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Eaton Medium Voltage Technology Provides Safe Energy Management for Prestigious Hospital Project
- Published: Monday, 16 December 2013 11:51
Power management company Eaton has recently successfully installed a comprehensive Medium Voltage (MV) system for a new hospital in Zwolle, The Netherlands.
At 108,000 m2, Isala Klinieken is the largest non-academic hospital in The Netherlands and is now using Eaton’s innovative MV switchgear in combination with a Power System Automation (PSA) solution to help ensure a secure electrical energy supply for the complex.
Electrical energy is critical to a number of activities in healthcare. In collaboration with Eaton, the Dutch installation consortium ICI (Installatie Combinatie Isala) has focused on implementing a reliable and flexible system at the hospital with security as a main priority. As hospitals continuously increase in size it is important to minimise low-voltage distribution losses. Thus, the trend is to run the 10 kV supply deeper into the building.
“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”, said specialist engineer Gert Jan van Tolij from ICI.
After careful consideration, ICI selected a design that uses two 10 kV ring circuits and allows the supply to come from either mains or emergency power generators as required. One ring circuit supplies the preferential power supply system, and the other the non-preferential one, with any power outages in the preferential system being absorbed by emergency power generators.
The advantage of using open ring circuits is that faulty sections can be isolated, allowing other sections to remain functional and bottlenecks or Single Points of Failure (SPOF) to be eliminated. The two incoming 10 kV cables are also set a distance apart to avoid potential problems from excavation work.
At the heart of the installation is 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.
“We chose the FMX because of its innovative vacuum technology which allows for frequent and high levels of switching”, explains Gert Jan. “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.”
In case of a power outage, four emergency power generators are available to supply 1 MVA each to the preferential busbar of the Power Xpert FMX. These generators are connected with a step-up dry transformer monitored by positive temperature coefficient (PTC) elements with a PTC relay. 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 (UPSs).
The Central Control Panel (CCP) is the brain of the whole electrical installation. The CCP is part of Eaton’s comprehensive Power System Automation Services offering. For ICI it was a logical step to also choose Eaton technology for the control tasks: “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”, explains Gert Jan.
Redundancy has also been implemented within the control unit, which is equipped with two PLCs that communicate directly with each other and monitor each other’s functions. The PSA comprises a Central Control Unit (CCU) that efficiently manages all necessary steps should a power failure occur anywhere in the system. There are double feeds for the CCU that come from two 110 V DC Eaton units in each of the rooms in the power building. These units ensure that all the control, protection and switching actions are and remain available.
The power distribution system also includes equipment installed on the roof of the building with eight Magnefix Ring Main Units (RMU) and transformers supplied by Eaton have been fitted in a dedicated 10 kV room. The Eaton Magnefix was the system of choice as the 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. 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.