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.
Comparision Mechanical Compensation
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.
* Assumed installed power, Cosø: 0.8 inductive and Cosø: 0.9 capacitive
- 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
- 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.
Screen shot from Network Analyzer. All parameters can be tracked via Analyzer's software
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.
Seperate Correction Of Each Phase (EKM) - Capacitive And Inductive Correction with 20ms Correction Speed (EKM - EKT)
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.
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.
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.