[ Solution ]
Power Quality Monitoring
Power quality cannot be managed unless it is measured. Reactive charges stay invisible until they land on the statement, harmonic distortion until it burns a motor — yet both were measurable weeks earlier.
The three costs of poor power quality
Power quality sounds like an abstract engineering topic. It is not — it takes money from three places:
Reactive charges. Once power factor drops below the threshold, excess reactive units are charged on the distribution statement. At most sites this line has been paid for months and nobody has asked where it comes from.
Failure risk. Harmonic distortion and phase imbalance stress equipment continuously. Overheating switchboards, failed power-factor-correction capacitors, drives tripping without explanation — all grow from the same root.
Shortened life. Motors and transformers running under distortion age early. That invoice arrives not today, but three years from now.
Your network’s health report
Four indicators are watched continuously; the moment a limit is crossed, a notification goes out.
Power Factor
99.1%
Cos φ · Good
Current Imbalance
6.2%
Unbalance · Review
Current Harmonics
12.3%
THDi · Review
Voltage Harmonics
1.6%
THDu · Good
All four do not have to be good at once — what matters is which one is moving, and in which direction. Voltage harmonics come from the network; current harmonics come from your own load. Until the two are separated, responsibility cannot be separated either.
Six axes, one score
Four indicators make a table that is hard to read at a glance. We fold them into six axes and a single quality score — month-on-month comparison and ranking across sites both run on this number.
Power Quality Score
period average- Cos φ 99.1% 99/100
- THDi 12.3% 61/100
- THDv 1.6% 96/100
- Unbal. 6.2% 62/100
- Inductive 13.5% 66/100
- Capacitive 1.5% 96/100
The score’s job is not to produce one number but to show which axis is falling behind. In the example above, power factor and voltage harmonics are close to perfect; current harmonics and imbalance are the two axes pulling the score down. The investment decision is made by looking at those two.
Which machine is the source of the distortion?
At site level, “current THD 12.3%” gives no address. The panel breaks it down per device and ranks by THDi:
| Device | Cos φ | Inductive | Capacitive | THDi | Status |
|---|---|---|---|---|---|
| ZAT-2 | 64.5% | 189.6% | 2.2% | 16.2% | Critical |
| TX-2 | 97.4% | 2.7% | 4.0% | 14.0% | Watch |
| TX-4 | 98.5% | 14.4% | 0.2% | 10.7% | Watch |
| TX-1 | 99.4% | 2.2% | 1.1% | 9.2% | Watch |
| Cooling Tower | 46.6% | 69.9% | 0% | 1.2% | Critical |
| PSP | 48.0% | 0% | 50.7% | 1.9% | Critical |
Taken from a working site; device names are site-specific.
The table shows two different problems on one screen. ZAT-2 has low power factor and runaway inductive consumption — a power-factor-correction problem. PSP is the opposite, on the capacitive side: the capacitors stayed switched in while the night load dropped. Both are “quality problems”, but their fixes are opposites.
Without the ranking, the maintenance team sweeps the whole site. With it, they go to the first two rows.
Which hour does the charge risk come from?
Reactive charges are billed on period totals, but they are born from hourly behaviour. Without seeing which shift and which hour approaches the threshold, nothing can be corrected.
Reactive Consumption Heatmap
InductiveCapacitiveThe map shows a pattern: the problem is not constant, it is shift-dependent. That points to a correction panel stuck on a fixed stage. The fix is not buying new capacitors but retuning the existing stages to the load profile — at almost zero cost.
The same map is produced for harmonic distortion. There the pattern is usually reversed: high overnight and in the early morning, moderate by day. The cause is usually the handful of drives left running overnight.
What we measure, and from where
Measurement provenance
- Voltage
- V
- L-L and L-N · per phase · upper/lower limit tracking
- Current
- A
- L1, L2, L3 separately · imbalance derived
- Power factor
- Cos φ
- Main meter · from period reactive energy
- Harmonics
- THDi · THDu
- Analyser · current and voltage separately
- Reactive
- kvarh
- Import and export metered separately
- Demand
- kW
- Half-hourly · against agreed capacity
- Frequency
- Hz
- Network side
Measurements come from your existing power analysers. If an analyser capable of quality measurement is already installed, no hardware needs replacing; if not, we agree before installation which points need what.
Capacity: the second source of charges
Alongside reactive charges, a second line is watched together with quality: maximum demand against agreed capacity. Every half-hour that exceeds your agreed capacity (kVA) is billed as excess capacity charges — and since DCP161, at penal rates.
The subtlety is that the excess is measured on the half-hourly average, not the instantaneous peak. A short inrush does not trigger it; a half-hour of overlapping loads does. The panel computes this average continuously and warns as you approach the agreed capacity — before it is exceeded.
Utilisation is watched too. If your peak demand sits far below the agreed capacity, you are paying for capacity you never use; reducing the agreed capacity is a direct saving. That is a negotiation you cannot have without measurement.
Frequently asked
We have power-factor correction and no reactive charges. Do we need this module?
The correction panel may be sufficient today. Capacitors age, stage contactors stick, the load profile changes — the charges usually start suddenly, one day. The module's job is to show the trend of power factor without waiting for the charge. And reactive is only one dimension of quality: harmonics and imbalance are not fixed by correction capacitors.
Do harmonics need special hardware to measure?
A power analyser that measures THD. Some analysers in the field already do; others only report basic electrical values. We review your existing device list and tell you which are sufficient and which points need an additional device — replacing everything is unnecessary; the main incomer and a few critical boards are usually enough.
If voltage harmonics are high, is it our fault?
Usually not. Current harmonics are born from your load; voltage harmonics come from the network and carry the loads of neighbouring sites too. Because the panel measures the two separately, that distinction can be made. For a voltage-harmonics problem the counterparty is the DNO — and your measurement record is the basis of that conversation.
How is the quality score calculated?
Six axes — power factor, current THD, voltage THD, imbalance, inductive and capacitive ratio — are each scored 0-100 against their own limits, then averaged with weights. Weights and limits are adjustable per site; the defaults rest on published standards. The score's formula is written openly in the panel; it is not a black box.
Is the data in the screenshots real?
The device ranking table is taken from a working site; the device names are that site's own. The heatmap and the quality score are drawn with sample values — publishing a real site's day-by-day reactive profile would expose its production schedule.
Let us measure what is happening on your site.
In a one-hour call we look at your existing setup and set out exactly which measurement points are needed and what you would be able to see.