The engineering work speed restriction signal is used as a temporary signal to inform the driver of the train to slow down.
TWhen engineering works are being carried out three signals have to be provided for each section of track and for each direction (UP and DOWN):
- Slow down warning signal
- Start of speed restriction
- End of speed restriction
The slow down and speed restriction signals have different characteristics:
- Slow down warning signal: yellow hexagonal backboard with two yellow lights set diagonally
- Start of speed restriction signal: yellow rectangular backboard with two yellow lights set vertically
- End of speed restriction: green rectangular backboard with one green light
In general the slow down and speed restriction signals do not require a special power supply and are provided with batteries.
There are also slow down and speed restriction signals for installation inside tunnels. In this case these are the same as the lineside signals with the difference that the size of the backboard is a lot smaller.
The functional architecture of the slow down and speed restriction signals is independent from the type of installation (lineside or inside tunnels). For normal operation each signal is provided with its own rechargeable lead battery pack.
For installation within tunnels of a signal with three lights (one for start of speed restriction and one for end of speed restriction) three battery packs are provided.
In addition to providing voltage the power control unit also has a logic circuit that shuts down the signal when the battery voltage reaches its minimum value thus protecting the battery itself from being damaged. The backboard is made from aluminium and is covered with a reflective film the shape and colour of which depends on the type of signal. One or two LED optical units are installed at the rear together with the power supply units.
The solar panel charging system allows two batteries to be charged at the same time.
In the case of permanent connection of the solar charging system, the effect obtained is that of a recovery of the partial discharge of the batteries during night time working.
Special light sensors are provided to ensure that the photovoltaic panel provides energy during daylight. The signals for installation within tunnels are similar to the lineside ones apart from the battery connection for the start and end of speed restriction signals.
|Signal Power supply||Battery
Battery + photovoltaic panel (outdoors only)
|Battery Rated Voltage||12Vcc (Protection by 10A fuse within the power supply module)|
|Minimum Voltage shutdown||10.8V±1%|
|Battery Capacity||24Ah (max 3 batteries)|
|Battery life||>500 hours (25°C)|
|expected battery life||(10 years)|
|Optical groups Input||10mA±5% (for each individual unit)|
|Dielectric rigidity||>2000V, 50Hz|
|Insulation resistance||> 10 Mohm|
|Operating temperature||-25 ÷ 70 °C|
|Optical group||YELLOW: 19 LED
GREEN: 19 LED
|MTBF||> 200,000 hours|