Where a site suffers from widely fluctuating voltages, supply disturbances, or harmonics, these can all lead to premature equipment failure. Somewhat conversely, in the drive to modernise, introduce renewables and make sweeping energy savings, various solutions and technical advances have worsened the overall power quality in the UK.
Working within the limits
Harmonic related problems can originate from a number of causes, both on and off site, including the increased use of equipment such as switch mode power supplies, other high speed switching devices, plus the increased prevalence of renewables. Whilst regulations such as G59 and G5/4 exist to handle things on the larger scale, many sites are not even aware of the details, the implications of not working within their limits and risks stemming from failing to adhere. Greater uptake of demand side response (DSR) and storage, with associated control and switching could exacerbate this issue.
While these problems in themselves do not impact directly on site energy consumption, their effects will certainly be felt on the bottom line through either unplanned process stoppages or premature equipment failure. It is important to identify the cause, and implement a remedial course of action.
Identifying causes and taking action
The first step is to quantify the problem and ask yourself if there’s anything unusual happening: Is plant failing?
By way of example, one of our clients had observed unusually high equipment failure rates. After power logging we identified that the site suffers repeated yet extremely short duration power interruptions with spikes in voltage over ten times the rated level, directly leading to equipment failures. It was eventually determined that this is related to the external supply and is currently in the hands of the regional DNO for comment.
Simple surge protection could relieve the problem, although there may also be harmonic issues, identified through an in-depth survey. Mitigation of harmonics, or at least preventing propagation around the site, is a specialist task, requiring active filtration tuned to the exact frequencies. It is often claimed that a simple choke device will prevent such issues, however, this is for a single frequency and amplitude and is limited in its prevention capability.
Addressing power factor
If the power factor, a measure of electrical efficiency, is below a level of 0.95, penalty charges are applied to the bill. A poor power factor will directly increase the site demand, resulting in higher charges and current loads. An apparent need for a larger supply can be prevented with the installation or upgrade of power factor correction (PFC).
Consideration should always be given to the installation of de-Tuned PFC, with harmonic resistant filters a key feature.
Voltage optimisation solutions
From small devices inside almost every electrical instrument in use, to large scale control in power plants, unseen voltage management impacts on our everyday lives. If we take into account the increase in renewable energy supplies and subsequent variation in power sources, it becomes apparent that there is a need to control the supply we are receiving, particularly if we need a stable input for a particular process. Where power is fed from renewable sources, the voltage can be some 5% higher than the grid. Much modern equipment is extremely susceptible to high and/or fluctuating voltages. Gaining control is vital, and can reduce energy consumption as part of the equation.
Shades of grey
It’s hopefully clear from the information above, that none of this is black and white. It isn’t always apparent until we’ve done a survey and discussed things in detail that the real issue comes to light. Solutions turn out to be different to ideas. Many engineers and energy managers will relate to this, often resulting in inertia and no progress due to an overload of considerations.
Efficient Power Solutions is able to offer a complete range of energy surveys, energy monitoring and power quality surveys, all backed up by comprehensive reports, to allow us to advise on the best fit solution for your requirements.