Power quality describes how well the electricity supplied to a site suits the equipment connected to it. When voltage, waveform or load balance drift outside acceptable limits, the effects include nuisance tripping, equipment that fails earlier than expected, overheating cables and transformers, unplanned downtime and higher energy costs. Many of these problems are transient or go undetected, which makes them difficult to trace without measuring the supply.
A power quality audit does that measuring. This article explains what NPS technicians measure and find, with examples from our own case studies, the signs that point to a problem, and why an audit works best alongside regular maintenance by qualified professionals.
What a Power Quality Audit Measures
An on-site audit by qualified technicians logs how your power behaves over time, including:
- Supply voltage, and any sags, swells and transients
- Harmonic distortion on both voltage and current
- Load profile and demand across the logging period
- Line and phase balance
- Power factor and reactive power
- Earthing, polarity and neutral integrity
- Wiring, terminations and circuit loading
How the Audit Works
NPS connects calibrated power quality analysers at your switchboard or distribution boards and logs voltage, current, harmonics and power factor over a representative period, typically around a week, so that both normal and peak conditions are captured. Technicians then analyse the data against the relevant Australian standards and equipment limits to isolate the cause of any problem. You receive a detailed written report that explains what was found, the likely cause, the risk to your equipment and the practical steps to fix it.
What Power Quality Audits Find
Voltage Disturbances: Sags, Swells and Transients
Transient and undetected disturbances can cause unexpected and irreversible damage to sensitive equipment, as well as unplanned downtime. At Amcor, irregular power supply and surges had caused extensive damage to a printing plant valued at $5 million, along with expensive production downtime. NPS installed parallel redundant three-phase 80kVA UPS systems, with a maintenance bypass switch and a surge diverter on the incoming mains. For more on protecting a site from surges, see lightning and surge protection.
Harmonic Distortion
Harmonics are unwanted frequencies on your power, caused by equipment such as variable speed drives, UPS systems and LED lighting. High harmonics overheat cables, transformers and motors, waste energy and can trip protection, which is why an audit measures them on both voltage and current.
Overloaded Circuits, Poor Balance and Weak Earthing
NPS audits look for overloaded circuits and unbalanced loads, and check earthing, polarity, neutral integrity, wiring and terminations. Logging the load profile across the whole period shows when each problem occurs, not only whether it exists.
Equipment and Records That Do Not Match the Site
A power audit also looks at the equipment protecting the site, including undersized or ageing UPS units. When NPS carried out an asset audit for a customer in Sydney, to AS/NZS 3598.1 to 3598.3, the team found an additional UPS unit that was not on the client’s records. NPS matched the serial numbers, confirmed where each system was installed and delivered a verified asset list with a report of findings and recommendations. Read the full asset audit case study.
Problems Found Before the Equipment Goes In
An audit is not only for fixing problems after the fact. When Melbourne Pathology rolled out new Abbott Alinity diagnostic machines across regional Victoria, the project began with a power quality assessment. That meant the power protection design was right from the start, avoiding the rework and delays that come from retrofitting after the equipment is installed.
Signs You Need a Power Quality Audit
- Nuisance tripping of breakers or RCDs
- Equipment failing earlier than expected
- Transformers, cables or motors running hot
- Flickering lights or display flicker
- A UPS that frequently switches to battery
- Unexplained downtime or data loss
- High energy bills or power factor penalties
- Before and after installing major new equipment
Why an Audit Works Best With Regular Maintenance
An audit gives you a clear picture of how your power behaves and a plan to fix what it finds. Power conditions change as equipment is added and protection equipment ages, so an audit is one part of keeping a site reliable. UPS preventative maintenance covers the other part, which is the condition of the equipment itself. Every NPS visit includes battery health testing and voltage checks, load testing to verify capacity and transfer times, thermal imaging to detect hotspots, firmware updates where applicable and an environmental assessment, followed by a detailed report with findings and recommendations.
The two work well together. NPS maintains the UPS and surge diverter installed at Amcor under a preventative maintenance contract, and the Socomec 60kVA UPS and battery cabinet at the Skin Health Institute are under a preventative maintenance contract too. NPS offers Comprehensive and Standard preventative maintenance contracts, with a 24/7 service hotline and rapid breakdown response.
Batteries and the room they sit in deserve particular attention. Read how NPS technicians found severely degraded batteries at a transport site, why UPS systems and dust do not mix, and how computer room cooling protects power protection systems. NPS also provides a full battery maintenance and replacement service.
What You Can Check Yourself, and What Needs a Professional
Worth Doing Yourself
- Keep a log of nuisance tripping, equipment failures and UPS battery events, with the date and time of each
- Note hot cables or transformers and flickering lights, and where they occur
- Keep an up-to-date record of every UPS and protection device, including serial numbers and installation dates
- Keep equipment rooms cool and vents free of dust
Leave to a Professional
- Power quality logging with calibrated analysers, and analysis against Australian standards
- Harmonic and load analysis
- Checks of earthing, polarity and neutral integrity
- Battery testing, load testing and thermal imaging
- Safe battery removal and certified disposal, because batteries are regulated waste
Frequently Asked Questions About Power Quality Audits and Maintenance
What problems does a power quality audit find?
It finds voltage sags, swells and transients, harmonic distortion, unbalanced phases, poor power factor, overloaded circuits, and weaknesses in earthing, polarity and neutral connections. NPS audits also look for undersized or ageing UPS units.
Can poor power quality damage equipment?
Yes. Transient and undetected power quality problems can cause unexpected and irreversible damage to sensitive equipment, unplanned downtime and higher energy costs. Common signs include nuisance tripping, equipment failing early and a UPS that often switches to battery.
What is the difference between an asset audit and a power quality audit?
An asset audit records what power protection equipment is installed and where, so your records are accurate and ready for servicing. A power quality audit measures the electrical supply itself, including voltage, harmonics and power factor, to find disturbances that damage equipment or cause downtime.
If I have had a power quality audit, do I still need maintenance?
Yes. An audit measures the quality of your supply and gives you a plan to fix problems. Preventative maintenance checks the condition of the equipment, including battery health, load capacity, hotspots and firmware, and gives you a written report after each visit.
Can I carry out a power quality audit myself?
An audit needs calibrated power quality analysers connected at your switchboard or distribution boards, and the logged data has to be analysed against Australian standards and equipment limits, so it is work for qualified technicians. You can help by keeping a log of tripping, failures and UPS battery events, and by keeping your equipment records up to date.
What happens after the audit?
NPS delivers a detailed written report with the findings, the likely cause and clear recommendations. We then work with you to carry out any remediation, from harmonic filtering and power factor correction through to surge protection and UPS systems.
Does NPS audit and service equipment from other manufacturers?
Yes. NPS audits are vendor-independent, and NPS maintenance is vendor agnostic, covering most UPS systems regardless of manufacturer, including APC by Schneider Electric, Eaton, Socomec and Vertiv.
Talk to NPS About a Power Quality Audit
For over 30 years NPS has provided power protection to commercial and industrial sites across Australia and New Zealand, with offices in Sydney, Melbourne, Brisbane and Perth. Because NPS also delivers UPS systems, surge protection and turnkey power solutions, we can carry the work from diagnosis through to remediation. To find out more about the NPS power quality audit service, or to talk through the symptoms on your site, contact the NPS team.