The Customer
The end client is one of the World’s leading financial institutions founded in 1801 and are based in the City of London. The project was to upgrade 4 x existing Standby Generators supporting their main Data Centre. Due to the fact that the replacement generators were being installed in the same area as the original machines, a complex installation of temporary equipment was required to support the building whilst the work was being carried out. This included 5 MVA of Temporary Generators, Temporary 11 kV Step Up Transformers, Temporary MV and LV Switchgear and over 4 km of LV and MV temporary power cabling.

Project Brief
The project required The Generator Company to Design, Manufacture, Deliver, Install & Commission 4 x 2,300 kVA Standby Generators with an output Voltage of 11,000 Volts AC. The project had several challenges which had to be overcome and a solutions demonstrated at tender stage, this included; overcoming the issue of limited space around the building and the method in which the generators would be craned onto the roof 7 story’s above ground level and also the method in which temporary generators could be connected to the building without any power outages. Work undertaken as part of the project included;

  • Design and manufacture 4 x 2.3 MVA generators with strict
  • requirements in terms of limiting vibration
  • Design and Manufacture new Acoustic Attenuators for the generator room due to the replacement generators having a 25% increase in output compared to the original generators
  • Provide Temporary Generators, LV & MV Switchgear, Step Up Transformers, and MV and LV load cabling to support site load during the generator replacement work.
  • Install and Commission temporary equipment including craneage to lift it onto a 4th floor roof.
  • Provide craneage to lift generators into plant room 7 story’s above ground level
  • Design, Supply, and Install a new Master Control Panel to control the clients existing suite of 11,000 Volt AC Switchgear consisting of 11 VCB’s, a remote 11 kV Switchboard, and 6 x LV Switchboards utilising a Fibre Optic network for each Circuit Breaker to communicate with the Master Control Panel PLC.
  • Supply and Install a new Neutral Earthing Switchboard and Resistors
  • Temporary Standby Generator Installation

Temporary generators were installed prior to the permanent upgrade installation to ensure the building had continuous standby power whilst works were carried out. Our Rental Division, “Powerhire”, supplied and installed 4 x 1250kVA, 415 Volt AC, 20ft Containerised Rental Generators on a 4th Floor Roof on one side of the building. Also installed were 2 x 3.15 MVA 415 Volt AC to 11,000 Volt AC Step Up Transformers, a 6,000 Amp Temporary Generator Switchboard Housed within a 20ft ISO Container, Temporary 11,000 Volt AC Switchgear and Load Terminal Boxes for jointing temporary load cables onto the existing cable network, and the provision of over 4 km of temporary 240mm2 HO& single core load cables installed on Triple Stacked Cable Tray.

New Generators
The 4 x new 2.3 MVA MTU Powered 11,000 Volt AC standby generators had to be carefully designed to take account of the limited space within the existing generator room sized for smaller generators, another important design element was to give consideration to limiting any vibration from the running generators upon the steel frame of the building. The generators were fitted with local generator control panels that were connected to slave controllers fitted on the Master Control Panel (MCP) located at -3 Basement level in a room adjacent to the buildings main 11 kV Switchboard. 2 x Local 2,000 litre fuel tanks were installed within the generator room at roof level and to comply with fire regulations these were clad inn Durasteel. The existing pipework from orginal 30,000 litre Bulk Fuel Tank in the basement was tested and connected to the new Fuel Day Tanks after a set of fuel transfer pumps were fitted.

Careful consideration also had to be given to the method in which the new engine exhaust systems were supported within the generator room and calculations had to be carried out to assess the load bearing ability of generator room ceiling that had to be removed to facilitate installation of the new generators. The new MCP had to be designed to control and existing 13 breaker 11,000 Volt Main Switchboard, 1 x new 5 breaker 11,000 Volt Switchboard, and 6 x LV Switchboards used for load shedding. The clients requirement was that an outstation would be installed in each of the switchrooms and these would be connected to the MCP with a Fibre Optic Ring.

A part of the installation work the existing acoustic steel roof of the generator room had to have a section removed to facilitate each of the original 4 generators being removed and the 4 x new generators being installed. The specification required all of the original equipment stripped from the original room and replaced and this included; Fuel Tanks, load and control cabling, air inlet and outlet attenuators, engine exhaust systems, fire alarm cabling, small power and lighting, and fuel pipework. The only items that remained were the generator output cables. The installation aspect of the project had to be carefully planned around other work being carried out as part of the main contract. One of the challenges of the project was to source a crane that was suitable to lift the 35,000 kg generators onto the roof when the roads surrounding the building were not large enough to accommodate such a crane. At tender stage our installation team designed a solution whereby a relatively small crane could be positioned in the courtyard of the building above the three story basement car park and utilise heavy duty props carefully positioned on each of the car park levels to support the additional weight of the crane and equipment being lifted on the courtyard floor. This solution negated the requirement to have any road closures allowing greater flexibility in terms of the timing of each lift.

New acoustic inlet and outlet attenuators were fitted into the generator room to accommodate the 25% increase in output of the new generators. As each new generator was craned into position within the refurbished generator room they were lowered to ground level and then skated into position by our own skilled team of installation technicians. Once all of the new equipment had been craned into the room the section of roof was replaced and sealed to prevent water ingress.

Off Site Testing & Commissioning
A requirement of the project was that the complete temporary installation was tested off site prior to delivery, this work was carried out and witnessed by the client at our Main Rental Depot in Dover, Kent. The new generators were witness tested off site in pairs and extensive testing was carried out to prove that the vibration was within the parameters set for the project. To achieve this additional anti-vibration mounts were installed between the underside of the generator base frame and the floor. Full simulation tests were also carried out on the new Master Control Panel (MCP) with all of the outstations and Neutral Earthing Switchboard connected using out own test rig at our factory located in Rochester, Kent.

Extensive testing of the new equipment was carried out on site to prove each aspect of the installation prior to the temporary generators being disconnected. This included installing temporary Transformers and Loadbanks from our own rental fleet to enable the generators to be run at their full operating load of 9.2 MVA. The new generator installation exceeded the end customers’ expectations and was accepted after the first set of tests.

On satisfactory completion of testing and commissioning on all new equipment the temporary generator package was removed. Generator IST and client training were provided prior to completion of the project. The project was satisfactorily completed on time, with minimal interruptions to the live site and within the budget allocated.