FrontierDC’s enabling technology partner, Cannon Technologies, was approached by its customer Siemens, who were working on a contract for Great Western Rail; they required a cabinet to hold their electronic equipment which was to be used on the upgrading of the “Customer Information Technology System” being installed across the infrastructure. The installation would also incorporate a CCTV security system.
Although the systems were for use within the Great Western Rail franchise, the cabinet had to comply with the requirements of Network Rail as they would eventually have to approval its use within their rail infrastructure.
The major problem posed by Siemens was the amount of heat being dissipated by the equipment being used and the maximum acceptable working temperature. The estimated heat dissipation figure specified was in access of 1100-watts with a calculated solar gain equal to 360-watts.
Because of the reluctance by the various bodies involved on the use of air conditioning due to the level of the technical service engineers involved in the maintenance, Cannon were limited to the use of its excellent “Forced Fan Ventilation” system.
The cabinet was designed around the “Forced Fan Ventilation” system which gave a Δt (delta t) of just +5ºC and a maximum +7ºC at a high ambient air temperature of 35⁰. This was achieved by using two 220-mm diameter radial blowers, each fitted with finger guards for operator protection during the periodic servicing requirements. These were positioned within the hinged roof void giving an N+1 solution. The roof was supported in the open position by a bonnet type stay bar.
The fan type selected was based upon the heat being dissipated by the internal equipment and the effect of “Solar Gain” upon the outer skin of the cabinet. The “Forced Fan Ventilated” system works by drawing fresh ambient air into the cabinet through replaceable filters incorporated within the doors which also have in-built bug screens. The filters have a large dust holding capacity so cleaning/replacement can be accommodated within the normal equipment maintenance routines.
The fans are powered via an independent 48-volt DC power supply, and are fully controlled and monitored via a “Cannon Guard” system.
The Environmental Monitoring and Control system (EMC) controls the fan speed against temperature thus giving a cost saving to the customer by reducing the fans speed during low temperature conditions. It also provides any alarm contacts required, typically temperature out of limits, door open, fan failure etc.
The cabinet was configured with doors to both front and rear faces allowing for access from both sides of the electrical equipment being integrated.
Security/locking were provided by the Cannon Technologies stainless steel swing handle lock driving a multi rod locking system. The construction of the cabinet consisted of a dual skin and a thermally insulated internal chamber giving maximum protection against the effects of both solar gain and long wave radiation.
The cabinet was designed to be installed onto a standard Network Rail pre-cast concrete plinth.
The cabinet was fully environmentally tested within Cannon’s computer controlled environmental test cell and proved its ability to conform to Siemens specification. The excellent results gave the client the confidence to award Cannon the contract to supply the cabinets for use on this project.
Internally mounted within the thermal chamber and positioned to the underside of the internal roof panel was a low powered AC LED strip light, this is switched on when the door is opened.
Cannon also provided integration of a small 6-way consumer unit complete with a double pole 100-amp RCCB incomer and 6-off 20-amp single pole MCB’s all mounted on a 5-U high mounting bracket which also carried a13-amp dual RCB socket for use during customer configuration and site testing/set-up.
The general internal integration consisted of ESD button, fitted and labelled and located close to the mounting rails, all terminals were labelled and earth bonding labels attached to the bonding points for clarification. All electrical work carried used our qualified and approved electrical engineers; it was fully tested and certified.
Since the completion of this project the client has returned to Cannon and specified the cabinets use on many other projects.