New Generation
Electronic Thyristor Controlled
pf Corrector Systems
Improved operating efficiency is crucial and topical subject around the world. Reduction of energy costs is regarded worldwide as one of the crucial challenges to all branches of the industry. Reactive energy is chiefly regarded as one of the causes for the consumption of unusable energy and that is why reducing reactive energy usage has traditionally been one of the simplest ways to conserve energy.Today, Conventional Compensation Systems are the most common solution providers to eliminate the reactive energy. However, Conventional Compensation Systems kick in within 5 to 10 seconds when there is a need for reactive energy correction. Such a long time interval causes overloading and significant losses on the network. Considering the sum of all losses caused by hundreds and thousands of end users, the amount of total loss reaches to intolerable levels to electrical distribution companies. This is why it has become a common practice for them to confine the end users in their reactive energy consumption and even reflecting the fines on their electrical bills for their excess usage of reactive energy. Conventional Compensation Systems take the current in one phase to correct other two phases. At unbalanced loads it causes capacitive penalty when the current is high and also insufficient compensation when the current is low.
Since current compensation systems make correction by activating / deactivating capacitor blocks with contactors, they cause voltage transients, arcs, spikes and electrical noises during switching. The clear-cut difference between contactor-controlled and thyristor controlled systems is shown in the oscilloscope screen shots 1 and 2. When this situation is extrapolated for all industrial users, the corollary is that the mains get congested and it can give drastic damage to critical loads. This uncontrolled switching at capacitor blocks can even cause short circuit, contactor switches getting
fused, and even fires. This is why hundreds of contactor switches and capacitor blocks are replaced each year.

Screen Shot 1: Capacitor Activation with Contactor

Screen Shot 2: Capacitor Activation with Thyristor

With Karmet Electronic Compensation Systems (EKM), switching is made through 5 thyristor - diode modules positioned at 5 arms with binary logic, which means 32-step capacitive correction. At each arm, also harmonic filters, connected serial to capacitors are used, which not only limits the current going to capacitors but also suppress the system harmonics perfectly. The performance of this new generation systems during its operation with the line is recorded to Fluke 435 Analyzer (Table 1 and Table 2). Unbalances or distortions are eliminated by the separate correction of each phase.

As can be observed in Tables 1 and 2, while the active total power is steady (61 kW – 65 kW), total active and reactive power drops significantly to prevent the overloading at mains and transformers.
Comparision Mechanical Compensation
  • Each phase controlled independently enabling the device to handle unbalanced loads at optimum level.
  • Increased capacitor life with zero current switching.
  • 32 step capacitive and 2 step inductive sensitivity correctio
  • Semiconductor switching increases reliability.
  • Periodic test of capacitors and semiconductors gives prior failure detection.
  • Modular construction and easy service.
  • Remote communication supervision and monitoring.
  • Easy construction with standard current transformer.
  • Energy saving with unbalanced loads.
  • Solves current harmonics with harmonic filters.
  • No current peaks, no dangerous transients and line pollution.
  • Series inductors for damping PFC capacitors.
* Assumed installed power, Cosø: 0.8 inductive and Cosø: 0.9 capacitive

Screen shot from Network Analyzer. All parameters can be tracked via Analyzer's software

Block Schema

Electronic pf Corrector Module (EKKM)
Cutting Edge Technology
Thyristor controlled threephase electronic compensation with 32 step sensitivity
New generation Electronic Compensation Module (EKM) and Electronic Compensation Threephase (EKT) are designed in such a way that they completely eradicates the energy losses caused by classical compensation systems.

32 Step at 5 Arms with Binary Logic
The 5 arms are switched via thyristor-diode modules with binary logic, thus the resulting step value is calculated to be 2^5 = 32. For example, when the capacitor value at first arm starts with 200 uF (4 kvar), the value at the final arm would be 3200 uf (64 kvar) and the resulting total capacity of the module becomes 124 kvar (4+8+16+32+64) with 4 kvar sensitivity. To match 75 kvar need, 1., 2. and 5. arms are switched and the 76 kvar monophase capacitor is activated.

Harmonic Suppression
At each arm, installed harmonic filters (being serial to capacitors) not only limit the current going to capacitors but also suppress the system harmonics and the resulting harmonics of fast switching perfectly.

Seperate Correction Of Each Phase (EKM) - Capacitive And Inductive Correction with 20ms Correction Speed (EKM - EKT)
Load unbalances among phases are perfectly eliminated with separate correction of each phase. The number of activated capacitors is limited to the actual requirement
at each phase. Capacitive reactive load correction is also maintained at each phase with a similar logic. Added reactor to sixth arm can also be set in motion via thyristor
module if inductive kvar is needed.

Longer Component Life with Zero Current Switching
Zero current switching of thyristor diode modules enables the current at capacitors to increase gradually, starting from zero to maximum level, which in turn prolongs the overall lifetime of capacitors significantly. In addition, the current is also limited thanks to harmonic filters that are connected serial to capacitors.

Modular Architecture, Easy Installation
Thanks to its modular configuration, modules can be connected in parallel to EKM and EKT series when there is a need for capacity increase, bringing lower investment cost for the long term. Its configuration is with wiring to current modules and bars only. In case of a failure with one of the modules, the other two continue to operate with no disruption.

Parallel Operation with Classical Systems
When the system comprises fast changing loads with stable ones, EKM module working in parallel with the classical system would be the best solution to compensate the changing load.

Network Analyzer
All energy parameters (i.e. cosø, PF, KVAR, KVA, kW, current harmonics...) can be observed and tracked via Digital Network Analyzer. In addition all parameters can be monitored and reported via Network Analyzer through RS485.
Technical Specifications And Models

3 Phase Module Control unit.
Parallel Operation With Classical Systems

When the system comprises fast changing loads with stable ones, EKM module working in parallel with the classical system would be the best solution to compensate the changing load.
Operation with Generators