Electrical Contracting News (ECN) March 2017 - Page 49

UPS & POWER DISTRIBUTION SPECIAL FEATURE time spent troubleshooting the source of problems and can simplify load balancing. Other features that can keep costs down include a low profile form factor. It’s also worth looking for rack PDUs with low profile circuit breakers or which are width optimised for side mounting. This prevents interference with the rail that can block hot-swap fans and power supplies, it also minimises the time required to service the rack in the event of component failure. Ease of installation is also worth bearing in mind. Not only are they more convenient and of course time saving, rack PDUs that are easy to install save on start-up and provisioning costs for customers making them an easier sell. Tool-less button mounting options for rack PDUs ensure out-of-box to install time is minimised, this solution requires a rack enclosure with keyhole (tool-less) mounting capability. ‘Within power distribution there is a real opportunity for electrical contractors to increase project value.’ Mounting flexibility Using the same vendor for rack PDUs and rack enclosures can avoid compatibility issues if that is a concern. Another way is to ensure the rack PDU has been designed for mounting flexibility. An ideal solution would have the tool-less buttons factory installed on the PDU. This would accommodate the rack metal thickness and would have the flexibility to be mounted on the side for 90˚ mounting. What’s more, other mounting options may be required, so that further flexibility can be obtained, if the rack PDU has bracket mounting capabilities such as a clip foot bracket. In addition, a rack PDU with a lightweight aluminium chassis, which is 30 per cent lighter than a steel equivalent, is also easy to install. It can even reduce shipping costs, plus it can dissipate heat better and deliver improved electrical ground conductivity. The process of selection should begin with the power rating of the PDU, when designing a data centre, operators typically take into account the planned capacity of the rack to calculate power and cooling requirements. Rack capacity is then used to select the appropriate input plug for the rack PDU. Companies want a device capable of carrying the full power load, as well as offering the possibility for capacity expansion in order to future proof. Any excess capacity that is being provisioned can be handled seamlessly simply by implementing a larger capacity PDU. Once the power is considered, the next step should be to evaluate the available technologies. Typically, rack PDUs come in three technology categories: basic, metered, and managed/switched distribution. Moving up the stack from basic to metered will allow companies the ability to locally measure current and load balance. It also enables the capability to remotely monitor branch circuits and facilitate capacity planning. With advanced metering, there is an opportunity to gain the capability to meter power at the outlet level. This important functionality is required for accurate Level 3 power usage effectiveness (PUE) calculations. Outlet level metering also provides a level of granularity in reporting power usage, which is often required in multi-tenant racks at colocated facilities. In addition, managed PDUs facilitate outlet switching which is an ideal function for lights-out operation and in situations where a fast response to remotely cycle power in the rack is needed. Furthermore, businesses can also turn off outlets when not in use thereby preventing accidental overloading of the rack PDU. Finally, outlet switching enables the ability to sequence power up and perform load shedding. These are advanced features that can be important elements of an overall power strategy. There can be no doubt that within power distribution there is a real opportunity for electrical contractors to increase project value and offer customers a wider level of support for their power monitoring and management needs. It’s up to contractors however to seize the opportunity and reach out to experts in the field should they need assistance. By addressing the above, electrical contractors can make informed recommendations and choices and potentially reap the rewards in terms of increased revenue. When designing a data centre, operators typically take into account the planned capacity of the rack to calculate power and cooling requirements. IT INFRASTRUCTURE SOFTWARE & SERVICES www.rittal.co.uk