Power Quality (PQ) related issues present a significant challenge to those responsible for the management of electrical networks and Data Centre facilities. The widespread use of and increasing dependence upon electronic equipment - such as information technology equipment, power electronics including programmable logic controllers (PLC) and energy-efficient lighting - have led to a complete transformation in the nature of electrical loads. These loads are both the major root causes of - and the major casualties of - power quality problems. Due to their non-linearity, all these loads cause disturbances in the voltage waveform.
Along with advances in technology, the organization of the worldwide economy has evolved towards globalization and the profit margins of many activities has seen a tendency to decrease. The increased sensitivity of the vast majority of processes (industrial, services and even residential) to PQ problems means that the availability of high quality electric power is a crucial factor in terms of developing competitive advantage across every market sector.
It’s widely understood that mission-critical facilities must run continuously, and, of course, that any power interruption, even for a short time, can disrupt business operations and result in significant financial losses.
Although today’s Data Centres are all designed with a high level of inherent redundancy in order to minimize downtime, just as important as the mission-critical applications themselves, however, is the quality of the supplied power. In order to achieve the delivery of consistent, high quality power, it is vital to understand the nature of PQ disturbances and their causes.
There are several major categories of power quality disturbances, detailed below:
Disturbance type Wave form Possible causes Consequences
Voltage sag/dip Faults on the transmission, in distribution network, or in consumer’s installation. Start-up loads. Malfunction of IT equipment, safety systems, or lighting. Loss of data. System shutdown.
Voltage interruption Mainly due to opening and automatic re-closure of protection devices to decommission a network faulty section. The main fault causes are insulation failure, lightning and insulator flashover. Tripping of protection devices, loss of information and malfunction of data processing equipment.
Voltage spike/transient Lightning, ESD, switching of lines or power factor correction capacitors, utility fault clearing. Destruction of electronic components, data processing errors or data loss.
Voltage swell Atmospheric, swells are due to lightning; Transient, swells are due to insulation faults between phase and earth or rupture of neutral conductor; Switching, swells are due to opening of protection devices, generated by energizing capacitor banks or caused by variations in inductive current. Data loss, flickering of lighting and screens, stop or damage of sensitive equipment.
Harmonic distortion Modern sources like all non-linear loads, such as power electronics equipment including ASDs, switched mode power supplies, data processing equipment, high efficiency lighting. Increased probability in occurrence of resonance, neutral overload in 3-phase systems, overheating of all cables and equipment, loss of efficiency in electric machines, electromagnetic interference with communication systems, errors in measures when using average reading meters, nuisance tripping of thermal protections.
Voltage fluctuation Transmitters (radio), faulty equipment, ineffective grounding, proximity to EMI/RFI source. Most consequences are common to under-voltages. System halts, data loss.The most visible consequence is the flickering of lighting and screens.
Noise Transmitters (radio), faulty equipment, ineffective grounding, proximity to EMI/RFI source. Disturbances on sensitive electronic equipment, usually not destructive. May cause data loss and data processing errors.
The costs of PQ problems are highly dependent upon several factors, mainly the type of business activity. Other factors, such as the sensitivity of the equipment used within the facilities and external market conditions, for example, also influence the costs incurred. They can be divided into:
Direct costs that can be directly attributed to the disturbance. These costs include the damage to the equipment itself, production downtime, raw material losses, salary costs during non-productive period as well as restart costs, and financial penalties such as consequentials incurred through the non-fulfilment of contractual obligations. Sometimes, during the non-productive period, some savings are achieved, such as energy savings, which must be subtracted from the costs incurred in order to achieve a balanced view. Some disturbances do not necessarily result in a production stoppage, but may have other associated costs such as a reduction in equipment efficiency and useful equipment lifetime.
Indirect costs are very hard to evaluate and will depend upon the specific circumstances within a particular business at any given time. For instance, a business may fail to meet delivery deadlines as a result of disturbances and the resulting downtime – this may affect future orders and could ultimately affect market share and even brand equity. Whilst investments in the prevention of PQ problems may also be considered an indirect cost, this may be dwarfed by the potential indirect costs associated with PQ problems themselves.
Numerous studies have been carried out to evaluate the costs of PQ problems for consumers. The assessment of a realistic value is nearly impossible, so they are all based on estimates, but all point to a common factor, that PQ costs are enormous:
- 30,000 industrial customers are affected by PQ problems every day.
- PQ annual costs were estimated at 150-200 B€ in Europe, with the same value for USA.
- Downtime costs associated with mission-critical facilities are estimated to range from 70 k€ (flight booking) to 5M€ (trading activities) per hour.
Thanks to developments in technology and the software now available, a PQ meter is a highly-effective means to detect, solve, and even prevent problems on both utility and customer power systems. Not only can a monitoring system provide information about system disturbances and their possible causes, it can also detect problem conditions throughout the system before they cause customer complaints, equipment malfunctions, and even equipment damage or failure. Power quality problems are not necessarily limited to the utility side of the system - indeed, surveys have shown that the majority of power quality problems are localized within customer facilities.
PQ meters are powerful multi-function network analysers; they actively contribute to the optimisation of an electrical network’s operation. To ensure these aims are achieved, PQ meters allow the following functions:
• Measurement of all electrical values and temperatures
• Management of energy and allocation of other fluids (water, gas)
• Monitoring of all parameters that might influence quality of the supplied power
• Control/command of remote devices
• Recording network events and their waveforms in case of disturbances (dip, swell, harmonics…) or failures, and providing complete diagnostic of power quality supply (EN50160 report)
• Communication with other equipment and the transmission of information (supervision, BMS…) via an RS485, Ethernet or USB connection.
PQ meters apply the latest IEC power quality standards, and provide a wealth of useful information on electrical network events, helping you pinpoint the source of potential problems, but they can do even more:
Improve power quality and reliability
· The early detection, identification and location of the cause of power quality-related problems that could result in equipment or process downtime.
· Proactive assistance in corrective/preventive maintenance, helping to reduce costs.
· Verify compliance with PQ standards (EN50160, IEC 6100-4-30, IEC 61557-12).
· Verify that PQ complies with energy supplier contract.
Optimize equipment use
· Extend asset lifetime by measuring and reducing network disturbances.
· Ensure equipment performance and the optimization of installation power capacity.
Measure and control energy costs
· Allocate or sub-bill energy costs to departments, uses, or clients.
· Identify losses and inefficiencies to help reduce energy consumption.
· Verify savings that result from equipment upgrades, energy efficiency programs.
· Analyse network pollution in order to reduce electricity bills by avoiding penalties
The availability of high quality power is obviously crucial for running data centres - particularly in order to avoid huge financial and commercial losses related to power quality issues and their impact on a business.
The presence of polluting devices in the electrical network often distorts the supply voltage and under polluted conditions, customer’s devices behave differently than under ‘normal’ sinusoidal voltage conditions.
Power quality issues can have extremely harmful effects on the integrity and reliability of an electrical network. With the correct diagnosis, however, today’s Data Centre managers can proactively mitigate – and in many cases completely remove – the effects of the disturbance.
A high performing power quality meter is the ideal choice when continuous monitoring is required. Not only will it monitor and meter all electrical parameters, but it will also enable the accurate management of energy consumption. By monitoring PQ parameters – both the detection and identification of network disturbances – a Data Centre’s availability and efficiency can be optimised.
