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   Ventilation control (retrofit)  evaluated  
Traction equipment is cooled by ventilation to prevent over-heating. The energy needed for ventilation can be substantially reduced by demand-controlled operation, i.e. by controlling ventilation power according to actual cooling demand of the motor (or other traction equipment). The technology can be integrated in old stock as a refitting measure in some cases.
Technology field: Optimisation of traction technologies
close main section General information
  close sub-section Description
    Conversion losses of traction equipment of an electric traction unit show up as heat that must be removed from the system continuously to prevent over-heating. This is done by the coolers that in many locomotives are realised as mechanical ventilators. Whereas most modern stock allows for a continuous demand control of motor ventilation, in many old (and some modern) traction units ventilation is not demand-operated, or demand operation is not efficient. As a consequence, in many load situations ventilation runs at higher power than needed for cooling. These locomotives offer potential for corresponding retrofit measures. Conventional single-phase a.c. locomotives equipped with a two-speed ventilation system (ventilation offers only two operation modi: low and high) may be retrofitted with an optimised control of the utilisation of the two speeds. The device is based on a simple computer calculating a hypothetical excess temperature in the traction motors on the basis of recorded currents and a measurement device for the oil temperature in the transformer. Integration of a sensor measuring the real motor temperature is too complicated and risky. Threshold values automatically select one of the two ventilation speeds. As a result, full ventilation is used much less, leading to substantial energy savings. Corresponding retrofit measures have been realised at SBB and ÖBB. A similar measure could be realised on brake ventilation.
close main section General criteria
  close sub-section Status of development: in use
    At SBB and ÖBB retrofit programs have been realised successfully.
  Time horizon for broad application: in < 2 years
    (no details available)
  Expected technological development: basically exploited
    Devices for retrofit are a mature technology.
    Motivation:
   
  • Energy savings
  • Noise reduction of starting locomotives in stations
  Benefits (other than environmental): medium
   

Noise reduction

When leaving a station, coolers make a high contribution to train noise.

This can be substantially reduced by demand-controlled operation.

Wear

Less wear on bearings and collectors of ventilation motors and less dirt contamination of ventilation system.
  Barriers: medium
   

Psychological

Energy needed for auxiliaries is often seen as negligible and not worth optimising.
    Success factors:
   
  • Make detailed assessment of the number of locomotives eligible for this measure along with a cost/benefit analysis.
  • Measure should ideally be integrated into general retrofit measures to minimise standstill time of locomotives.
  • ÖBB offers other railway operators support to find individual retrofit solutions for existing stock and install a pilot device.
  Applicability for railway segments: low
    Type of traction:  electric - DC, electric - AC
    Type of transportation:  passenger - main lines, passenger - regional lines, passenger - suburban lines, freight
    In general, demand operation of motor ventilation is especially effective for stock used in services with a high degree of low-load operation, where full ventilation is not needed. For example, effect of demand operated ventilation is rather small in high speed traffic and very high for freight trains operating frequently at partial load (e.g. in mountainous regions). Furthermore, retrofit only makes sense for stock with sufficient residual life to pay back measure. ÖBB claims that control device is applicable to a variety of locomotives fitted with two-speed ventilation in Austria and in other countries.
    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: < 5%
  Share of newly purchased stock: not applicable
   

Retrofit measure!

SBB plans to retrofit all 273 locomotives of type Re 4/4 II and all 21 locomotives of type Re 4/4 III by 2008/09. ÖBB plans to retrofit locomotive series 1142 and 1044.
  Market potential (railways): low
    (no details available)
    Example:
    (no details available)
close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: 2 - 5%
  Energy efficiency potential throughout fleet: < 1%
   

At maximum load auxiliaries only account for a small share of the total energy consumption for traction. For this reason, the effect of demand-operated ventilation is rather small in high-speed trains.

However, if low-load operation is significant in operation scheme, not demand-operated ventilation contributes substantially to energy demand.

Figure 1 shows the relation between tractive power and the auxiliary power expressed as a percentage.

Figure 1: Relationship expressed in percentage terms between the auxiliary power and real-time tractive power using the example of a 5 MW traction unit.

vent.gif

Source: IZT, data from Slattenschek 2000

Locomotives fitted with two-speed ventilation are mostly operated at the higher ventilation speed, which in low-load operation leads to much higher energy demand for ventilation than actually needed.

For example, the Re 6/6 on the Swiss Gotthard consumes about 10% of its total energy demand for traction only for ventilation.

The annual energy savings per locomotive are given by SBB as 50-135 MWh / a. As soon as all locomotives are equipped, this may sum up to 1,7% of the entire power consumption of public transportation in Switzerland.

A similar project conducted in Russia yielded energy savings about 4-8% in freight trains (depending on train mass and track profile)
  Other environmental impacts: neutral
    (no details available)
close main section Economic criteria
  close sub-section Vehicle - fix costs: low
    At SBB the standstill time for rtetrofitting measures is one labour day per locomotive, including the final functional inspection. SBB gives a total cost for retrofit (including development, planning and installation) of approx. 6000 CHF (~ 4100 Euro).
  Vehicle - running costs: significant reduction
    Besides significant reductions in energy costs, maintenance costs are reduced due to less wear on bearings and motor commutators.
  Infrastructure - fix costs: none
    (no details available)
  Infrastructure - running costs: unchanged
    (no details available)
  Scale effects: low
    (no details available)
  Amortisation: < 1 year
    Both SBB and ÖBB claim a payback time for the retrofit of less than one year in most cases. For the case of the Re 6/6 and an energy price of 0,15 CHF/kWh (~ 10 Ct./kWh), SBB gives an amortisation of 4 months. Even for lower energy costs, maximum amortisation is around one year. Therefore the measure is interesting for old locomotives with short residual lifes as well.
no data available Application outside railway sector (this technology is railway specific)
close main section Overall rating
  close sub-section Overall potential: promising
  Time horizon: short-term
    Measure is highly cost-effective and promising for energy efficiency but only applicable to specific classes of locomotives.
References / Links:  Bänziger et al. 1995;  Mouginstein, Pokrovskij 2000;  Slattenschek 1997;  Slattenschek 2000
Attachments:
Related projects:  Optimised Ventilation Control Re 4/4 II, Re 4/4 III
Contact persons:
 date created: 2002-10-09
 
© UIC - International Union of Railways 2003