One of the most critical factors for any successful uninterruptible power supply installation is how it is project managed; transported to site and installed. The technology could be the best in the world but if logistics and installation are left to chance, disaster may strike.
Not many businesses today can ride through unplanned downtime. Chances are, that's what would happen if project and installation are mismanaged. UPS power protection loads will need to be powered down for as long as it takes to reconnect them to the output supply of the newly commissioned system and this will vary depending upon the complexity of the project, type, size and number of loads. Disruption to business can be minimised with sound planning and good management.
The Importance of Site Surveys. Installing UPS without a site survey is like running blindfold along a busy street. With little idea as to obstructions, direction or potential hazards, it is only a matter of moments before disaster strikes.
A UPS site survey consists of a set of fairly standard questions to establish specific information and areas for further investigation. It is typically a non-charged-for service provided by a qualified and experienced UPS supplier who will investigate logistical, environmental and electrical issues.
Logistics. Logistical issues centre on how the UPS and all associated equipment will be transported and delivered to site, positioned, unpacked and the suitability of its final location. It will consider restrictions or obstacles inside and outside of the building (whether it is a basement or upper floor location where stairs may be involved, for example), whether local authority parking permissions or Police attendance are needed for off-loading and what security and health and safety issues (as in the case of a chemical plant) need to be complied with.
UPS suppliers offer two categories of delivery: kerbside only and delivery, siting and positioning. Kerbside delivery is for smaller UPS (up to 40kg) that can be dropped of by the supplier to a central point within a site to be positioned thereafter by site staff or commissioning engineers.
Delivery, siting and positioning is a specialised service whereby the delivery company employs vehicles with tail-lifts and carries equipment such as trolleys and stair climbers. Larger UPS systems - including battery packs (pre-assembled or in kit form) will be supplied on pallets and require an on-site forklift.
Environment and Location. Environmental issues concern the specific location of the UPS and its associated system parts. This includes factors affecting its performance and operation; physical space, floor loading, ambient temperature, noise attenuation, vibration, dust and humidity, lighting levels and so forth.
Unless physical space is assessed, and the needs of the UPS in terms of air flow considered, the result may be a lack of space that may result in inadequate heat dissipation. Provision also has to be made for easy access for maintenance and inspection and connection and removal of loads and monitoring cables.
Floor loading can be an issue, particularly in computing environments, as many computer rooms employ false floors to allow air ducts for air-conditioning. In terms of UPS and associated battery strings, this may require the use of extendible false legs, placement on raised floor pedestals or a spreader plate to even out weight distribution.
Remote or split locations must be planned for in terms of how the UPS will be monitored. Uninterruptible power supplies generate a range of alarm conditions indicating an immediate or potential failure. Split locations may require additional cabling, monitoring and access. The same would apply if switchgear is to be housed in another area of the site or building.
Electrical Installation. Investigations into electrical installation are primarily concerned with suitability, protection, discrimination and compliance to regulations - both upstream of the UPS and downstream load connections.
The electrical supplies within a UPS system must integrate seamlessly with those already on site and not interfere with other equipment. The site survey will identify the scope of any electrical work, which must be carried out by certified and registered electrical engineers in accordance with local, national and organisation-specific guidelines. In the UK, the applicable standards are the Institute of Engineering Technology (IET) - BS 7671 IEE Wiring Regulations Sixteenth Edition and Electricity at Work Regulations 1989.
In addition, whether the installation is low or high power rated, it is mandatory that live conductors must be protected from overloads, short-circuits and earth faults.
Testing and Certification. The installation of a hardwired UPS, regardless of whether changes have been made to upstream or downstream circuits, requires the issuing of an Electrical Installations Certificate by a certified electrical contractor. Testing regimes vary, depending upon the UPS size and accessories installed alongside, but include earth fault loop impedance testing.
A UPS cannot provide the same quantity of energy, which is readily available from a normal mains power supply. The value returned from an earth loop impedance test will reflect the impedance of the UPS inverter. The two normal operation states of the UPS (mains present and mains power supply) must be taken into account when using earth fault loop impedance testing to determine fault currents and protective device discrimination.
It is true to say that innovative and sophisticated UPS technology is advantageous but without correct, appropriate and diligent project management, logistics and installation processes, it could be rendered useless. It is worth taking the time and necessary steps at the outset of any uninterruptible power supply project to determine what needs to be done to bring it to a successful completion.
ไม่มีความคิดเห็น:
แสดงความคิดเห็น