration SN = 55 kVA
IN = 600 A
SN = 95 kVA
IN = 800 A
Continuous 600 A 800 A
2 hours 800 A 1000 A
30 minutes 950 A 1200 A
5 minutes 1600 A 2000 A
1 minute 3500 A 4000 A
1 second 20000 A 20000 A

3.2.3 Impedance (Requirements for short-circuit voltage, eZ)

Requirements to impedance specified as requirements for short-circuit voltage, eZ, i.e. the voltage applied to the circuit to provide the rated current in the windings
a) Short-circuit voltage shall not exceed the limits shown in Table 2
b) Short-circuit impedance Zk, reactance Rk and the inductance Xk is calculated according to formula 2, and documented in the test protocol

Tabell 2: Requirements for short-circuit voltage ez
SN = 55 kVA
IN = 600 A
SN = 95 kVA
IN = 800 A
ez ≤ 0.23 · UN ez ≤ 0.18 · UN

The nominal voltage (UN) is defined as shown in Formula 1:

[math]U_N = \frac{S_N}{I_N}[/math] Formula 1
[math]Z_k = \frac{e_z}{I_N}[/math] [math]R_k = \frac{P_L}{I_N^2}[/math] [math]X_k = \sqrt{Z_k^2 - R_k^2}[/math] Formula 2

3.2.4 Power loss

a) The supplier shall state the load losses (PL) at different current values specified in Table 1
b) The supplier shall also state the no-load losses
c) The tests for the load losses and no-load losses shall be performed at the nominal frequency, i.e. 16.7 Hz

3.2.5 Insulation withstand

a) Insulated feed-through connections for the primary circuit (effective value): At least 36 kV, continuous
b) Insulated feed-through connections for the secondary circuit (effective value): At least 2 kV, continuous
c) Insulation between copper coils and other parts of the transformer (effective value): at least 36 kV, continuous
d) Operating frequent withstand voltage (effective value): At least 70 kV
e) Impulse withstand voltage (referenced to a surge of 1.2 / 50 μs) for the high voltage winding: At least 170 kV. During testing, the booster transformer shall be connected in the following way:

  1. The primary windings shall be connected in series with a wave impedance, see Figure 5a
  2. Wave impedance Zb shall be between 390-470 Ω

f) Impulse withstand voltage for the low voltage (referenced to a surge of 1.2 / 50 μs): At least 20 kV

  1. Terminals that are not applied impulse voltage during testing shall be earthed, except the terminal of zero point. See Figure 5b

g)There shall be used insulated feed-through connections that satisfy EN 60137 [1]

figur - figur - figur

3.2.6 The saturation limit

a) The transformer shall not saturate at currents up to 1-minute-value (see Table 1). The secondary current shall be greater than or equal to 96 % of the primary current

  1. Upon submission of tenders, there shall be included a description of how this requirement will be tested / documented

3.2.7 Electromagnetic compatibility (EMC)

a) Requirements in EN 50121 shall be fulfilled
b) Electromagnetic immunity: Booster transformer shall have immunity against industrial environment, specified in EN 61000-6-2 [2]
c) Electromagnetic radiation: Booster transformer shall not have stronger radiation than what is accepted for domestic environment, specified in EN 61000-6-3 [3]

3.3 Mechanical and environmental engineering requirements

3.3.1 Insulation and cooling

a) Insulated booster transformer using ester or mineral oil:

  1. Booster transformers installed on OCL poles shall be insulated with synthetic ester oil with a high viscosity
  2. Booster transformers installed in a kiosk in outdoor environment according to 4.1.6 may be insulated with mineral oil or ester oil
  3. Booster transformers installed in a kiosk in tunnels according to 3.1.6 shall be insulated with ester oil which has a higher flashpoint than mineral oil

b) Dry insulated booster transformers shall be clearly marked "Not for outdoor installation" due to limited climatic protection. For installation in kiosk:

  1. Dry insulated transformers installed in a kiosk in outdoor environment according to 4.1.6
  2. Dry insulated transformers installed in a kiosk in tunnels according to 3.1.6

3.3.2 Materials

a) In the booster transformer tank there shall be a material quality (sealed steel) that provides a good adhesion on the prescribed zinc coating

  1. Steel components shall be hot-dip galvanized and tested in accordance with EN ISO 1461 [4]

b) The booster transformers coils shall consist of copper
c) For oil insulated booster transformers the oil quality shall be according to NEK 240-1 [6], class II A, modified

  1. Booster transformers shall be supplied with an oil spill collector in accordance with environmental demands
  2. Oil insulated booster transformers shall have a hermetically sealed design, and be without expansion tank

3.3.3 Protection earth

a) The booster transformer shall, at the container foot, have corrosion protected grounding screw adapted for 50/70/95 mm2 cable lugs

3.3.4 Surroundings / environment

a) Ambient temperature: -40°C to +50°C
b) Corrosion: The booster transformer surfaces and all associated external parts shall be made of corrosion resistant materials
c) Humidity: The booster transformer should be able to satisfy all functional requirements at 100% humidity
d) Dust: The booster transformer shall satisfy all the functional requirements of contaminant class III, which are defined in IEC 60815 [7]
e) Snow and ice: Requirements for snow and ice load are found in NS-EN 1991-1-3:2003
f) Vibration: The equipment shall have an appropriate design so that vibration damage does not occur, and shall be tested in accordance with IEC 600 68-2-6 [8]
g) Damage to the environment: The booster transformer shall in normal operation not leak oil, even during prolonged use, i.e. at least 40 years
h) Recycling and Disposal: Supplier shall provide information in the offer if there are hazardous materials / substances in the products, and if so, how these should be handled, both during use and disposal of the products

3.4 Documentation

In addition to the requirements in this section, pertains NS 5820 as well, "Documentation of supplier deliveries" [9].

3.4.1 Format and language

a) All documentation shall be submitted in both printed and electronic format

  1. Approved electronic formats are: open formats for text and spread sheets, *.pdf, *.dwg, *.dxf and *.dwf

b) All documentation shall be submitted in English or Norwegian

  1. Maintenance and operating documentation shall be in Norwegian

3.4.2 Documentation requirements for a tender, type testing and routine testing

a) Tender documentation shall include:

  1. The completed checklist, refer to section 6
  2. The completed list of delivery scope, refer to Appendix 1
  3. Quality management system, refer to section 3.1.1
  4. Description of methods for carrying out type tests (see Table 3 column T)
  5. Description of methods for carrying out routine tests (see Table 3 column R)
  6. Suggestions for maintenance instructions, refer to section 3.1.3
  7. Suggestions for installation instructions
  8. Plan for handling any hazardous materials, refer to section 3.3.4
  9. Technical description of the oil spill collection
  10. Technical description of the transformer kiosk, refer to Section 3.1.6
  11. Technical description of the switch cabinets, refer to Section 3.1.7
  12. Technical description of the type and coupling arrangement for overvoltage protection

b) Upon delivery of new or modified type of booster transformer, the following documentation shall be submitted:

  1. The completed checklist, refer to Section 6
  2. Reports of type tests mentioned in Table 3, including a description of the implementation, connection, results (including graphs) and any deviation
  3. All documentation which is also required in requirements c) below

c) Documentation to be supplied with each transformer:
Booster transformer shall be supplied with drawings / data sheet showing the structure, including details of materials, dimensions, dimensioned sketch and any tolerances

  1. Test protocol of routine tests listed in Table 3
  2. Maintenance schedule / manual, refer to section 3.1.3
  3. Assembly instructions
  4. Technical description of the oil spill collection
  5. Technical description of the transformer kiosk, refer to Section 3.1.6
  6. Technical description of the switch cabinets, refer to Section 3.1.7
  7. Technical description of the type and coupling arrangement for overvoltage protection

Legend to Table 3
Test categories are divided into:

  • Routine tests (R): To be performed on each transformer
  • Type or design tests (T): To be performed on a transformer that is representative of several transformers of the same type (identical construction and identical mark values)
  • Special or other tests (S): Can be both routine and type test and shall be performed if required by the customer

Ref standard Description Tab
R T S
EN 60076‐1 [10] Coil resistance X
EN 60076‐1 [10] Ratio, polarity X
EN 60076‐1 [10]
EN 60076‐8 [15]
Impedance and loss X
EN 60076‐1 [10]
EN 60076‐8 [15]
No load losses and magnetizing current X
EN 60076‐3 [12] Insulation Testing: With separate voltage source X
EN 60076‐3 [12] Insulation Testing: Induced voltage X X
EN 60076‐1 [10] Measurement of Insulation Resistance X
EN 60076‐3 [12] Partial discharges X X
EN 60076‐3 [12]
EN 60076‐4 [13]
Insulation Testing: Rated lightning impulse and switching impulse X X
EN 60076‐2 [11]
IEC 60354 [17]
Temperature Increase X
EN60076‐5 [14] Short‐circuit Test X
EN60076‐10 [16] Noise level Measurements (acoustic): X X
EN 61000‐6‐3 [3] Testing of electromagnetic radiation X X
EN 61000‐6‐2 [2] Testing of electromagnetic immunity X X
The saturation characteristics X X

4 REFERENCE DOCUMENTS

Ref
Document type, title, published by
1 EN 60137
Insulated Bushings For Alternating Voltages Above 1000 V
2 EN 61000‐6‐2
Electromagnetic compatibility (emc) ‐ Generic standards ‐ Immunity for industrial environments
3 EN 61000‐6‐3
Electromagnetic compatibility (emc) ‐ Part 6‐3: Generic standards ‐ Emission standard for residential, commercial and light‐industrial environments
4 NS‐EN ISO 1461:
Varmforsinkede belegg på fabrikkerte jern‐ og stålprodukter ‐ Spesifikasjoner og prøvingsmetoder
5 NS 1184
Metallplettering ‐ Prøvning av sinkbeleggs jevnhet ved kobbersulfatmetoden
6 NEK 240‐1:2008
Isoleroljer ‐ Kvalitative krav, overvåkning og vedlikehold ‐ Del 1: Transformatorer og brytere med tilhørende oljefylt utstyr
7 IEC 60815
Guide for the selection of insulators in respect of polluted conditions
8 IEC 60068‐2‐6
Environmental Testing ‐ Test Fc And Guidance: Vibration (Sinusoidal)
9 NS 5820
Dokumentasjon av utstyrsleveranser
10 EN 60076‐1
Power Transformers ‐ Part 1: General
11 EN 60076‐2
Power Transformers ‐ Temperature Rise
12 EN 60076‐3
Power Transformers ‐ Part 3: Insulation Levels, Dielectric Tests And External Clearances In AIR
13 EN 60076‐4
Power Transformers ‐ Part 4: Guide To The Lightning Impulse And Switching Impulse Testing ‐ Power Transformers And Reactors
14 EN 60076‐5
Power Transformers ‐ Ability To Withstand Short Circuit
15 IEC 60076‐8
Power Transformers – Application Guide
16 EN 60076‐10
Power Transformers ‐ Part 10: Determination Of Sound Levels
17 IEC 60354
Loading guide for oil‐immersed power transformers
18 EN 50163
Railway applications ‐ supply voltages of traction systems EN 60529, Degrees of protection provided by enclosures (IP code)(IEC 60529)

5 OTHER LITERATURE

NNRA Technical regulations
Common set of rules
NNRA Technical regulations
Common electrical rules – Design and building
NNRA Technical regulations
Overhead Contact Lines ‐ Design
NNRA Technical regulations
Overhead Contact Lines ‐ Building
Carlson, Fuhr, Schemel, Wegesheider:
Testing of Power Transformers
ABB , 2003
ISBN 3‐00‐010400‐3

6 CHECKLIST

The supplier shall sign out all points of the specification in the following checklist. Any deviation from these requirements shall be commented, which points a), b), c), etc., that are not met and what / why point is not fulfilled.

Description of requirement Compliant (Yes/No) Supplier’s references Supplier’s comments
3.1.1 Quality management system

a)
b)
c)
3.1.2 Lifespan and Maintenance
a)
c)
3.1.3 Weight and installation
a)
b)
c)
d)
3.1.4 Labeling
a)
b)
3.1.5 Transformer kiosk
a)
b)
3.1.6 Switch cabinet
a)
b)
3.1.7 Storage and transport
a)
3.2.2 Performance and current
a)
b)
c)
d)
e)
f)
g)
h)
3.2.3 Impedance (Requirements for short-circuit
a)
b)
3.2.4 Power loss
a)
b)
c)
3.2.5 Insulation withstand
a)
b)
c)
d)
e)
f)
g)
3.2.6 The saturation limit
a)
3.2.7 Electromagnetic compatibility (EMC)
a)
b)
c)
3.3.1 Insulation and cooling
a)
b)
3.3.2 Materials
a)
b)
c)
3.3.3 Protection earth
a)
3.3.4 Surroundings / environment
a)
b)
c)
d)
e)
f)
g)
h)
3.4.1 Format and language
a)
b)
3.4.2 Documentation requirements for a tender, type testing and routine testing
a)
b)
c)