In the UK, as in South Africa, a high number of manufacturing businesses are concerned about the impact of power blackouts on their operations. According to a Make UK survey, this is a concern for 60% of manufacturing bosses. The rise of non-linear loads in industrial environments, and the growing problem of voltage distortion, will only exacerbate these concerns. Here John Mitchell, Global Sales & Marketing Director at power quality specialist CP Automation, outlines key steps to implementing effective harmonic mitigation.
In industrial facilities, power quality influences equipment reliability, lifespan and overall productivity. Voltage distortion can wreak havoc by damaging equipment, with symptoms including voltage notching, motor vibration, arcing on bearings, nuisance tripping, electromagnetic interference (EMI/RFI) and overheating.
Despite its importance, those working in production facilities rarely monitor power quality in real time. Consequently, they are unlikely to notice any power distribution issues until they impact production.
Identifying the problem
Uneven power distribution will affect how equipment operates – some machines may be overworking and others will not operate at capacity, leading to higher energy consumption in some areas. Harmonics can also accelerate wear and tear, reducing a machine’s lifespan.
If a manufacturing team wants to add more equipment but is unaware of what is causing the capacity issues, it may turn to installing more equipment for power generation, like solar panels and generators. However, it would be more cost-effective first to survey the current power capabilities and invest in harmonic mitigation, instead.
Map the facility
A reliable power quality engineer will create a single line diagram of the factory, setting out the facility’s electrical architecture from the transformer to the individual assets.
Looking at existing power quality measures will influence the harmonic mitigation strategy. For example, historically, motors were controlled with features such as direct online (DOL) and star-delta – resulting in a demand for 7 to 16 times their full load to start – and would operate at full speed. A DOL motor with a supply voltage distortion of 8% THDV (total harmonic distortion of the voltage waveform) will be limited to 85% of its power.
To correct those motor control methods, tuned power factor correction (PFC) would typically have been installed. Upgrading to VSDs or soft starters allows for greater control of the plant processes, reduced energy consumption, and simultaneously, improved power factor, making the PFC installed unnecessary.
Power quality specialists will take measurements to understand power capacity and usage across the site. A week of monitoring gives engineers sufficient visibility into operations and the possible cause of problems.
Best practice
Reducing harmonics is key to solving any issues with power quality and distribution. The equipment used on site and severity of harmonic distortion can influence what equipment to use, such as active and/or passive harmonic filters.
Ensuring compliance with relevant industry standards and regulations will also be key to effective harmonic mitigation. Engineering Recommendation G5/5 for example, provides a set of design limits for harmonic voltage level to ensure that loads are not exceeded. It also sets out best practice on the harmonic assessment process.
Review
It is important to assess power distribution after installation of new equipment to check that the upgrade has delivered the intended result.
Facilities managers can install equipment that monitors harmonics and power quality in real time. If there is an issue or a problem in the facility that needs investigating, power quality specialists can access the monitoring equipment remotely and conduct root cause analyses.
As shown by the Make UK report, blackouts represent a significant concern for manufacturing facilities, so improving resilience, reducing costs and boosting efficiency are key. By taking the time to assess the facility, gain visibility into power distribution and implement an effective harmonic mitigation strategy, facilities can deduce the cause of their problems and maintain power quality.
CP Automation can assist clients in assessing their facilities and planning a suitable harmonic mitigation strategy.
For more information visit: www.cpaltd.net
