Mataas nga harmoniko? Ang imong transformer mao nga mobati ug molabay ngadto sa pagkatulo.

Ang ulohan sa report na niini gibuhat batas sa pag-analisa sa usa ka adlaw nga datos sa kalidad sa kuryente sa imong kompanya nga sistema sa distribusyon. Ang datos nagpakita nga may significant nga distorsyon sa harmoniko sa tulo-phas nga kuryente sa sistema (nga may mataas nga total nga distorsyon sa harmoniko sa kuryente, THDi). Sumala sa internasyonal nga standar (IEC/IEEE), ang mga harmoniko sa kuryente sa kini nga nivel naghimo og substantial nga mga panganak sa safe, reliable, ug ekonomical nga operasyon sa tranformador sa kuryente, main manifested sa additional nga heat generation, pagbawas sa serbisyo nga buhata, ug padayon pa sa pagdamage sa tranformador.

1. Overview of Test Data

• Monitored Parameter: Total Harmonic Distortion of Three-Phase Current (A THD[50] Avg [%] L1, L2, L3)

• Monitoring Duration: 4:00 p.m. on September 8, 2025 to 8:00 a.m. on September 9, 2025 (Rwanda Time)

Data Source: FLUKE 1732 Power Logger

• Durante sa panahon sa monitoring, ang total nga harmonic distortion sa tulo-phas nga kuryente (THDi) gibag-o sa mataas nga nivel (e.g., consistently around 60%).

• Kini nga harmonic level significantly exceeds the recommended good practice range (THDi < 5%) and the general allowable range (THDi < 8%) for distribution systems specified in international standards such as IEEE 519-2014 and IEC 61000-2-2.

2. Mechanism of Harmonic Current Impact on Transformers (Problem Analysis)

Ang mga tranformador gi-disenyo sumala sa pure 50Hz sinusoidal current. Ang mga harmoniko nga kuryente (espesyalmente ang 3rd, 5th, ug 7th harmonics) moguhit og duha ka core issues:

• Doubled Eddy Current Loss: Ang eddy current loss sa winding sa tranformador proportional sa square sa frequency sa kuryente. Ang high-frequency nga harmonic currents moguhit og sharp increase sa eddy current loss, far exceeding the design value based on fundamental current.

• Additional Heat Generation and Thermal Stress: Ang gisulti nga extra losses gi-convert ha heat, resulta sa abnormal nga temperature rises sa winding ug iron cores sa tranformador.

3. Risk Assessment Based on International Standards

Sumala sa provisions sa IEC 60076-1 ug IEEE Std C57.110 regarding transformer operation under non-sinusoidal current, ang main risks posed by the current harmonic level to your transformer include:

• Risk 1: Accelerated Insulation Aging and Severe Service Life ReductionThe service life of a transformer is directly determined by its operating temperature. The rule of thumb indicates that for every continuous 6-10°C increase in winding temperature, the insulation aging rate doubles, and the expected service life of the transformer is halved accordingly. Long-term overheating will cause the transformer insulation to become brittle, eventually leading to breakdown faults.

• Risk 2: Reduced Actual Load-Carrying Capacity (Derating Required)To avoid overheating, the transformer cannot operate at its rated capacity under the current harmonic level. According to the calculation method in IEEE Std C57.110, the transformer must be derated (for example, when THDi is 12%, the derating factor may need to be 0.92 or lower). This means that a transformer with a rated capacity of 1000kVA may have an actual safe load-carrying capacity of less than 920kVA, limiting the system's capacity expansion potential.

• Risk 3: Increased Transformer Field StrengthAccording to the electromotive force formula Et = 4.44 ⋅f⋅Φm (where f is frequency), harmonics generate high-frequency magnetic flux, which induces significant eddy currents in the winding conductors, leading to local hot spots and overheating. The over-frequency of harmonics acts as an "amplifier" — even if the amplitude of the harmonic magnetic flux Φmh is small, its high-frequency characteristic will amplify the induced turn-to-turn electromotive force by h times. This amplified electromotive force is applied to the winding insulation, especially the first few turns of the coil, causing local overvoltage and greatly increasing the risk of insulation breakdown.