Vipimo vinginevyo vinavyohitajika kufanywa kwenye mizizi ya umeme?
Ukosefu wa Taarifa kutoka kwa Muhendis wa Umeme katika Nyanja
Na Oliver, Miaka 8 katika Sekta ya Umeme
Habari zenu wote, mimi ni Oliver, na nimekuwa naajiriwa katika sekta ya umeme kwa miaka 8.
Tangu mapenzi yangu ya awali katika uanuzi wa steshoni na utambuzi wa vifaa, hadi sasa kunawasaidia kusimamia uzalishaji na utambuzi wa matatizo ya mipango yote ya umeme, moja ya vifaa vilivyokuwa vinavyokutana sana katika kazi yangu ni voltage transformer (VT / PT).
Hivi karibuni, rafiki yangu ambaye ameanza tu alinini:
“Utambuzi unaojitokeza gani unaufanyika kwenye voltage transformers? Na jinsi unavyojua kama kuna tatizo?”
Swali nzuri! Wengi wa wafanyakazi wa nchi hawajui kwa ujumla isipokuwa kama mizigo yameunganishwa au kama kuna volts — lakini kuelewa kwa kutosha hali ya afya ya PT, inahitaji utambuzi wa kibinafsi.
Leo, nitakubainisha kwa lugha rahisi — kutegemea kwa tajriba yangu ya miaka minne iliyopita — utambuzi gani unaojitokeza kwa mara nyingi kwenye voltage transformers, sababu za muhimu, na jinsi ya kutekeleza.
Hakuna lugha ngumu, hakuna masharti yanayofikia — tu maarifa yanayoweza kutumiwa katika maisha halisi.
1. Kwa Nini Kutambua?
Ingawa voltage transformer inaonekana rahisi, ina uzoefu wa kudumu katika nyuso tatu muhimu: utambuzi, utaratibu, na usalama.
Ikiwa kitu kimoja kitenda vibaya, inaweza kupeleka:
Utaratibu wasio sahihi;
Usalama usio sahihi au kutofunguka;
Kupoteza utambuzi wa volts katika nchi yote.
Kwa hiyo, kutambua mara kwa mara ni muhimu — ni kama kutambua PT yako kamili. Inaweza kukusaidia kupata matatizo mapema na kuzuia matukio makubwa.
2. Aina Tano Zenye Kutambua Zaidi kwenye Voltage Transformers
Kutegemea kwa miaka minne yangu ya tajriba, hizi ni mitambuzi minne yanayoumeti kutumika na muhimu:
Utambuzi 1: Utambuzi wa Uwezo wa Insulation
Lengo: Kuchunguza insulation kati ya windings na kati ya windings na ardhi.
Hii ni moja ya mitambuzi msingi na muhimu zaidi.
Insulation chache kinaweza kuleta interferences, short circuits, au hata explosions.
Jinsi ya kutambua:
Tumia megohmmeter wa 2500V kwa primary to secondary and ground;
Tumia megohmmeter wa 1000V kwa secondary to ground;
Pima uwezo wa insulation kati ya primary na secondary, primary to ground, na secondary to ground;
Mulinganisha na data za zamani — madhara makubwa yanahitaji kutambuliwa zaidi.
Maswala yangu:
Lazima kufanyika kwenye majukumu mpya;
Sehemu ya uhifadhi wa mwaka;
Pia tumia baada ya kuwa katika majanga, lightning strikes, au events za tripping.
Utambuzi 2: Utambuzi wa Ratio
Lengo: Thibitisha kwamba ratio ya voltage halisi inaonekana sawa na value ya nameplate ili kuhakikisha ukurasa sahihi na usalama.
Kwa mfano, PT yenye rating ya 10kV/100V lazima aoutput within tolerance; kinginevyo, protection relays zingeweza kutenda vibaya.
Jinsi ya kutambua:
Tumia voltage chache (kwa mfano, 100V–400V) kwenye upande wa primary;
Pima voltage ya secondary na hesabu ratio halisi;
Mulinganisha na nameplate — error acceptable ni ±2%.
Tajribati:
Ratio mismatch inaweza kuonyesha inter-turn shorting;
Maraheliano, ni wiring isiyosahihi, kama polarity reversed;
Safiri tena baada ya mabadiliko ya terminal au repairs.
Utambuzi 3: Utambuzi wa Excitation Characteristic (Volt-Ampere Curve)
Lengo: Thibitisha ikiwa core imefunika au ina dalili za aging au moisture ingress.
Utambuzi huu ni muhimu hasa kwa electromagnetic VTs, hasa ambazo zipo katika systems zinazokubalika ferroresonance.
Jinsi ya kutambua:
Tumia AC voltage kwenye secondary winding;
Ongeza voltage kwa polepole na rekodi current values;
Plot the U-I curve na angalia knee point.
Maelezo muhimu:
Curve normal itaonyesha knee point clear;
Curve smooth, non-kinked inaweza kuonyesha core saturation;
Initial slope steep inaweza kuonyesha moisture damage.
Case halisi: Mara nyingi nimepata excitation characteristics abnormal kwenye PT — ilikuwa imeingia maji kutokana na sealing chache. Baada ya kuyaza, ilirudi kwa normal.
Utambuzi 4: Utambuzi wa DC Resistance
Lengo: Kuchunguza broken strands, turn-to-turn shorts, au poor connections kwenye windings.
DC resistance testing inaweza kukuza defects chache ndani ya windings.
Jinsi ya kutambua:
Tumia DC resistance tester;
Pima resistance ya both primary na secondary windings;
Mulinganisha results na factory values au measurements previous — deviation should not exceed ±2%.
Maelezo muhimu:
Temperature affects results — best to compare under similar conditions;
On large PTs, allow time for discharge before testing to avoid residual charge errors.
Utambuzi 5: Dielectric Loss Factor (tanδ) Test
Lengo: Assess the aging or moisture condition of insulation materials.
This advanced test is often used for high-voltage VTs, especially capacitive voltage transformers (CVTs).
Jinsi ya kutambua:
Tumia tanδ tester;
Apply a set voltage and measure the dielectric loss factor;
Typically acceptable value is tanδ ≤ 2% (varies by device).
Matatizo yanayofanikiwa:
High values suggest insulation degradation or moisture;
If standard isn't met, consider drying or replacement.
3. Additional Auxiliary Testing Methods
In addition to the five main tests, these supplementary methods are also useful:
Infrared Thermal Imaging
Detect overheating at connection points;
Identify hotspots early;
Especially useful for monitoring operating equipment.
Partial Discharge Detection
Detect weak internal discharges;
An effective early warning for insulation degradation;
Recommended for high-voltage PTs in critical applications.
Wiring Inspection + Polarity Test
Ensure correct wiring and consistent polarity;
Prevent metering inaccuracies or protection misoperations.
4. My Final Suggestions
As someone with 8 years of field experience, I want to remind all professionals:
“Don’t wait until the voltage transformer fails before thinking about testing.”
Performing regular comprehensive checks every year not only ensures stable system operation but also greatly extends the life of your equipment.
Here are my recommendations for different roles:
For Maintenance Personnel:
Learn to use basic instruments (megohmmeters, multimeters, ratio testers);
Understand each test procedure and standard;
Record test data regularly and build comparison records.
For Technical Staff:
Master advanced tests like excitation curves and tanδ;
Combine infrared and partial discharge detection to improve diagnostics;
Understand the PT’s role in the system to avoid blind operations.
For Managers or Procurement Teams:
Clarify testing requirements during equipment selection;
Request complete factory test reports from suppliers;
Establish lifecycle management and schedule regular inspections.
5. Closing Thoughts
Voltage transformers may seem small, but they play a crucial role in the entire power system.
They’re not just about stepping down voltage — they’re the eyes of the system, the ears of protection, and the heart of metering.
After 8 years in the electrical field, I often say:
“Details determine success or failure, and testing ensures safety.”
If you ever encounter abnormal PT behavior, unusual test results, or don’t know how to diagnose a problem, feel free to reach out — I’m happy to share more hands-on experience and solutions.
May every voltage transformer run stably and safely, safeguarding the accuracy and reliability of our power grid!
— Oliver
