Dynamic Power Variations in Data Centres and Network Rooms
The power requirement required by data centres and network rooms varies on a minute by minute basis depending on the computational load. This magnitude of this variation has grown and continues to grow dramatically with the deployment of power management technologies in servers and communication equipment. This variation gives rise to new problems relating to availability and management.

Performing Effective MTBF Comparisons for Data Centre Infrastructure
Mean Time Between Failure (MTBF) is often proposed as a key decision making criterion when comparing data center infrastructure systems. Misleading values are often provided by vendors, leaving the user incapable of making a meaningful comparison. When the variables and assumptions behind the numbers are unknown or are misinterpreted, bad decisions are inevitable. This paper explains how MTBF can be effectively used as one of several factors for specification and selection of systems, by making the assumptions explicit.

Comparing Availability of Various Rack Power Redundancy Configurations
Transfer switches and dual-path power distribution to IT equipment are used to enhance the availability of computing systems. Statistical availability analysis techniques suggest large differences in availability are expected between the various methods commonly employed. This paper examines various electrical architectures for redundancy that are implemented in today’s mission-critical environments. The availability analyses of these various scenarios are then performed and the results are presented. The analysis identifies which approach provides the best overall performance, and how alternatives compare in performance and value.

Hazards of Harmonics and Neutral Overloads
This document provides an overview of problems related to harmonic currents, with a specific focus on Information Technology equipment. The way that international regulations solved these problems is described.

Mean Time Between Failure: Explanation and Standards
Mean Time Between Failure is a reliability term used loosely throughout many industries and has become widely abused in some. Over the years the original meaning of this term has been altered which has led to confusion and cynicism. MTBF is largely based on assumptions and definition of failure and attention to these details are paramount to proper interpretation. This paper explains the underlying complexities and misconceptions of MTBF and the methods available for estimating it.

Powering Single-Corded Equipment in a Dual Path Environment
The use of dual power path architecture in combination with IT equipment with dual power supplies and power cords is an industry best-practice. In facilities using this approach there are inevitably some IT devices which have only a single power cord. There are a number of options for integrating single-corded devices into a high availability dual path data center. This paper explains the differences between the various options and provides a guide to selecting the appropriate approach.

Reliability Models for Electric Power Systems
This note explains the sources of downtime in Electric Power Systems and provides an explanation for site-to-site variations in Power Availability. The the factors affecting power quality from generation to the utilization point are summarized. There is a qualitative description of a model which can be combined with data to provide a method for estimating down time based on site-related factors.

Understanding Power Factor, Crest Factor, and Surge Factor
This White paper explains the technical terms of Power Factor, Crest Factor, and Surge Factor. The use of these terms in specifying UPS is explained.