Power quality analysis

The PQM-750 analyser is Sonel's answer to the growing demands of the power market. Developed for precise, continuous monitoring of network parameters, it is distinguished by its compact design, modular structure and advanced functionality. Evolution of power quality analysers Sonel has been developing its range of power quality analysers for many years. Starting with the pioneering Sonel PQM-701, through the next generations of Sonel PQM-700 / PQM-707 meters, and ending with the advanc

Non-linear loads such as UPSs, computer PSUs, LED lamps, inverters, air conditioners, etc. draw mains current which is distorted and off-phase with voltage. One of the negative effects of the operation is the generation of capacitive reactive power into the grid. This operation is charged extra by DSOs (applying liquidated/contractual damages), and the costs can be considerable. The issue can be solved in several ways, although one of the simplest and most effective solutions is a dynamic var

Poor power quality can cause a variety of negative effects. From relatively mild ones, like periodic flickering of lights, to very serious ones, like damage to electrical equipment. However, one should always bear in mind that poor power quality is not necessarily the only cause of problems. Other causes can be technical problems, construction problems, design errors, etc. Description of the identified problem A 1250 kVA block transformer at the CHP plant was damaged. After it had been rep

Comprehensive diagnostic measurements of power quality very often require measurements at several points simultaneously. However, connecting several analysers at different points will be of no use if they all do not have exactly the same timing and their measuring terminals are not connected to exactly the same phases. Description of the identified problem Measurements were taken of the operation of a 20 kV/2x690 V MV resin transformer. The transformer windings were in a D/y11/d0 arrangeme

Induction machines, i.e. motors and transformers, should not be operated with little or no load, as their efficiency is then low. Generally speaking, larger squirrel-cage induction motors show an efficiency of more than 80% in the load range of about 40...100%. Power transformers have the highest efficiency in the range of about 30...50% load. Low load operation causes adverse effects such as increased reactive power consumption and a decrease in power factor. Description of the identified pr

Medium-voltage overhead lines often operate close to trees or shrubs. During strong winds, vegetation can cause transients and threats to the continuity of the power supply in the form of sags and blackouts. It is thus important for energy services to take proper care of the transmission infrastructure, e.g. by cutting down trees and shrubs that threaten the lines. Description of the identified problem During the normal operation of the distribution network, there was a period of very stro

Non-linear load points such as UPSs, computer power supplies, LED lighting, inverters, air conditioners, etc. draw distorted current from the mains. One of the negative effects of such operation is the generation of capacitive reactive power into the grid. Electricity suppliers usually do not allow this to happen and charge additional fees that are actually penalties, often significant ones. Description of the identified problem A company producing electronic devices incurred additional ch

Backup power supply is often a critical component of the electricity infrastructure in facilities where safety is fundamental (e.g. hospitals, server rooms) or which incur high loss costs (e.g. manufacturing processes). Internal combustion engine-driven generators are commonly used where power backup is essential. When properly selected and serviced on an ongoing basis, a generator is an effective source of power. Description of the identified problem A generator with a continuous apparent

The times when linear loads, such as induction motors fed directly from the mains, incandescent lighting or thermal equipment, dominated in industry are long gone. Nowadays, most electrical appliances draw more or less non-linear current from the mains. This gives rise to a number of power quality issues, including the most annoying ones, i.e. damage to appliances. Description of the identified problem An industrial facility powered from its own transformer experiences frequent failures of

Unexpected protection failures! Inactivation of devices! Voltage dips! Flickers! What are inrush currents? Each device powered by electricity experiences a moment, when it begins to draw power from the network, which causes the physical effect of increasing current. Examples include starting the drive under load, starting engine at idle, turning on the lights, activating additional level of capacitors, etc. Depending on the purpose and many additional conditions, transient values of this c

The power quality primarily defines voltage changes and fluctuations, voltage unbalance and voltage harmonic distortions. The size and nature of reactive power also have a great influence on the power quality. The low level of the tg (φ) coefficient and keeping it within a narrow range of 0…0.4 has a positive effect on the increase in the efficiency of the use of power cables and transformers and on the improvement of the basic quality parameters. Description of the identified prob

The good power quality also means the lack of interruptions in the supply of electricity. Of the available solutions, diesel generators are the most widely used. They allow you to secure the continuity of power supply both during temporary failures and long-term interruptions occurring in energy distribution systems. Due to temporary working conditions, the EN 50160 standard provides for separate quality parameters in island operation. Description of the identified problem The generator wo

Power quality in industrial facilities is threatened by the commonly occurring starts of high power drives. This causes frequent and deep voltage dips causing the effect of the bothersome flicker. These phenomena in industrial facilities, with a large number of devices with similar properties, become very burdensome and may threaten the health and life of employees. Reduction of the effects of high inrush currents can be achieved by means of power electronic devices, the so-called soft star

Power quality in industrial facilities is threatened by the widespread presence of a large number of power drives. To ensure the resistance of drives to network parameters and easy regulation of technological processes, the best solution is to use inverters. Description of the identified problem The low power inverter is typically equipped with a 6-pulse rectifier. Therefore, it cooperates in a characteristic way with the power grid, and its distorted current has a negative impact on the q

Power Quality (PQ) can be defined according to many criteria. One of them is the EN 50160 standard for public distribution networks. Obtaining reliable and comparable results requires the use of a class A device compliant with the EN 61000-4-30 standard. Description of the identified problem The user connected to the LV 230 V AC distribution network wants to know the power quality at the connection point. Frequent flickering phenomena disturb him greatly. What can be said about the phenome

Overcurrent protections are designed to protect the receiving device and the power line from failure and damage. Their selection results from standard calculations. There may be times when specific receiver properties cause unexpected operation for no obvious reason. Description of the identified problem The DC rectifier supplied from the 230 V AC network is protected by a C10A circuit breaker. Both the operation and the connections are correct (Fig. 1). However, there are occasional circu

It would seem that low-power devices have little impact on the quality of the power supply. Indeed, appearing singly, this is true. However, in large office buildings a natural multiplication phenomenon occurs, which, with synchronous energy consumption at the same moments of the voltage sine wave, is not without consequences. If there is an element of unreliable design solutions related to the minimum price criterion, then trouble is guaranteed. Description of the identified problem The c

The functioning of energy distribution systems ensuring both the reliability and durability in normal and emergency states, requires the use of protective elements. Proper selection of parameters and settings requires detailed knowledge of the character and variability ranges of individual parameters. It may happen that the wrong selection is indicated by unjustified activation of the protection. Description of the identified problem In an industrial facility, one of the machines behaves q

Modern single-phase devices with higher power, made at a higher technical level, are partially protected against drawing distorted current from the network, resulting from the operation of typical rectifier bridges. At the same time, these solutions allow for partial correction of reactive power, keeping it at a low level. These are the most reasonable solutions that integrate a simplified active filter with a rectifier power supply. Description of the identified problem A professional hig

The situation on the energy price market due to geopolitical measures and the 'green transition' is changing very dynamically. The increased costs associated with the production, distribution and sale of electricity are being passed on to end consumers in the form of higher bills for its consumption. Despite the implementation of support measures by governments in many countries to reduce the impact of energy prices, individual consumers, businesses, local governments and educational ins

Optimising electrical power consumption in an era of rapidly rising power prices has become a necessity for both business and private consumers. Many consumers and prosumers have begun to wonder how they can really make a difference in reducing their electricity bills. It is important to first precisely identify the sources of potential losses and only then to tackle them. This usually requires a financial expense. The savings generated must compensate for the expenses incurred on optimisation.

In these days of energy crisis and dwindling resources of fossil fuels, electricity consumers are increasingly looking for ways to reduce their electricity consumption and lower their power bills. The main measures to reduce electricity consumption are optimisation actions, like turning off unused or idle electrical loads, operating electrical loads in their rated conditions (without under or overloading), and using automatic control to ensure rational operation of electrical equipment (e.g. aut

Renewable energy sources such as photovoltaics, wind or geothermal energy constitute an increasing share in energy production in the modern world. A roof covered by photovoltaic panels or a landscape with wind turbines are normal views for us now. It is worth noting that the total installed capacity of photovoltaic installations used in the whole world at the end of 2020, depending on the data source, was between 713 GW[1] and 759 GW[2]. The growing share of electricity production from RES, i

Minimum, maximum, average values! What is it, meaning, interpretation »   IEC 61000-4-30 standard, class A »   Time aggregation »   Synchronization »   Why? What are digital measurements? Although digital measurements have already become a natural method of processing information about physical quantities, it is still difficult to visualize what this measurement is about, and, consequently, what it results from. The basi

Chargers for electric cars. Can they deteriorate the quality of power supply? Introduction At present, it is difficult to imagine societies functioning smoothly without car transport. The number of cars in individual countries is counted in millions, and the vast majority of them are vehicles powered by processed fuels obtained from oil (petrol, diesel). Due to the limited quantity of this natural resource, the rising costs of its extraction and the world’s ecological trends, there i

Beware of asymmetry - causes, consequences, measurement and control Three-phase motors are overheating! Overcurrent breakers are triggering without a reason! Energy bills are higher than expected! Undesirable asymmetry The economic benefits of energy suppliers and their users are strongly dependent on reliability, safety and efficiency of the power system. One of the phenomena that is strongly related to the efficiency of the power system is an asymmetry. Cur

Flickering light and voltage fluctuations. Importance, effects and measurement •    Do you have symptoms of dizziness in areas illuminated by artificial light? •    Your electrical and electronic devices turn off or do not work correctly? Fliker and voltage fluctuations Flicker, otherwise known as the flickering light parameter, is directly related to fluctuations in the supply voltage. This parameter determines the degree of voltage fluctuations

The level of the current exceeds the limit on the conductors! Overcurrent circuit breakers trip and you do not know why! Electric motor overheats and it has excessive vibrations!   What are the harmonic frequencies? The distortion of the power signal in the power network from the shape of the ideal sinusoid indicates a certain harmonic content in this signal. Figure 1 shows three waveforms from a three-phase network with a high degree of harmonic content. The shape of the wavefor

It is almost a year since the SONEL SA release the first Class A PQM-702 power quality analyzer. The company is already known in the world with manufacturing a wide range of measuring instruments for the power industry. After annual presence on the market many customers of the new PQM-702 confirmed high usefulness of measurement and registering data for effective diagnostic of power supply problems. Especially very useful features are built-in GPS modem provides high time accuracy of measurem

From the very beginnings of the power industry, generally up until 1980s, the problem of the quality of the power supply, and phenomena related to it, practically did not exist in Eastern Europe. Along with development in technology and the elimination of economic barriers, equipment processing electric energy started to appear on a large scale in the system. Today, each piece of equipment of the household appliances and audio/video devices, computers, and even lighting, to some extent uses d