Vipi ni sababu za kutokufanya kwa transforma ya vito vya ferromagnetic katika steshoni za umeme wa nishati mpya

Na Felix, Miaka 15 katika Sekta ya Umeme

Habari zenu wote, mimi ni Felix, na nimekuwa na kazi katika sekta ya umeme kwa miaka 15.

Tangu uwezeshaji wa awali wa steshoni za umeme na huduma zinazofuata hadi sasa kunawakilisha mikakati ya umeme ya jua limara na upindeleaji wa umeme kutoka pumzi za upepo, chombo cha kiotomatiki ambacho ninaweza kupata mara nyingi ni Tanshia ya Uvuti wa Umeme (PT).

Siku moja, mfanyikazi wa kifuniko kwenye eneo la nyuklia mapya aliniuliza:

“Tuna tanshia ya uvuti wa umeme inayotoka kwa joto sana, kukwaa kwa njia isiyotarajiwa, na mara nyingi hii huwasilisha kwa matatizo ya usalama. Kuna kitu kinachotokea?”

Hii ni tatizo linajihusisha sana, hasa katika viwanda vya nyuklia mapya. Kama chombo muhimu cha ukimbiaji na usalama, ikiwa PT inashindwa, inaweza kuleta hatari kubwa kutoka kwenye ukimbiaji usio sahihi hadi kujitoa kwa nguvu kabisa au kushindwa kwa vifaa.

Leo, ningependa kuzungumzia:

Ni matatizo yoyote yanayowezekana ya tanshia za uvuti wa umeme? Kwanini yanavyokua? Na jinsi tunavyoweza kutathmini?

Hatutumaini lugha ya kiufundi — tu maumivu yangu ya kila siku niliyozijikuta kwa miaka mingi. Hebu tuangalie kwa undani zaidi ni kile kinachotokea kwa "rafiki yetu mzee" huyu.

1. Ni Nini Tanshia ya Uvuti wa Umeme?

Hebu tuanze kwa kuangalia kwa undani zaidi kuhusu kazi yake asili.

Tanshia ya uvuti wa umeme, inayojulikana kama VT au PT, ni transformer wa kuchelewa ambayo hutumika kutekeleza voltage ya juu kwa voltage chache (kawaida 100V au 110V), ambayo hutumiwa na mashine ya ukimbiaji na mikakati ya usalama.

Mfumo wake ni rahisi: primary winding una magamba mengi na mwisho mdogo, unahusiana na upande wa voltage juu; secondary winding una magamba machache na mwisho mkubwa, unahusiana na mikakati ya kudhibiti.

Ingawa, kwa sababu ya mfumo huu, inaweza kuhusishwa na mazingira ya kufanya kazi, mabadiliko ya ongezeko, na majukumu ya kidhati.

2. Matatizo Yanayowezekana na Uchanganuzi wa Sababu

Kulingana na tajriba yangu ya miaka 15 katika shughuli, matatizo yanayowezekana zaidi ni:

Matatizo 1: Joto La Juu Au Hata Mwanga/Kuiva

Hii ni moja ya matatizo yanayobainisha hatari — inaweza kuleta upungufu wa insulation au hata moto.

Sababu Zingine:

• Secondary short circuit au overload (mfano, mikakati mingi za usalama zinazohusiana kwa parallel bila kutathmini uwezo);

• Core saturation (hasa wakati wa ferroresonance);

• Insulation aging au moisture ingress;

• Terminal loose causing high contact resistance na heat localized.

Mfano Halisi:

Marra moja, nimepata PT anayotoka kwa joto sana katika steshoni ya PV step-up — infrared thermography ilionyesha joto zaidi ya 120°C. Waktumie kutafuta, tuliona kuwa secondary winding insulation imekula kwa umbali. Sababu ilikuwa ni open circuit condition kutokana na disconnected secondary breaker wakati bado connected kwa high-impedance meter.

Maelekezo:

• Usione PT secondary kuendelea kuwa open-circuited — ingawa siyo ngumu kama CTs, inaweza kuleta voltage distortion na ukimbiaji wasio sahihi;

• Tumia infrared thermography mara kwa mara kutathmini temperature za terminal na enclosure;

• Ikiwa utapata joto la juu, tumia mara kwa mara kutathmini.

Matatizo 2: Ferroresonance Inayosababisha Voltage Fluctuations

Hii ni moja ya matatizo yanayopewa uhamisho lakini yanayotokana na hatari katika viwanda vya nyuklia mapya.

Dalili:

• Voltage three-phase unbalanced;

• Voltage fluctuating up and down na sound ya buzzing;

• Protection misoperations au false trips;

• Mara nyingi ground signals false zinatokea.

Sababu Asili:

• Katika mikakati isiyokolewa au arc suppression coil grounded systems, wakati capacitance line-to-ground hutumika na PT excitation inductance under certain conditions, ferroresonance inaweza kutokea;

• Inaweza kutokana na breaker switching, sudden loss of voltage, au single-phase grounding.

Mfano Halisi:

Katika wind farm, kila wakati main transformer alikuwa energized, PT alitokana na sound ya humming, na bus voltage ilikuwa ina fluctuate wildly, hata kuisababisha standby auto-switch incorrect. Baada ya utafiti, ilikuwa ni ferroresonance. Kuweka damping resistor katika open delta ilisolve the problem.

Maelekezo ya Prevention:

• Install anti-resonance devices (kama vile open-delta resistors au microprocessor-based suppressors);

• Tumia anti-resonant type PTs (kama JDZXW series);

• Improve operation mode ili kuevita non-full-phase operation;

• Wakati wa outage maintenance, perform magnetizing curve tests kutathmini core saturation tendency.

Matatizo 3: Secondary Voltage Output Chache au Haipo

Matatizo haya mara nyingi huathiri ukimbiaji na logic ya usalama, na mara nyingi huathirika kama vifaa vingine vinavyoshindwa.

Sababu Zingine:

• Primary fuse blown (kawaida baada ya lightning strikes au overvoltage events);

• Secondary fuse blown au air switch tripped;

• Polarity au ratio setting incorrect;

• Inter-turn short circuits katika internal windings;

• Oxidized au loose terminal connections.

Mfano Halisi:
Katika PV station moja, SCADA ilionyesha bus voltage chache. Kutafuta kwenye eneo, tuliona kuwa PT primary fuse imeburudika. Replacing it restored normal operation. Further analysis showed it was caused by a voltage surge from nearby lightning.

Steps za Troubleshooting:

• Check fuses and breakers first;

• Measure primary and secondary voltages for consistency;

• Verify wiring and polarity;

• Perform ratio test and insulation resistance test if necessary.

Matatizo 4: Internal Discharge au Insulation Breakdown

Hii mara nyingi hutokea katika mazingira ya maji au ya chafu, hasa katika maeneo ya pwani au mataa.

Dalili:

• Smell of burning au discharge marks visible kwenye housing;

• Crackling sounds during operation;

• Reduced insulation resistance;

• In severe cases, explosion au tripping occurs.

Sababu Zingine:

• Moisture ingress causing insulation deterioration;

• Surface dirt au dust buildup reducing creepage distance;

• Long-term overloading au harmonic effects;

• Manufacturing defects au transport damage.

Mfano Halisi:

PT installed near the coast repeatedly tripped during the rainy season. Inspection revealed clear signs of internal discharge — the root cause was poor sealing allowing moisture to enter.

Countermeasures:

• Increase protection rating (IP54 or higher);

• Install dehumidifiers au space heaters;

• Regular cleaning and drying;

• Conduct insulation and partial discharge tests before commissioning.

Matatizo 5: Human Error au Wiring Mistakes

Human error remains a major cause of many incidents.

Common Mistakes Include:

• Switching isolators under secondary load;

• Reversed polarity causing incorrect metering au protection misjudgment;

• Accidental removal of grounding wires leading to floating potentials;

• Performing live work without proper safety measures.

Mfano Halisi:

A new technician replaced a PT secondary fuse without disconnecting the power, causing a short circuit — the fuse holder burned out and nearly caused injury.

Key Takeaways:

• Strengthen training and standardize procedures;

• Clearly label wiring to prevent mistakes;

• Enforce lockout/tagout procedures to eliminate live work;

• Ensure one-point grounding of all PT secondary circuits.

3. My Suggestions and Field Experience Summary

As a 15-year veteran in the electrical field, I always say:

“Though small, the electromagnetic voltage transformer plays a critical role in measurement, metering, and protection.”

It may not be as noticeable as a circuit breaker or as large as a transformer, but once it fails, it can trigger a chain reaction.

So here are my recommendations:

For Daily Operation & Maintenance:

Regular inspections — listen for unusual sounds, smell for burning, and measure temperature;

• Check fuses, breakers, and grounding integrity;

• Record operational data and compare with historical trends;

• Increase inspection frequency before and after thunderstorm seasons.

For Fault Diagnosis:

• Prioritize checks on secondary circuits and fuses;

• Use multimeters to verify voltage levels;

• Conduct insulation resistance, ratio, and magnetizing characteristic tests when needed;

• Take immediate action to suppress resonance if suspected.

For Equipment Selection:

• Consider environmental factors (humidity, altitude, salt fog);

• Prefer anti-resonant PTs;

• Choose appropriate rated capacity to avoid long-term overloading;

• Leave room for redundancy to support future expansion.

4. Final Thoughts

Although structurally simple, electromagnetic voltage transformers play a vital role in new energy power plants.

They act like the "eyes" of the power system, telling us exactly how "high" the voltage is.

After 15 years in the field, I firmly believe:

“Details determine success or failure. Safety comes above everything.”

If you're dealing with tricky PT issues on site, feel free to reach out — I'm happy to share more hands-on experiences and troubleshooting methods.

May every PT operate stably, keeping our grid safe and intelligent!

— Felix