Specifications

3U Traffic Outstation Handbook
667/HB/26568/000 Page 23 Issue 15
3.2.4 Support Batteries
The unit can be fitted with two rechargeable batteries.
The first is the optional Unit Support Battery, which supports the entire unit including
the modem, for a minimum of four minutes under all conditions in order that the
OMCU may inform the Instation of a mains power failure.
Note that some units, e.g. MOVA only units, do not require and will not be shipped
with a Unit Support Battery.
The other, the RAM Battery, is always fitted and supports the RAM memory and the
Real Time Clock during power failures for an excess of 7 months. On Issue 4 and
later CPU boards this battery is plug-able to allow easy replacement.
Newer processor boards include a ‘Gold Cap’ capacitor that allows the RAM battery
to be changed without loss of RAM data. The Gold Cap device provides a minimum
of 30 minutes support.
The two batteries have the following specifications:
Battery Type Support
Unit Battery 12V Lead Acid 20 minutes (Typical)
RAM Battery
Nickel Metal Hydride
418/4/39820/000
In excess of 7 months after
the Unit Support battery of 20
minutes has expired.
3.3 MECHANICAL
The construction of the unit is based on the standard 3U high, IEC297 Eurocard rack
system. The unit does not use the conventional back plane approach. Instead it uses
an expansion bus (see section 2.8 on page 21), to interconnect the boards
electrically. It does not require the rack to have guide rails, but if present they need
to be on 25.8mm spacing. Mechanically the boards are held in a stack, by four sets
of pillars and fixings, and held in place on a mounting plate. The mounting plate, also
accommodates the Modem and PSU assemblies, and is used to fix the total unit
assemblies to the 3U rack, or cabinet mounting side angle bracket.
3.4 ENVIRONMENTAL
Temperature: -15°C to +60°C ambient
Humidity: 20% to 95% non condensing at 40°C