HM Prison Service - Cardiff Prison

Cardiff Prison – powerPerfected

HMP Cardiff is a category B Local/Training Prison, holding male adult prisoners drawn predominantly from the surrounding court catchment area in South East Wales. The three Victorian wings have had major refurbishment and the prison’s capacity was extended in 1996 with three new wings.

The challenge, the solution and the savings

The prison’s electrical load includes lighting circuits, heating and ventilation systems, and switch mode power supply devices. Of obvious importance are the electronically controlled security systems installed at the site. After evaluation, a 560kVA/800A powerPerfector unit was installed in 2006 with an 8% optimisation setting. See figures 1 and 2 for a before and after comparison.

Topline results

We were delighted that the savings of between 12.5% and 16.6% in kWh consumption were above those we predicted in the business case. The reduction in Maximum Demand of 16.9% will really help to keep the site’s demand below the available capacity and also make for a reduction in capacity charges. Also, the site’s equipment is running more efficiently as a result of improved phase balancing, reduced harmonics and optimised voltage. Equipment lifecycles will be extended too, giving valuable savings in the future. To install the powerPerfector unit, the site was run from a standby generator during the 8 hours of downtime, so there was no interruption to the daily routine – particularly important for a prison of course. Following installation all electrical equipment has operated normally and there are no reports of any problems.

Voltage Power Optimisation. The less obvious benefits

Reduced maintenance, longer life
All electrical equipment has an optimum voltage at which it works best. A powerPerfected supply delivers that optimum and reduces the strain on your electrical equipment, leaving it to work more reliably and for longer.

Better quality power supply
Some things you may have accepted for years as product faults can turn out to be caused by a poor quality power supply. For instance, the life of incandescent light bulbs is almost doubled when the supply voltage is optimised. Now imagine that in relation to an IT network or an expensive piece of manufacturing equipment.

Missing the penalty kick
Power factor penalty charges – which are now uncapped in the UK – can be avoided if your power factor is above 0.95. If your power factor is at around 0.9 at the moment, powerPerfector could remove your exposure to these charges by improving the electrical efficiency of your site.

Lower harmonic distortion and reduced neutral currents
powerPerfectors are able to filter harmonics on the mains incomer. Harmonic distortion is on the increase and can lead to random failures of electronic equipment – particularly computers.

Protection
Common transients – very brief spikes in voltage from the grid – are eliminated by powerPerfector. Transients at this level can cause catastrophic damage to equipment, but smaller, more common transient events will also shorten the life expectancy of electrical equipment over time.