Key Considerations When Selecting a Smart PDU

New IT cooling technologies, including in-line cooling and aisle containment systems, where most electrical energy is used, have been extensively discussed to reduce energy use. Electrical power distribution can also be optimized, although it requires reviewing a rack's Power Distribution Unit. 

Choosing a smart PDU involves five factors:  

Is it effective?

Consider these factors while choosing a PDU power distribution unit to distribute power:  

How much current does the PDU need? This depends on the PDU's linked IT devices' power usage. Match the PDU to the nearest amp rating, such as 3.16 or 32.  Need single- or three-phase power? Again, this depends on IT device consumption; a three-phase PDU may be needed when demand surpasses 8kW per rack. What type and number of sockets do I need? 10 servers require 10 sockets. Devices usually define socket type. C13 outlets rated for eight amps, C19 outlets for 16A, or a mix of both are used internationally. Is intelligent PDU metering and switching necessary? Remote monitoring and socket switching can transform your power consumption awareness. They also boost resilience.  Is it efficient?

We must monitor power and respond with methods to cut it. 

Monitoring can be done at the smart PDU's incomer for total power drawn or an individual device's socket requests. The latter provides more granularity for analysis, but meters' accuracy can range from one to five percent, so check the technical parameters. 

PDU electronics can require six to 60 watts, which can be substantial in a large data center. Intelligent PDUs in a 200-rack data center with twin PDUs can consume 2.4kW or 24kW. 

Using the switching capability, users can remotely shut down sockets and 'hard boot' connected devices. Check if the power distribution unit has a monostable or bi-stable switch device or relay. The monostable needs constant electricity to change state and stay there. Returning it means turning off the electricity.  

The bi-stable needs electricity pulses to change state and return. Thus, bi-stable uses less electricity than monostable, which might be significant as several sockets use power. 

Is it reliable?

Beyond 80,000 hours, bi-stable relays have a larger Mean Time Between Failure (MTBF) than monostable relays. Since most PDUs operate at the back of the rack, where ambient temperatures can surpass 40°C, standard relays can be short-lived.  

Metering also affects power system resiliency. It shows the power consumption and how near the system is to trip the circuit breakers, significantly if warning sirens are activated.  

Is mechanical and software integration easy?

Larger PDUs must fit into the rack's back but should not extend into the 19" space to avoid conflicting with 19" equipment. If the PDU profile is small enough, installing PDUs parallel to the 19" angles can benefit 600-wide racks.  

Most intelligent PDUs employ SNMP protocol, making DCIM or NMS integration easy. 

Will it endure throughout the data center's lifetime?

This is a nearly tricky question to answer because data center technology growth is hard to forecast! Add connectors to the PDU power distribution unit to accommodate future capacity and ensure you have spare capacity from the incoming feed.  

Modular PDUs with additional sockets may be worth investigating if your workplace constantly changes. Though more expensive, they allow socket configuration changes without affecting the IT system. 

The electrical grid restrictions and the need to reduce electricity use are permanent concerns that we must address. PDUs profile IT power demands, which you cannot increase without measuring. Elcom International offers the Power Distribution Unit.