Secure electrical energy supply for new hospital

Since electrical energy is critical to a number of activities in healthcare, the Dutch installation consortium ICI has implemented a reliable and flexible system at the hospital, focusing on security as a priority.  With hospitals increasing in size it is important to minimise low-voltage distribution losses, therefore the 10 kV supply is usually run deeper into the building. ICI decided on a design using two two 10 kV ring circuits and allowing the supply to come from either mains or emergency power generators, as required. One ring circuit supplies the preferential power supply system, while the other supplies the non-preferential one. Any power outages in the preferential system are absorbed by emergency power generators. By using open ring circuits, any faulty sections can be isolated so that the other sections remain functional and any bottlenecks or Single Points of Failure are eliminated. The two incoming 10 kV cables are also set a distance apart to avoid potential problems from excavation work.

The installation uses Eaton’s Power Xpert FMX switchgear panel, an IEC single busbar, and solid- and air-insulated (SF6-free) MV switchgear for voltages up to 24 kV. The FMX units are set up to provide a non-preferential and a preferential part for each room and are connected using a specially made wall bushing with a coupling at the centre. Four emergency power generators are available to supply 1 MVA each to the preferential busbar of the Power Xpert FMX, should there be a power outage. The design of the installation distinguishes between three levels: the operation of two, three or all four emergency power generators. If a power failure lasts longer than 0.5 seconds, the emergency power generators kick in and emergency power is supplied within 15 seconds. Brief dips of less than 0.5 seconds are picked up at a local level by Uninterruptible Power Supplies.

Part of Eaton’s comprehensive PSA Services offering, the Central Control Unit (CCU) is the brain of the whole electrical installation. Equipped with two PLCs that communicate directly with each other and monitor each other’s functions, redundancy has also been implemented within the control unit. The CCU efficiently manages all necessary steps if a power failure occur anywhere in the system. It features double feeds that come from two 110V DC Eaton units in each of the rooms in the power building. These ensure that all the control, protection and switching actions are and remain available.

Eaton have also supplied eight Magnefix Ring Main Units (RMUs) installed on the roof of the building and transformers fitted in a dedicated 10 kV room. Since the Eaton Magnefix switchgear does not require a raised floor, it allows for the cable panels to be reversed and for the supply to feed from the top. The RMUs are set up in pairs in each wing of the building - one unit for the preferential and one for the non-preferential system. The power that is supplied from either the mains or the emergency power system via the Power Xpert FMX to the Magnefix is then transformed from 10 kV to 400 V.

Gert Jan van Tolij, Specialist Engineer, ICI, comments: “It is important that this voltage level is managed properly and that a fully reliable system is used to distributes it to all the wings of the building. The central control goes with the 10 kV input, so it has to work in perfect harmony with all the hardware. We would prefer not to have this managed by a third party. Eaton is familiar with the installation and knows best how to control it. We chose the FMX because of its innovative vacuum technology which allows for frequent and high levels of switching. The reasonable price and environmentally friendly aspect of the technology were also significant benefits. Even more important was the high power level it offers and the extremely compact design with slim panels.”

All the equipment used by Isala Klinieken meets international IEC standards and is available in the UK & Ireland for electrical power management applications at 11KV and 20kV.