Optimising PDU Technology: A Crucial Link in the Power Chain

The Power Investment

Power management at the equipment level within the rack/cabinet is a vital point in the power chain for the continual uptime of critical services. With all sectors now heavily reliant on data and it playing a vital role in everyday life any downtime has a massive impact on a brands reputation as well as the company’s bottom line. Whilst there have been several publicised data centre power issues in the last few months (all experiencing outages attributed to UPS failures/issues) we should not overlook the rack mount Power Distribution (PDU) element of the power chain.

“The end to end power system includes all of the components that are a part of the power distribution path, that is, the path to move electricity from the building utility service to the IT load.” – The Green Grid

Racking Up the Options

The current power distribution units being mounted into 19-inch racks/cabinets have an array of variables allowing the selection of the most suitable unit for the job. The rack configuration and subsequently the PDU requirements are often determined by the main stakeholder requiring the hardware. For example, AV (Audio Visual) specific racks predominantly require PDUs with UK sockets due to the types of equipment to be rack mounted.

The PDU technology level can vary depending on the physical location of the racks; a large hotel for instance would benefit from intelligent PDUs in racks located within the main equipment room where as individual floors within the hotel would have a lower level of intelligence required and basic metered PDUs could be installed.

There is an increasing variation of PDU configurations for different stakeholders, such as security, networks, facilities, as well as AV.

Main considerations include the level of intelligence required (basic, metered, monitored, strip level metered with outlet switching, outlet switched and outlet metering), quantity and mix of sockets, input plug types, cable length, feed input (top or bottom depending on the power feed into the cabinet being through the floor or from overhead), dual feed option, whether circuit breakers or individual fuses are required, and environmental sensors.

PDU mounting cannot be overlooked, vertical PDUs can be mounted taking up zero ‘U’ within the rack to ensure valuable hardware space is not occupied. Using mounting kits which are quick, tool-less and suitable for global branded cabinets saves engineers time and in turn company’s further installation costs.

Utilising further power management solutions, Automatic Transfer Switches (ATS) are ideal for single fed AV and network equipment and can be easily mounted into 19-inch racks.

Why Choose Intelligent Power Management?

In addition to having high levels of configurability at the various PDU technology levels there are major benefits from choosing intelligent PDUs for installations including the knowledge surrounding the data which is captured.

“An investment in knowledge pays the best interest” – Benjamin Franklin

Not only is data displayed locally on the PDU or a connected device mounted to the outside of the rack but it is also available remotely including current (AMP), voltage (Volt), power (KW), energy consumption (KWh), and power factor of the entire PDU. Power usage data can then be assessed, having been collated and reported using a web based GUI (Graphic User Interface) or integrated into an existing BMS. This data can also be used for inter-departmental billing or in co-location data centres a revenue stream providing accurate billing data to clients, if meter reading accuracy of the PDU is within +/- 1%.
Variations in requirements with power management are also determined by sectors before reaching internal departments. Education establishments are seeing greater storage requirement demands driven by increased research and development, big data and IOT technologies. Intelligent PDUs allow for capacity planning, departmental / faculty cross charging for power usage, environmental objective measurement on power usage effectiveness.

Many sectors including Finance require third party software integration via SNMP as well as hardware modifications within the power distribution unit itself. These can subsequently require global variations (voltage, input, socket types, etc.) for each geographic location/office

Reducing Power Outages

Regardless of sector or stakeholder ensuring hardware remains powered on without interruption is paramount as the costs and implications associated with downtime would cause a sleepless night for most IT / Data Centre Managers! Reducing power outages requires an examination and evaluation of all levels of the power chain however there are some simple yet effective ways to reduce the likelihood of power outages at the rack end of the power chain where it is imperative to keep IT equipment running.

There are a number of factors to consider with regards to the PDU’s that will reduce the chance of unplanned power outages at the rack equipment level providing further resiliency:

  • Coloured PDU Chassis allowing the identification of the PDU’s for technicians and engineers to reduce human error whilst working in racks/cabinets. The use of coloured PDUs also enables clear visual identification of the power feeds when redundancy is required. (Two PDUs per rack for primary and redundant, A&B, power feeds).
  • IEC Accidental Release Sleeves, power cord retention system for C13 and C19 sockets. Such solutions offer added protection against the unintentional removal of cables from the PDU C13 or C19 outlets.
  • Threshold alerts to highlight unauthorised or accidental removal of equipment. Setting low alert levels can notify nominated administrator(s) of removal of equipment from PDU sockets using SNMP.
  • Environmental Sensors will also allow setting of alarms and thresholds to provide early detection of issues within the rack. For example, temperature, humidity, smoke, water.
  • Selecting PDUs which have hot swappable technology such as a RMS current meter with LCD or field replaceable DC modules so there is no interruption to equipment in the event of a component replacement being required.

It is also worth considering whether rack accessibility should be upgraded. Whilst there is an increasing awareness for improving security beyond standard locks and keys, many rack installations would benefit from upgrades such as smart card access control. Reducing access to inside racks and preventing the unauthorised removal of equipment, alerts could be configured notifying administrators of unauthorised access attempts.

Given the mission critical nature of the environment the intelligent rack PDU must be designed, built and manufactured to provide extremely high levels of resiliency – areas that can be used to benchmark this are hot swappable digital local touchscreen display’s and hot swappable DC power modules that are typically used within the Metered & Outlet Switched (WS) PDU and the Outlet Switched with Outlet Metering (WSI) PDU models, probably most importantly the use of latch able relays at the socket or receptacle level that will always supply AC power or are always on in the event of component failure.