6 off 2500kVA Paxman powered 11kV generating sets all housed in two dedicated plantrooms.

The generating sets are installed on the fourth floor of a 32 storey building constructed for Barclays Bank.

Due to the location of the generating sets, a major problem to overcome was noise emission from the sets as there were occupied spaces on the floors both above and below the generator rooms. To comply with the stringent noise level specified, the generators were installed in two site-constructed internal acoustic enclosures that each encompassed three generators.

The generator control system incorporated a Dual Redundant PLC system, split into two halves and separated in different switchrooms to improve resilience, to provide a site-wide load management system including remote I/O control panels and HMI graphic displays depicting power flow across the various HV switchboards.

Broadcrown`s scope of supply included the supply and installation of the generating sets including the acoustic enclosures and noise attenuation, extended twin-wall stainless steel exhaust systems, local fire-rated day tanks, generator control system, HV link boxes and neutral earth contactor/resistor panels, together with commissioning and Integrated System Testing with other trade contractors.

3 off 2750kVA MTU powered 11kV generating sets individually housed in ISO style containers.

The generating sets are installed on the roof of an existing 10 story building in central London, being occupied by J P Morgan Chase Bank.

The challenging requirement of this project was to fit the generator containers onto an already overcrowded roof space.

Added complications were the stringent noise level of 63dba at 1 metre with two generators running which, for such large sets, required special attention to the design of the acoustic containers, and the height restriction imposed by planning constraints for the roof mounted plant, which resulted in mounting of the exhaust silencers at low height on the side wall of the containers.

An additional container was also installed at roof level to house the Generator Master Control Panel (incorporating Dual Redundant PLC system) and the Neutral Earth Contactor/Resistor Control Panel.

To allow for cranege limitation on site and following successful works testing the generators and the generator containers were broken down into component form to reduce each lift to within the capability of the site crane. The components were then re-assembled at site and successfully commissioned.

Broadcrown`s scope of supply included the supply and installation of the generating sets including ISO style containers, externally mounted local fire-rated day tanks, two off 38,000 litre bulk fuel storage tanks (located in the basement) together with the installation of welded double skinned feed and dump pipework between the roof mounted generators and the basement bulk tanks.

1 off 2000kVA 11kV Perkins powered generating set housed in an acoustic enclosure.

This generating set was provided to synchronise and load share with three existing Broadcrown generators at this site.

The existing generators were located in the basement and were remotely cooled via air blast coolers that are located in a well at roof level.

The problem facing Broadcrown was that there was no available space in the basement for the installation of the 4th generator. Following discussion between the contractor and Broadcrown Sales Department it was agreed that the new generator could fit in the well where the existing air blast coolers were located, at roof level of a 34 storey building.

Broadcrown undertook to remove the air blast coolers from the well, re-install them directly on the roof of the building, re-connect them with temporary pipework to the existing generators cooling system, re-test the existing generator to make sure the movement of the coolers had no detrimental effect on existing generator operation. This was done generator by generator as this was a live building and thus it was imperative that the generator back up supply was available at all times.

Once the coolers had been moved to their temporary location, the new generator was positioned in the light well. As the building was existing the only possible way to get equipment to roof level was by a contractor-supplied tower crane installed on the roof of the building. The generator and the acoustic enclosure had to be stripped down to within the 10,000kgs capability of the crane. Lifting from the road side of the building was not possible, therefore the generator components were lifted on to a barge and floated around the waterways to the opposite side of the building and the crane lifted the components from the barge and onto roof level (34 storeys).

Following re-assembly of the generator in its acoustic enclosure, Broadcrown installed a steel gantry over the generator enclosure, which had to be low height with side mounted exhaust system. Special attention was given to air flows in and out of the generator enclosure because the gantry became the permanent location for the air blast coolers. These were then disconnected from their temporary position and re-installed on to the gantry and again this had to be done without affecting the generator back up supply to the building.

When the re-located coolers were re-commissioned the new generator could then be commissioned with the three existing generators.

Broadcrown's scope of supply also included the provision of a basement mounted fuel transfer system together with approx 170 metres of feed and dump welded double-skinned pipework from the basement to the roof, together with changes to the bulk tank installtion to incorporate the connection of the day tank for the additional generator.