At a frozen food production facility in Victoria, intermittent faults across packing and inspection equipment had persisted for months without a consistent equipment-side cause. The root cause investigation included a change to the equipment supply, followed by a power quality study and monitoring that revealed an electrical environment well outside what some of the equipment required to operate reliably.
IN THIS ARTICLE
When the machine isn’t the problem
In a frozen food plant, a fault on a packing or inspection line naturally sends attention towards the machine. A failed sensor, a control board, a load cell, a component beginning to deteriorate.
At one production facility in Victoria, however, that logic was beginning to run out of answers. Multihead weighers, X-ray inspection systems, load cells and associated control electronics on one production line had been experiencing intermittent faults and reliability issues for months. Components were investigated, individual machines were checked, and replacement parts were tested.
Still, the faults returned.
“When equipment starts tripping intermittently, the natural response is to investigate the equipment,” said Dan Mitchell, Energy Solutions, Applications & Growth Strategy Manager at Hexeis. “But when different pieces of equipment on the same supply start behaving in similar ways, you have to ask whether the common denominator is somewhere else.”
The important clue came from a relatively simple test: several of the weighers were temporarily transferred onto a different electrical supply and the issues appeared to reduce.
It didn't prove the supply was responsible, but it did change the question: instead of asking what was wrong with each machine, the investigation began asking what all of those machines were being exposed to.
The numbers turn up the heat
Hexeis analysed power quality data from the affected supply and recorded its behaviour during normal production. This time, the intermittent equipment faults had an electrical pattern sitting behind them.
As production loading increased, harmonic distortion rose with it. At the same time, the supply voltage reduced under the heavier loading.
For conventional plant equipment, those conditions may not immediately result in an obvious failure; sensitive electronic equipment can be less forgiving.
The monitoring recorded:
- Voltage harmonic distortion (THDv): 7.5–8.5%, exceeding 8.5% at times.
- Current harmonic distortion (THDi): 11–12%, with a recorded peak of 12.8%.
- Production current: more than 1,200 A per phase under higher loading.
- Power factor: 0.91
- Reactive demand: typically around 300–370 kVAr.
- Supply voltage: reducing to 223.3 V under higher plant loading.
No single number told the whole story; what mattered was how the electrical conditions changed together. As production demand increased, the measurements showed harmonic distortion rising while voltage fell. The investigation identified harmonic distortion on the plant’s shared electrical supply as the principal power quality concern.
Why power factor correction alone wouldn't solve it
While a power factor of 0.91 immediately gives an electrical engineer something to investigate, it was not the main issue Hexeis identified.
“You can look at a power factor of 0.91 and immediately think, ‘we need power factor correction’”, Mitchell said. “But if harmonics are driving the reliability issue, correcting power factor alone doesn’t solve it. You have to separate the different effects and engineer for the problem that’s actually there.”
The investigation pointed to harmonic distortion as the primary issue, alongside reactive power and voltage variation. Installing a conventional power factor correction unit alone would therefore have addressed only part of the electrical behaviour being observed.
Hexeis instead developed a modular power quality solution around the way the plant load was actually behaving. The design combined two technologies:
- An active harmonic filter (AHF) to reduce harmonic distortion as plant conditions changed.
- A static VAR generator (SVG) to improve power factor and reduce reactive current.
The system was designed for installation at the main switchboard (MSB), treating the whole shared supply rather than individual machines. Because production loads vary throughout the day, Hexeis also allowed additional filtering capacity rather than sizing the system only to the monitoring snapshot.
Post-installation monitoring was also recommended to confirm performance under normal production conditions and identify whether any particularly sensitive equipment needed further voltage conditioning.
The proof is in the modelling – for now
Diagnosis was only one part of the exercise. The plant also needed to understand what the proposed solution was expected to change before deciding whether to proceed.
Using the power quality measurements collected during the investigation, Hexeis modelled the anticipated electrical performance of the proposed AHF and SVG solution.
Note: These figures are modelled results based on the collected power quality data, not yet a validated before-and-after – that confirmation comes from post-installation monitoring.
| Measure | Before | After |
|---|---|---|
| THDi | ~11–12% | ~2–3% |
| THDv | ~8.1–8.6% | ~3–4% |
| Power factor | ~0.91 | ~0.99 |
| Reactive power | ~370 kVAr | ~114 kVAr |
| Apparent power | ~881 kVA | ~808 kVA |
| Current at 415V | ~1,226 A | ~1,124 A |
The modelling suggests the proposed solution will deliver:
- Voltage distortion reduced from more than 8% to around 3–4%, bringing the supply below the level required by the affected equipment.
- Approximately 100 A less current through the system, while maintaining the same productive load.
In practical terms, that means a cleaner, more stable power supply, less strain on the electrical system and better operating conditions for the packing, weighing and inspection equipment.
“The modelling gives the client something tangible to make the decision against, but we’re very deliberate about calling it modelling,” Mitchell said. “The real test comes after installation, when the monitoring goes back on and we can see what the system is doing under normal production conditions.”
A design can be modelled against measured data, but the ultimate measure of success is what happens when the plant returns to full production.
Before you replace another part…
The turning point in this investigation came when the team stopped looking at each fault in isolation and started looking at what the affected equipment had in common.
When multiple sensitive loads on the same supply begin faulting intermittently, the supply itself deserves closer attention.
In this case, a temporary change of supply to another circuit provided a practical back-to-back assessment to rule out equipment faults. Then power quality monitoring gathered the detailed data to show what that equipment was exposed to under real production conditions, rounding out the investigation with actionable information.
“If the fault keeps coming back and the machine keeps checking out, stop replacing parts and start measuring the supply,” Mitchell said.
If sensitive equipment on your line keeps faulting without a clear cause, a power quality assessment can be your next step.
Frequently asked questions
Can harmonic distortion cause equipment to fault?
Yes. Sensitive electronic equipment can be affected when harmonic distortion changes the quality of the electrical supply beyond the conditions it is designed to tolerate. At this frozen food plant, voltage harmonic distortion was recorded at approximately 7.5–8.5%, while the affected equipment required an environment below approximately 5%.
How do you know if equipment faults are being caused by power quality?
Recurring faults across different machines on the same electrical supply can be a reason to investigate upstream. In this case, temporarily moving several weighers to another supply reduced the incidence of faults. Power quality monitoring was then used to measure what the equipment was experiencing during production.
Will power factor correction fix harmonic distortion?
Not necessarily. Power factor correction and harmonic filtering address different electrical issues. At this site, power factor was approximately 0.91, but harmonic distortion was identified as the primary concern. Correcting the power factor alone would not have addressed the main issue.
How can harmonic distortion be reduced in a manufacturing plant?
The appropriate solution depends on the electrical system and the loads connected to it. For this facility, Hexeis proposed an active harmonic filter to reduce harmonic distortion, combined with a static VAR generator to improve power factor and reduce reactive current.