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Raritan Find My PDU Platform
24 April 2017
To an industry outsider, one could be forgiven for thinking that the selection of something as simple as a power strip would be quite straight forward. However, most of those who work in IT infrastructure will understand it is anything but! Raritan, a market leader in Network Power distribution and monitoring have recently made life for designers and operators much easier with the introduction of their on-line tool – Find my PDU. The ubiquitous PDU has evolved to become so much more than a supply distribution unit. It can have the ability, not only to monitor and control power feeds but act as a hub for environmental data collection within a cabinet. This is especially important in Data Centres. 

Let’s consider the typical specification requirements and choices to be made when selecting a PDU. Raritan has over 500 PDU configurations so using a tool like this can save a great deal of time for the specifier or buyer. 

Referring to the tool, the first choice is to select your region as requirements will differ between Europe, USA & Far East. Here we only consider European options. 

Input Phase: Depending on the power requirement, the supply will either be single- phase (1Ø), typically at 230V or 3 phase (3Ø Wye), typically at 400V. 

Input Voltage: The voltage will depend on the supply phase i.e. single or 3 phase. The European norm is 3Ø Wye 400V and 1Ø 230V but there are also options for 3Ø 415V (old UK voltage), 1Ø 208V (phase to phase in Delta configuration, found mainly in US) and 1Ø 220V (old continental voltage). 

Input Plug Type: The input plug will most commonly be a standard IEC 60309 plug in either a 16A, 32A or 64A 3 pin blue version for single phase or a Red 5 pin plug for 3 phase supplies. However, PDU’s can also be hard wired via an AC terminal or supplied with a cord but no plug, typically 3m length. 

Form Factor: The orientation of the PDU can be either vertical mounted, otherwise known as zero-U or 0-U as they take up no rack space or alternatively horizontally rack mounted taking 1or 2RU spaces. Vertical mounting is by far the most popular as aside from the rack space saved, the outlet sockets are conveniently situated adjacent to the servers and IEC power leads are kept to a minimum length. 

Input Current: There are three choices for input current: 16,32 and 64Amps. The higher the kVA (Kilo Volt-Amps or Apparent power), the more current that is required. 

Power: Power ratings vary up to 22kVA and as low as 3.7kVA, which will be determined by the total IT load in the cabinet. 

Inlet location: Power may be fed from above the cabinet or below so it is a necessary consideration where the inlet will be located i.e. the top or bottom of the PDU in the case of vertical orientation. The mounting location of the PDU may also determine whether the supply cable enters the PDU on the end or front face. 

Outlet count: Raritan provides a wide selection of configurations for the quantity and type of outlets. There are two types of outlets, the C13 and C19. The IEC C13 is a 10A receptacle socket for a ‘kettle lead’ C14 plug. The less frequently used IEC C19 is a 16A receptacle socket for heavier duty machines. Typically these are selected in banks of 4 providing ‘A’ and ‘B’ circuits for resilience e.g. 24 x C13 and 12 x C19. 

Metering & Switching: This is where the intelligence is defined and how the PDU is controlled. Let’s start with Outlet metering. Metering covers a range of attributes including Voltage (V), Current (A) or Active Power (kW) (per line, per breaker or receptacle), Real Power (kVA), Energy (kWh) and Power Factor. Accuracy is to within +/-1% which is adequate for billing purposes. The PDU is networked via an Ethernet Port or WiFi option as well as having an onboard colour display. Up to 8 PDU’s can be cascaded on a single Ethernet connection. 

Sensors can be connected to the PDU to monitor in-cabinet Temperature, Humidity, Airflow, Differential Pressure and contact closure (e.g. doors). With sensors, the PDU becomes not only an energy metering and fault monitoring hub but part of an environmental monitoring system. PDU’s can be remotely managed with the appropriate software via HTTP; SSH; Telnet; RS-232 (Serial); Power IQ; SNMP version v2/v3; SMTP and JSON-RPC. Metering can be selected as stand-alone or in conjunction with remote outlet switching. As well as metering and switching of the individual outlets, the PDU input lines can be monitored as a separate option with or without monitoring and or switching of the outlet receptacles. 

The selection table can be downloaded as an XLS sheet and specification sheets and drawings are available for each selection.