Power Quality Survey
To compliment our data centre planned preventative maintenance services Workspace Technology recommends an annual Power Quality Survey.
Workspace Technology offers a comprehensive Power Quality Survey service which is designed to help:-
- Identify and quantify harmonic related problems
- To investigate ‘flicker’, ‘sag’ and other phenomena
- Confirm electricity supply voltage levels
- To identify Power Factor levels
- Check loads before planned changes to distribution
- To record the data needed to assess G5/4-1 compliance
Depending on the specific site requirements a ‘snapshot’ survey can be completed. Other circumstances may require recording equipment to be left in place for a week or more.
Power Quality Survey reports provide customers with a clearly laid out summary of load, power factor and harmonic data findings. When quality issues are identified the report will include recommendations to correct problems.
The implementation of survey recommendations will help customers reduce energy bills and can prolong life and prevent premature failure of equipment.
Minimum recommended frequency: Yearly, or following any major infrastructure changes
Electrical Quality Technical Overview
Harmonics is a term that is used to describe both electrical voltage and current distortion. Distortion is caused by loads drawing their current through semiconductors which have a ‘non-linear’ characteristic.
Examples of non-linear loads include:- servers, network equipment, high-frequency lighting, switch-mode power supplies, variable-speed drives, Uninterruptible Power Supplies and three phase rectifiers. All of this equipment is present within data centre environments.
Why are harmonics a problem
Harmonic Current causes overheating of conductors and their insulation, overheating of transformers with increased losses, overloaded Neutral conductors, Neutral to Earth potential, overheating of capacitors and ultimately premature ageing or failure of equipment. Additionally, exporting excessive harmonic distortion to the supply networks may well fall foul of the enforced requirements of G5/4-1.
Harmonic Voltage – causes linear loads to draw non-linear current resulting in current distortion effects, torque pulsation in motors, capacitor dielectric failure, insulation breakdown, server and network equipment power supply failure, electronic lighting failure, malfunction of sensitive electronic equipment and, again, excessive distortion in distribution supply networks.
An understanding of Harmonic distortion levels will enable Workspace Technology to make recommendations for appropriate corrective actions.
Power Factor (p.f.) of a circuit is the ratio of useful power (kW) against apparent power (kVA). It is a measure of how efficiently the electrical supply is being utilized. The lower the p.f., the greater the energy efficiency of the system.
Low Power Factors can incur penalties from electricity supply companies. Additionally poor Power Factor increases power system costs in the following ways:
The data centre consumes more power
System charges passed on by the electricity supplier increase
Reduces the life of connected equipment
A understanding of the data centre Power Factor will enable Workspace Technology to make recommendations on corrective actions.
A sag or swell is a decrease or increase in the rms value of the voltage ranging from a half cycle to a few seconds. The largest cause of problems from the utility side is voltage sags. Sags or swells can occur within a plant at the point of use and may be unrelated to the quality of power at the service entrance. These types of disturbances can lead to problems with data centre equipment that is unprotected by UPS equipment.
An understanding of voltage quality will provide supportive information for any ongoing reviews with the electricity supplier.
Typically the actual supply voltage received in the UK will vary between 207V and 253V. The optimum voltage for your electrical equipment is 220V. The identification of voltage levels will determine if your site would benefit from the deployment of voltage optimisation energy saving equipment.
G5/4 is a harmonic regulation to ensure that levels of harmonic current in the public electricity supply system do not give rise to problems for connected users.
Where the G5/4 recommended voltage distortion levels are exceeded, the electricity supplier will require mitigation measures.
Survey Schedule of Works
- Agree point of connection for analyser equipment. To ensure G5/4 compliance, measurements must be taken at the “Point of Common Coupling”.
- Install recording equipment. Measurements are normally taken over a seven day period to cover peak distortion periods (Saturday & Sunday evening), unless the process will not operate over these periods.
- Disconnect recording equipment.
- Download information and produce analysis report based on recorded findings
- Produced formal Electrical Quality Report.