In modern times, the supply of electrical energy is crucial for everybody, including businesses, households, medical facilities, and datacentres. It isn’t just availability that’s important, but also getting the best quality supply to your facility. Power supply companies, power grid operators and municipal utilities have a duty to ensure the reliable and seamless operation of power grids. Damage must be prevented within their network but above all, in customer installations.
Thus, power supply companies have a responsibility to:
- Ensure power supply is guaranteed without disruption.
- Ensure the best possible quality of power supply across their network.
- Prevent failure in their grid or damage to the customer’s installations.
- And to comply to the relevant power quality standards.
This task of supplying good quality power is also becoming increasingly difficult as grids begin consisting of multiple decentralised modern renewable energy sources. The supply of power by means of solar photovoltaics or wind turbines are subject to daily and seasonal fluctuations in weather conditions which often has an impact on the grid or local supply system.
Furthermore, it also becomes difficult for the power company to supply the highest level of power quality if the load demand puts strain on the supply system i.e., inductive loads by means of large motors, etc. Fluctuating consumption can also damage supply sources and lead to problems on the consumer’s side. Heavier irregular loads, for example heat pumps or charging systems for electrical vehicles, contribute to the change from typically more constant power loads.
The increased use of sensitive electronics also brings with it new requirements. Digitalisation, Industry 4.0, smart homes and the Internet of Things enlarge the proportion of electronic systems in the power grid, in commercial and industrial installations, and in the private residential sector. These electronics react especially sensitively to the slightest disruption to power quality.
Often site inspections reveal scenarios where equipment has been damaged due to poor power supply quality or where fluctuating loads led to damage at power providers’ equipment. The exact causes of such failures can only be determined if there is a clear overview of the quality in the power grid. It is therefore important to consider employing a power quality monitoring device, which could help detect failures early, lead to quick preventative action and assist in improving overall health of the electrical system.
Modern power quality measurement devices can measure various factors in the power quality field, and it is important that the device complies to the relevant South African standard, i.e., SANS 61000-4-30, for accurate reference measurements.
Within this standard the certification known as “Class A” is given to power quality measurement devices that are highly capable due to passing all the given requirements. This class of devices is often also required for legal and trade purposes. Typically, the following should be considered:
- Detailed amplitude values of the sine wave.
- Frequency (which should be 50Hz in South Africa).
- Flicker (a measurement that indicates flicker in light sources).
- Voltage drops or overvoltage.
- Interruptions in supply.
- Asymmetry (where sine waves are shifted).
- Harmonics, and,
- Sudden voltage changes.
In recent developments, some manufacturers have gone beyond these requirements and created devices that can measure switching surges, lightning induced surges (8/20µs) and lightning impulse currents injected into the electrical system (10/350µs). This is typically done by measuring impulses on the earth cable of the electrical system and is useful for detailed root cause analysis, assisting with insurance claims when damage to the system was caused by elements outside the owner’s control.
Detailed overview of power quality within an electrical system is measured by means of PQ measurement devices and can prove to be beneficial for the longevity of equipment, ensuring up-time within a facility during production and assist in keeping the power grid stable. Moreover, being able to monitor and react to power quality deviations remotely with the use of an internet connected smart PQ measurement device is convenient and reduces delays. Considering the challenges in increasingly modern grids, it becomes clear how important smart power quality monitoring is during electrical design and specification for new installations.
Enquiries: www.dehn-africa.com
