Generated reactive power of the bank/system is the power generated at the operational voltage, expressed in Mvar.

Power factor or cosΦ, is a measurement of the efficiency in the system. Power factor describes the relationship between active and apparent power.

The frequency at which the filter impedance, calculated from the rated values, has a minimum or maximum value. (IEC 61642)

Filter is a device generally constituted by reactors, capacitors and re-sistors if required, tuned to present a known impedance over a given frequency range. (IEC 61642). Usually active harmonic filter and passive harmonic filter are used in networks.

Shifting reactive power: caused by inductive and/or capacitive loads. These ensure current ‘lags/runs late’ behind the voltage (inductive) or that the current ‘leads/runs ahead’ of the voltage (capacitive). Distortive reactive power: this is the ‘unwanted’ part of the apparent power associated with harmonic pollution caused by non-linear loads.

To a greater or lesser extent, reactive power is present In each electrical installation. This presence is closely related to the ever-increasing use of electronics and inductive loads.

With an ohmic/resistive load, available power in the installation is directly converted into usable energy. Examples include electric ovens, light bulbs and radiators. The current in this case is in phase with the voltage.

1.Overloading and overheating of the electrical installation and connected components (cables, transformers….) 2.Capacity problems on the installation 3.Unintentional shutdown of installed machines and related business processes 4.An unnecessarily high energy bill due to energy losses 5.A fine from the energy supplier 6.Influence the voltage and quality of the current

The best choice here depends on extent of any interruption. Uninterruptible power supplies and other energy-storage options could do well with shorter-term sags or interruptions, but back-up generators or self-generation equipment is needed when longer outages are encountered. Other solutions could include static transfer switches and dynamic voltage restorers with energy storage

Measurement and analysis are the critical first steps in any power-quality improvement program. Putting what you’ve learned to use, though, means knowing the best solutions for the problems you’ve identified. 

Harmonics can lead to serious problems • Reduced energy efficiency when harmonics are in the network • Overheating of cables, motors and transformers • Damage to sensitive equipment • Tripping of circuit breakers • Blowing of fuses • Premature ageing of the installation • Capacitor overloading and failures • High current in neutral conductors • Excitation of network resonance • No connection permit from the utility if harmonic levels are too high

ZDDQ PQS Active Harmonic Filter solutions for efficient and reliable operation in hospitals or data centres. Harmonics condition and requirement in Hospitals and data centres Hospitals Hospitals are places where reliable power distribution is needed to guarantee patient health,save lives. Continuity and reliability of power supply are extremely important. Automatic power restoration time of different healthcare venues is as follows: category 0 venues t≤15s; category 1 venues 0.5s≤t≤15s; and category 2 venues t≤0.5s. The use of new moden electrical devices, such as CT scanners, MRI scanners, X-ray machines, and others is increasing in hospitals. Device loads contain massive harmonic current, and can impact the hospital power networks,thereby reducing power quality. Harmonic mitigation and management is necessary to ensure the safety of hospital distribution systems. Data Centres Data Centres are places where reliable power supply is necessary to guarantee the stability of datas.Continuity and reliability of power supply with lower harmonics are extremely important. UPSs are increasingly common as data centres pursue a reliable power supply. As most UPSs use 6-pulse or 12-pulse rectifiers, a high volume of harmonic current can flow into the grid and affect grid stability. Power quality problem description in hospitals Harmonics affect lighting stability and interfere with precision medical instruments such as CT scanners, MRI scanners and ECGs, reducing examination accuracy and ultimately affecting physician diagnoses of patients’ conditions. In addition, massive harmonic current also reduce the stability of hospital distribution systems, which result in power outages due to tripping and the necessity of harmonic elimination. Solution Referring to onsite inspection, pilot testing and assessment, an Acitve Harmonic Filter is installed at the secondary site of the LV distribution transformer. Conclusions After implementing an Active Harmonic Filter in a large hospital, the lighting system became stable, there were reduced reports of extreme noise interference on instruments, machine stability was enhanced, failure and maintenance frequency was reduced, and harmonic impact on the stability and safety of the hospital distribution system were eradicated. ZDDQ Recommened PQ products for Hospitals and data centres Active Power Filter Active Harmonic Filter Static Var Generator Advanced static var generator