Power transformers that feed rail networks still consume energy when idling, especially at night when no vehicles are running on the network. Switching off one or more transformers when there is no or little load on the electrical network can bring significant energy savings. This requires a good knowledge of how the electricity network is used and sized.
There should be regular evaluations of the global sizing of the electricity network, to ensure that all equipment is necessary. When dealing with old transformers, operators must be cautious, because regular disconnections can harm the systems and reduce their lifetime.
Escalators located in public transport stations and buildings operate for around 20 hours per day and are designed to support a maximum load of up to two persons standing on each stair. However, they run most of the time with no load or very low load and therefore offer significant energy-saving potential.There are several strategies for improving the energy efficiency of escalators:
- Fitting old escalators with sensors that detect the presence of passengers
- Reducing the supplied voltage to partially loaded motors to increase their efficiency
- Installing less powerful or more efficient motors
- Defining a slow start mode in order to reduce the high load required for starting the escalator
- Keeping the escalators in slow motion, which is more energy-efficient for heavy-duty locations with many passengers and highly frequent start-stops ¾ Optimising the heating system used to avoid the escalator getting blocked when freezing. A tem- perature sensor can deactivate this feature when needed
- Training agents to detect any defective escalator.
Computer servers produce heat and must be cooled by the use of ventilation systems. As computer servers become larger and more complex, cooling of the active components has become a critical factor for reliable operations. These cooling devices consume a lot of energy and work on a 24-hour basis. Checks should be made of the computer server rooms, to ensure they are well insulated and to see if temperature rises occur in the summer.
If so, windows can be blanked to avoid warming effects due to sunshine. Another suggestion is to seal off unused rack spaces, so as to prevent cool supply air from mixing with hot server exhausts. Changing the layout of the room and installing partition walls around the servers may also minimise the amount of space to be cooled.
Most computers also remain turned on when unused. Although the power they need when idling can be relatively small, a company may face increased energy usage if there are many computers and they are continuously plugged in. Software applications may prevent power management settings from working effectively.
The use of third-party power management software can offer features beyond those already present in the operating system and thus bring significant energy savings.
Railway point heaters
Point heaters prevent railway points (also referred as switches) from freezing in extreme cold weather and are necessary to maintain smooth operation of a metro and light-rail network without disruption. However, point heaters consume a relatively large amount of energy. Most point heaters are powered by electricity, although some are powered by natural gas (compressed natural gas or CNG).
Old point heaters are switched on manually when weather forecasts predict the temperature will drop below zero degrees Celsius. Modern regulated point heaters automatically switch on when weather conditions (temperature and humidity) require activation. This saves energy, because the heaters setpoints are defined optimally, avoiding unnecessary heating.
It is essential to have good quality point heaters with efficient sensors, so that heaters always switch on when required by temperature and humidity. If the return on investment is low, manual switching must be considered by using an automated checklist at the traffic control centre.
Top contact third rail
Third-rail systems using top contact are prone to the accumulation of snow or ice. In order to avoid service disruptions, the third rail must be heated by the use of an electric resistance – which can consume a lot of energy. As a result, it is recommended that heating elements be remotely controlled by using intelligent controllers. The heating control is based on actual measurements of weather parameters via one or more weather stations. The weather stations measure temperature and wind speed and they detect rain or snow. The heating systems are only activated when there is a risk of ice forming, thus reducing the energy consumption and maintenance needs.Fig. 32 – View a a remote heating control system