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How to Select the Appropriate Power Distribution Unit

Power Distribution Units (PDUs) have emerged strongly as an ideal solution for raising the management and power availability of a system. In datacenters, they are critical for power conditioning of equipment installed in cabinets and racks. To learn more about this element within an IT infrastructure, Tripp Lite advises on how to select appropriate PDUs for network, server and telecommunications applications.

A Power Distribution Unit (PDU’s) reliably distribute power to equipment installed in racks and cabinets and allow network administrators to remotely monitor power usage and control outputs. With this in mind, data network administrators or the staff assigned to maintain these systems are faced with the fundamental responsibility of selecting a reliable power source for their equipment.

What are PDU’s?

PDUs are an effective and strategic piece of equipment that provides secure power to data network systems by increasing power availability and manageability when properly selected and installed. The primary function of the PDU is to conditionally distribute power received from a system or generator through a power outlet. These units are built with different outputs to meet the growing power needs of today's densely packaged rack enclosures, which house other related equipment with up to 80 input plugs for connections.

These units are also considered essential conduits for rack-mounted equipment such as data network systems and the like.

PDU Classification

One of the main issues to be addressed when selecting PDUs for a data center application is the need to balance the relatively high cost of a switched Power Distribution Unit compared to the relatively low cost of a basic PDU model.

Basic PDUs are, as the name implies, basic in their functions. They provide a simple - but very reliable - power distribution to various equipment. They feature multiple outputs, a long power cord, and versatile mounting options. Their advantage is the ability to have sufficient outputs for the safe operation of the many networks, servers and telecommunications equipment that require continuous power.

Monitored PDU’s, on the other hand, offer the ability to remotely monitor operation and alert to avoid overloads that can cause downtime. This is made possible by the built-in Ethernet interface, which allows users to manage PDU’s over the IP network using SNMP, a standard Web browser, or telnet. The programmable alert system monitors load thresholds and reports alarm conditions via automatic email, SMS and SNMP. The PDU can be managed through the included PowerAlert Network Management System or through a third party network management system. Another excellent additional feature of monitored PDUs is Envirosense, which allows the user to monitor temperature, humidity, alarms and contact closure interface.

Switched Power Distribution Units offer a more convenient way to avoid interruptions in network operation. They have the same features as basic PDU’s but also include a digital load meter, which allows network administrators to monitor the total power consumption (in amps) of equipment connected to the Power Distribution Unit. As the equipment is added, administrators can visually control the load increase and take preventative measures to increase input capacity (by adding more or higher capacity systems or service circuits).

Switched Power Distribution Units give network administrators the ability to remotely reboot locked devices. The switched PDU has a built-in network interface that allows administrators to remotely control power to the various PDU power outputs via an Ethernet network connection, and extend the runtime of critical equipment during a power outage or blackout.

Implementing and Installing a PDU

PDUs can be installed in most rack enclosures horizontally or vertically. Horizontally mounted PDUs occupy one or two rack spaces, while vertically mounted PDUs do not occupy rack space. Since their primary function is to serve as the entry point for the rack power supply, most PDUs come with a 10 to 15 foot input cable. With their long input cables, PDUs can be mounted anywhere within the rack enclosure, even at the top of the rack, and still remain connected to a distant power source.

The important thing when choosing a PDU is to select units that not only help reduce energy consumption costs but also help promote greater efficiency and productivity.