​LV TRANSFORMER AND REACTOR SOLUTIONS

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Renewable Power Electronics Applications

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In renewable energy systems, inverter outputs create much more challenging operating conditions compared to conventional systems due to high harmonic content (THDi 30–60%), high dv/dt, high di/dt, and rapid load changes.

OMSAN approaches these problems not with a standard product approach, but with application-specific engineering solutions.

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PROBLEM: HIGH HARMONICS AND LOSSES

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Harmonics originating from the inverter:

• Increases THDi to 30–60%
• Creates eddy current and stray loss in the windings
• Causes local overheating and efficiency reduction

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OMSAN SOLUTION

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OMSAN optimizes LV/LV transformers and line reactors together to solve this problem.

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HOW IT DESIGNS

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• Analyzes the harmonic spectrum in detail (not just THDi, but also distribution)
• Sizes the transformer according to effective RMS loading
• Designs to be compatible with K-Factor (K-13 / K-20)
• Determines the leakage reactance (Z%) according to inverter compatibility
• Optimizes the conductor geometry against skin & proximity effect
• Calculates losses depending on harmonic frequencies

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HOW IT PRODUCES

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• Winds the coils homogeneously and with low losses
• Provides complete insulation and thermal resistance with VPI
• Applies low contact resistance connections
• Controls the partial discharge level <10 pC

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RESULTS

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• THD: 30–60% → can be reduced to <5%
• Additional losses are significantly reduced
• Temperature rise is controlled

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PROBLEM: HIGH dv/dt AND INSULATION STRESS

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Fast voltage fluctuations at the inverter output:

• Create stress on the insulation system
• Cause partial discharge and premature failures

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OMSAN SOLUTION

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OMSAN implements a high dv/dt withstand LV/LV transformer design.

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HOW IT DESIGNS

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• Selects the insulation system according to the dv/dt level
• Optimizes the winding structure to balance the voltage distribution
• Controls the electric field density

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HOW IT PRODUCES

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• Provides gapless insulation with VPI
• Applies uniform insulation placement between windings
•Verifies quality with partial discharge tests

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RESULT

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• Insulation stress is reduced
• Risk of failure is lowered
•Equipment life is significantly extended

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PROBLEM: HIGH di/dt AND CURRENT PEAKS

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Rapid current changes:
• Damage inverter semiconductors
• Create sudden current peaks
• Create electromagnetic stress in the system

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OMSAN SOLUTION

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OMSAN controls current dynamics with LV line reactors.

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HOW IT IS DESIGNED

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• Determines the required inductance based on system analysis
• Optimizes within a 3–5% reactance range
• Adjusts the impedance characteristic according to harmonic frequencies

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HOW IT IS MANUFACTURED

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• Applies air gaps with precise tolerances
• Creates a balanced magnetic field by ensuring winding symmetry
• Provides resistance to electromagnetic forces with a mechanically robust structure

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RESULT

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• di/dt is limited
• Current peaks are reduced
•Inverter protection level is increased

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PROBLEM: THERMAL STRESS AND OVERHEATING

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Harmonics and high RMS current:

• Causes excessive temperature increase in transformers and reactors
• Reduces insulation life

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OMSAN SOLUTION

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OMSAN designs thermally optimized transformers and reactors.

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HOW IT DESIGNS

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•Performs hot-spot analysis
• Optimizes current density
• Selects core and conductor to minimize losses

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HOW IT PRODUCES

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• Designs balanced cooling channels
• Creates a mechanical structure that improves heat dissipation
• Increases thermal conductivity with resin application

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RESULT

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•Temperature rise is reduced
•Thermal stress is reduced
• Equipment life is extended

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PROBLEM: SYSTEM INSTABILITY AND RESONANCE

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Incorrect impedance and filter design:

• Can create resonance
• Can destabilize the system

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OMSAN SOLUTION

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OMSAN designs transformers and reactors together to control system impedance.

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HOW IT DESIGNS

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• Optimizes leakage reactance (Z%)
• Performs LCL filter and resonance analyses
• Balances system impedance

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HOW IT PRODUCES

• Precisely controls inductance tolerances
• Provides stable magnetic structure

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RESULT

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•Resonance risk is eliminated
• The system operates stably

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GENERAL SYSTEM IMPROVEMENT

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With OMSAN solutions:

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• THD → decreases from 30-60% to <5%
• Current waveform → approaches a sine wave
• Thermal load → significantly reduced
• Risk of failure → minimized
• Equipment life → significantly increased

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CONCLUSION

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With OMSAN solutions:

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• Analyzes the problem
• Designs the product accordingly
• Guarantees quality through controlled production

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and makes the system:

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• More efficient
• More stable
• Longer lasting