After reviewing the options, they specified the GenieEvo from Schneider Electric, a system that fulfilled their safety needs and met a requirement for remote switching and metering.
Daresbury Laboratory is operated by the Science and Technologies Facilities Council, a body which enables a broad range of scientists to do the highest quality research work. It hosts resources and services of strategic importance for the research community and employs around 350 staff . The facilities are used by thousands of scientists and engineers mainly from the university research community.
Estates Facilities Manager, Nigel Henshall, explains the decision for the change of switchgear: "We have two direct supplies from Scottish Power coming in to a 26 panel switchboard which distributes 11,000 volts to transformers around the site. The oil-filled switchgear had been in place for around 40 years. Because of its vintage it was robust and with proper maintenance could be considered relatively safe. However, if something goes wrong with this type of equipment the results can be catastrophic. HSE guidelines recommend a replacement programme for oil-filled switchgear and having carried out a risk assessment, we believed that to fulfil our duty of care it was necessary to update to a safer technology."
In terms of capacity, the Daresbury engineers were looking for a like-for-like replacement with the addition of some extra panels, and key determining factors included the ability to remotely monitor energy usage and to have remote switching. More specifically, the company wanted an equipment supplier who could provide the necessary software as an integral part of the package. Nigel explains: "We need to meter radial feeds to specific parts of the Laboratory so that we can re-charge usage. We had been finding a mismatch between the reading figures supplied by the power company and those of our sub meters. For higher accuracy, we wanted to introduce tariff grade metering but we were concerned that this might mean we needed to involve a third party to provide the software that would enable us to extract the information from the system. This was a major factor in our decision to use Schneider Electric’s equipment."
In considering the alternative types of switchgear, the Daresbury engineers looked at gas-filled and vacuum technologies. Having visited the manufacturers to get experience of personally operating both types of equipment, the team chose Schneider Electric’s GenieEvo vacuum-based system. Henshall said: "The vacuum circuit breaker technology reduces the panel size and has a number of inherent safety features. On top of this, Schneider Electric was able to offer a turnkey approach, supplying the complete package of hardware and the software necessary to enable us to carry out remote monitoring and metering. Being able to provide this package met one of our major concerns."
A low-maintenance system, Schneider Electric’s GenieEvo switchgear has a disconnector and earthing switch which are sealed in an earth-screened cast resin enclosure containing controlled air, which eliminates the need for regular cleaning of the copper contacts throughout the product’s life. Incorporating Schneider Electric’s Evolis vacuum circuit breakers, the GenieEvo is fully internal arc rated to 100% of the switchgear’s breaking capacity to ENA TS 41-36.
For advanced protection, the switchgear integrates Schneider Electric’s Sepam relays, which offers comprehensive protection, metering, control, monitoring and annunciation functions.
For Daresbury Laboratory, the GenieEvo was supplied with a full SCADA and metering package. To meet the requirement for remote switching for additional safety, a remote panel was installed which enables engineers to carry out the switching function. In addition, the equipment can be remotely controlled and monitored via PC, using a standard web browser.
Installation of the switchgear was carried out by Daresbury Laboratory’s maintenance contractors NWP Power Systems, who have considerable expertise in working with Schneider Electric’s equipment. Commissioning engineer, Dave Parry, described it as ‘very user friendly and well designed’.
Close collaboration between Schneider Electric and NWP at every stage resulted in a speedy and successful commissioning of the switchgear as Nigel Henshall explains: "NWP worked very closely with Schneider Electric on the specification of the equipment. In particular, we had to ensure that we got the interfaces with existing low voltage equipment right as faults on either side would have resulted in inter-tripping. Timing on installation was also critical as although the switchboard has two incomers so that the site is fed by two halves, when it came to replacing the bus section we had to have a power outage across the whole site. The two teams planned and co-ordinated this so that it could all be done in one day."