Vipi ni changamoto za kawaida za current transformers katika air-insulated switchgear?
Salamu, mimi ni Felix, na nimekuwa nafanya kazi katika shughuli za mfumo wa umeme kwa miaka minne. Kutoka kutumaini wazee wa uhusiano katika eneo la kazi hadi kuongoza timu zinazohusiana na matatizo mengi ya vifaa vya substation, nimefanya kazi na aina mbalimbali za current transformers (CTs), hasa hizo zinazotumika katika air insulated switchgear (AIS).
Ingawa vifaa hivi vinahitajika kidogo tu katika ustawi na rahisi kudhibiti, yanaleta matatizo mengi wakati wa kutumika kwake. Leo, nitashiriki tajriba yangu na kuzungumzia:
Ni matatizo yanayofanikiwa ya current transformers katika air insulated switchgear — na jinsi tunavyowezekana kusikia?
Hakuna maelezo yoyote, tu maarifa ya kutumika!
1. Ni Nini Current Transformer Katika Air Insulated Switchgear?
Ngumuja na maelezo fupi ili kukusaidia kuelewa vizuri zaidi.
Air Insulated Switchgear (AIS) ni aina ya vifaa vya utambulishaji wa umeme unachotumia hewa kama chanzo kuu cha kingomeko. Inatumika sana katika mitandao ya utambulishaji hadi 35kV.
Current transformer (CT) ndani yake anapostawishwa karibu na circuit breakers au isolating switches. Kazi yake ni kuhesabu current primary na kupata ishara za sampling kwa vifaa vya protection. Ufanisi wa CT unadai kasi kwa umehesabi na uhakika wa vitendo vya protection.
2. Aina Za Matatizo Yanayofanikiwa na Tathmini Ya Sababu
Matatizo 1: Secondary Open Circuit — Matatizo Yenye Hatari (na Mara Mengi Inachokoni)
Dalili: Meters hausho maonyesho, protection relays huenda hayafanyi kazi au hujaa.
Sababu:
Mizigo ya terminal yenye ubavu;
Kukosa kutengeneza secondary circuit wakati wa kutest;
Hitilafu za binadamu wakati wa kutumia.
Matokeo: Secondary circuit yenye upasuaji unaweza kusababisha core saturation na kutengeneza voltage yenye hatari — inaweza kuongeza vifaa au kusababisha hatari za usalama.
Solutions:
Angalia mizigo yote ya secondary kabla ya kutengeneza;
Endelea kutumia shorting links wakati wa kutest;
Jifunza wanafunzi wa dhibiti juu ya procedures sahihi.
Tipi: Baada ya kila majaribio, angalia secondary loop na multimeter ili kuhakikisha kuwa unaendelea!
Matatizo 2: Insulation Aging / Moisture Ingress — Hatari Kubwa Wakati wa Upgrading Substation Zilizopita
Dalili: Partial discharges, insulation resistance imepungua, breakdown trips.
Sababu:
Uzito wa muda wa materials;
Sealing yenye ubavu inayamkuria moisture kuondoka;
Mazingira yenye humidity kali (yasema kwa wingi katika maeneo ya kusini).
Matokeo: Matatizo madogo yanaweza kusababisha tahadhari ya measurement; matatizo makubwa yanaweza kusababisha short circuits au explosions.
Solutions:
Fanya tests ya insulation mara kwa mara;
Prioritize designs zenye ukuzu kwa wakati wa kutengeneza units zilizopita;
Instala heating na dehumidifying devices katika mazingira yenyewe.
Tafadhali: Wakati wa upgrading stations zilizopita, usitegeme tu kwenye mapicha — angalia insulation ndani!
Matatizo 3: Wrong Polarity Connection — Hitilafu Kamili na Matokeo Makubwa
Dalili: Differential protection huenda hayafanyi kazi, metering yenye ubavu.
Sababu:
Kukosa kutathmini polarity wakati wa kutengeneza;
Kukosa kuelewa wiring diagrams;
Labeling yenye ubavu inayosababisha wiring yenye ubavu.
Matokeo: Katika systems za differential protection, polarity yenye ubavu inaweza kusababisha false tripping au failure to trip — hatari kubwa.
Solutions:
Tathmini polarity baada ya kutengeneza;
Tumia polarity tester au DC method kutathmini direction;
Elezea primary na secondary terminals.
Hatari: Polarity ina umuhimu — hasa wakati wa kutumia relay protection systems!
Matatizo 4: Ratio Error Too Large — The “Silent Killer” Ambaye Anasababisha Metering na Protection
Dalili: Discrepancies katika energy meter readings, incorrect protection settings.
Sababu:
Improper CT selection (rated current mismatch);
Poor magnetization curve of the core;
Excessive secondary load (e.g., connecting multiple instruments).
Matokeo: Errors madogo hutumia pesa katika billing; errors makubwa husababisha misjudgment by protection relays.
Solutions:
Carefully match the rated current during selection;
Check if the secondary load is within acceptable limits;
Replace with higher accuracy class CTs when necessary.
Attention: Don’t downgrade accuracy classes lightly — especially for metering applications!
Matatizo 5: Mechanical Damage or Poor Assembly — Hidden Risks from Installation
Dalili: Abnormal vibration, loud noise, overheating.
Sababu:
Physical damage during transportation;
Forced alignment during installation;
Improper tightening of mounting bolts.
Matokeo: Long-term operation may lead to winding deformation or insulation damage.
Solutions:
Inspect for physical damage before installation;
Follow installation instructions strictly;
Use torque wrenches to tighten fasteners properly.
Field Experience: It’s better to take your time than rush and leave hidden dangers behind!
3. Daily Operation & Maintenance Tips
As an experienced field engineer, here are some key O&M suggestions I want to emphasize:
Regular Patrols: Monitor temperature, sound, and connection status;
Insulation Testing: Perform insulation resistance and dielectric loss tests at least once a year;
Live Detection: Use infrared thermal imaging to detect abnormal heating early;
Data Logging: Keep historical records to track trends;
Training: Improve operational standards through staff training, especially for new employees.
4. Final Thoughts
Current transformers in air insulated switchgear may seem small and unimportant, but they're the eyes and ears of the entire power system. When they fail, it can range from minor metering inaccuracies to serious safety risks.
So whether you're selecting, installing, or maintaining these devices — pay attention to the details!
Remember these key points:
Prevent secondary open circuits at all costs;
Never allow polarity errors;
Monitor insulation aging regularly;
Control ratio errors strictly;
Ensure high-quality installation.
Only by getting every detail right can we truly guarantee stable and safe power system operations.
If you’ve encountered any CT-related issues in your work, or want to know more about troubleshooting a specific fault, feel free to leave a comment or send me a message. I’d be happy to help you analyze and solve the problem together!
Here’s hoping every current transformer runs steadily and safely — quietly guarding our power supply!
— Felix
