Electrical Contracting News (ECN) March 2017 | Page 49

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 .
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 .
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