Monitoring the health of electrical infrastructure

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    Gareth Brunton, managing director of Bender UK, explains how the company’s residual current monitoring technology can reduce the need for shutdown and maximise the availability of healthcare facilities 

    Electrical installations in UK medical facilities are subject to periodic inspection and testing as required under BS7671 Part 6. This can be costly and intrusive for large group two electrical installations serving critical care facilities or operating theatres. The switch-off process can also be extremely difficult to schedule with the risk of unforeseen issues when the system is switched back on and returned to service.

    Maintenance teams must manage this issue to complete testing and meet statutory requirements. Failure to do so can result in danger to personnel or patients, punitive action, unplanned outages and, ultimately, system failure.

    The maintenance team is also responsible for the power to critical services and is required to deal with emerging maintenance issues and faults. Consideration should be given as to how new technologies can help it deliver the same solution and enable it to identify and action problems before they become critical.

    Bender has developed a system for the continuous monitoring of the electrical infrastructure within healthcare facilities that can remove the requirement for the shutdown necessary to carry out statutory safety testing.

    It can also improve availability and provide early warning of developing issues to enable predictive and preventative maintenance. Residual current monitoring systems (RCMS) also continually monitor the integrity of the electrical system, providing early warning if a problem is detected.

    Most monitoring systems flag up faults only down to the standard 30 mA required for personnel protection but ultra-sensitive RCMS are designed to identify faults down to 2mA. This capability alerts maintenance teams at a much earlier stage in their development, giving time to plan an intervention and rectify the fault instead of having to react urgently when it becomes critical. The ability to predict faults and plan service regimes means more effective use of resources and less downtime of vital high value facilities.

    A TN-S system is the most common type of earthed electrical system (in TN-S the T stands for earth – the French ‘Terre’, N for neutral and S denotes that the protective (earth) and neutral conductors are separate). An IT system has no active conductor that is connected to earth. Due to the lack of a low impedance connection between the transformer star point and protective earth (PE), a high fault current does not flow when a first insulation fault occurs.

    Consequently, there are no shutdowns and a single fault will not automatically prevent the system from operating. However, it will trigger an alert to signal that a fault has occurred, giving early warning of an issue. In addition, when a first fault occurs within an IT system, hazardous fault currents cannot flow due to the lack of a low impedance connection between N (neutral) and PE, and therefore, the risk of fire is significantly reduced. IT systems are typically installed only in critical locations such as group two medical locations. The remaining electrical installation across any facility will usually be an earthed TN-S system.

    Periodic inspection and testing dictates that the integrity of the insulation must be verified. This cannot be done without interruption to the service. Equipment and/or protective devices must be disconnected prior to insulation resistance measurement because they may not be able to withstand the test voltage used.

    Often, such additional effort and the shutdown of the power supply involves high downtime costs. In addition, restarting the installation is complex or not possible at all (for example, in intensive care areas). Any switching or transferring of loads also further increases the probability of an unplanned outage.

    Section 622.2 of the BS7671: 2008 wiring regulations states that a continuous monitoring system with a suitable management system can negate the need to carry out periodic inspection and testing, substituting a less intrusive process that avoids disconnection of loads. It must demonstrate that an adequate management system has been put in place to ensure that “an effective regime of continuous monitoring and maintenance” exists.

    Effective monitoring

    An effective monitoring solution must conform with the requirements of BS7671 Chapter 62 Periodic Inspection and Testing, therefore a documented process of engineering activity is required.

    Confirmation of the installation status can be managed by a continuous online monitoring system using RCMS in conjunction with Bender’s cloud-based reporting software – Powerscout. The system also fulfils the requirements of record keeping as detailed in Regulation 622.2.

    Powerscout integrates data from Bender’s RCMS, Power Quality Monitors (PQM) and third party universal measuring devices and is particularly suited to healthcare facilities. Powerscout continually reports on the status and condition of the site’s electrical infrastructure, enabling pro-active maintenance and preventing unplanned downtime.

    The software continually collects measurements and generates user-specific reports. This detailed information provides the basis for measuring without switch-off. Used together, RCMS technology and Powerscout can provide on-demand information on the entire electrical infrastructure including the integrity of the insulation. The storage of historical data and the ability to trend systems to identify potential degradation over time meets and exceeds the requirements of an ‘adequate management system’ as defined under Regulation 622.2.

    Continuous monitoring gives estate and facility managers an accurate real time picture of the entire data for single or multiple site locations, delivering all the information they need direct to a desktop or mobile device, with all measured values automatically and continuously saved.

    Data can be accessed remotely only by authorised site staff or service partners through secure web interfaces. The software can be individually adjusted to the customer’s system and monitoring requirements to create a precisely tailored solution for each customer.

    Importantly, the automated report on residual currents and power quality enables verification of the integrity of the system without switch off and is designed to fulfil IEC 60364-6 requirements for periodic verification of low voltage electrical installations. The safety and integrity of electrical systems within critical environments can therefore be managed without the need for shutdown and restart, with no interruption to service.

    Increasing profitability

    With RCMS, the facilities team can determine specific test intervals based on practice. This can remove, reduce or extend the test intervals for insulation resistance measurement.

    Depending on the use of the equipment, it is possible to set the intervals for periodic testing involving insulation resistance measurements to suit both safety considerations and commercial operating needs. Shutdowns for conventional insulation resistance measurements, even only for short periods, are no longer required due to the specific use of RCMS. The availability of an electrical installation is increased as potentially hazardous currents are located at an early stage in the process, minimising costly, unplanned outages. Costs incurred for the insulation measurement during the periodic testing of electrical installations and equipment are also minimised as works can be planned to match the needs of the business.

    Electrical safety testing and inspecting without downtime increases system availability and helps minimise unplanned outages, a significant cause of lost revenue. It is a practical and affordable solution that can enhance safety, increase profit and boost revenue. The system has already been accepted by the leading testing authorities and is being installed in hospital critical areas throughout the UK and Ireland.

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