Misalai da ayyukan da za a iya amfani da su don inganta hanyar kawo gaba na tashin jirgin saman kungiyar?

Tap changing under load is a method of voltage regulation that allows a transformer to adjust its output voltage by switching tap positions while operating under load. Power electronic switching components offer advantages such as frequent on/off capability, spark-free operation, and long service life, making them suitable for use as on-load tap changers in distribution transformers. This article first introduces the operational regulations for on-load tap-changing transformers, then explains their voltage regulation methods, and finally outlines key precautions for on-load tap-changing operations. Please read on with the editor for detailed information.

1. Operational Regulations for On-Load Tap-Changing Transformers

• When operating an on-load tap-changing transformer, a second tap change must not be initiated until the first tap change is fully completed. Voltage, current, and other parameter changes should be closely monitored during the process.

• Each tap-changing operation must be recorded in the main transformer tap-changing logbook, including the operation time, tap position, and cumulative number of operations. Records must also be maintained for all commissioning/decommissioning events, tests, maintenance activities, defects, and fault handling.

• Maintenance of the on-load tap changer shall follow the manufacturer’s specifications. In the absence of such specifications, the following guidelines may be applied:

• Oil samples from the tap changer compartment should be tested after 6–12 months of operation or after 2,000–4,000 switching operations.

• For newly installed tap changers, the switch mechanism should be lifted out for inspection after 1–2 years of service or after 5,000 operations. Subsequent inspection intervals may be determined based on actual operating conditions.

• The insulating oil in the tap changer compartment should be replaced after 5,000–10,000 operations or when the oil’s breakdown voltage drops below 25 kV.

• For on-load tap changers that have remained unused or unmoved for an extended period, a full cycle of operation between the highest and lowest tap positions should be performed whenever a power outage opportunity arises.

2. Situations Where On-Load Tap-Changing Is Prohibited:

• When the transformer is operating under overload conditions (except in special circumstances).

• When the light-gas relay of the on-load tap-changing device has tripped and issued an alarm.

• When the insulating oil dielectric strength of the tap-changing device is unqualified or the oil level indicator shows no oil.

• When the number of tap changes has exceeded the specified limit.

• When abnormalities occur in the tap-changing device.

• When the load exceeds 80% of the rated capacity, operation of the on-load tap changer is prohibited.

3. Voltage Regulation Methods for On-Load Tap-Changing Transformers

3.1 "Boots-On" Retrofit Method

The "boots-on" approach involves opening the neutral point of the high-voltage three-phase windings of the main transformer and inserting series-connected regulating windings from a compensation transformer. The low-voltage side of the main transformer is connected in parallel with the excitation winding of the compensation transformer to achieve on-load voltage regulation. This method relies on the principle of voltage superposition: the compensator, through an on-load tap changer, maintains the high-voltage winding voltage of the main transformer within its rated range.

In this configuration, the compensator only withstands the neutral-point voltage or the N-level tap voltage (e.g., 2×OU1), requiring a relatively low insulation level. When the transformer neutral point operates under solidly grounded conditions, an insulation level of 35 kV is sufficient (we design and manufacture for 40 kV), though higher levels can be adopted based on specific operational requirements. This method requires only one additional neutral-point regulating transformer, resulting in low retrofit costs. Field modifications involving the neutral-point lead can be completed within one working day. If integrated with a major transformer overhaul, it adds virtually no extra downtime.

This method is suitable when voltage fluctuations exceed the range achievable by no-load (off-circuit) tap changers—i.e., even when the off-circuit tap changer is at its highest or lowest position, the voltage still fails to meet standards. Our neutral-point on-load tap-changing transformers provide a wide ±12% U₁ₙ regulation range. When used in conjunction with the original off-circuit tap changer, the effective regulation window can be shifted up or down more flexibly to meet actual needs and enhance the main transformer’s output capacity. The required regulation range can be customized based on site conditions, making this solution adaptable to transformers of all voltage levels. We have successfully retrofitted four main transformers using this approach. However, this method does require additional space for one extra transformer and slightly more complex primary wiring. Nevertheless, considering the short retrofit duration and cost savings, it remains an economically sound and reasonable solution.

3.2 "Backpack" Retrofit Method

The "backpack" method is a more economical and practical retrofit approach when the existing off-circuit tap changer’s range already meets local voltage fluctuation requirements. It involves disconnecting the tap leads from the original off-circuit tap changer, removing the switch, and installing a bridging-type or linear on-load tap changer in its place, with the original tap leads rerouted to the new on-load switch.

Aikin da ya zama da aka yi a kan wasu lokaci na aiki mai yawa. Aikin gaba (kamar kawo takura na tanka ko kasa shi) zai taka rana ne kuma zai iya haɗa da aiki na ayyuka na aiki; tankin ko cibiyar zai gudanar da haka a wani lokaci. Abin da ke nufin shine in samun aiki na dukkan a wani rana bila tabbacin aiki, saboda idan an yi lafiya zai saukar da lalacewa da kuma zai zama da abincin.

Kuma, domin transformafi na biyu ba ta da masu sauran hanyoyin bayyana aiki na wannan aikin, ya kamata a yi ayyukan gaba don in ba da fage da kyau a cikin duk mota da transformafi da kuma in ba da karfin aiki na gaba (kamar ƙananan juna cibiya/tanki). An yi ayyukan gaba a wurin wannan hanyoyi, an samun sadarwa mai ma'ana, kuma an rage shirye-shiryen aiki mai amfani da shi. Daga baya, an yi aiki na wannan hanyoyi a cikin shida transformafi, an samun duk abubuwan da aka tabbatar, kuma an ba da shahara a cewa shi ne aikin mai ma'ana da kuma mai kyau.

4. Tushen da Duk Daidai a Aiki na Bayyana Tap Don In Yadda

• Bayyanar tap zai iya a yi tsakanin, tare da tafiya mai girma a kan bayanin tap, tasiri, da kula. Ba a yi lafiya zuwa wata aiki na bayyana, kafin a yi lafiya zuwa wata aiki na biyu.

• Don sakamakon transformafi na banki na fase kadan ko transformafi na tatuwa da bayyana tap na fase, ya kamata a yi aiki na tatuwa da elektronika; babu a yi aiki na fase kadan a wani lokaci.

• Idan an yi aiki na tatuwa transformafi na bayyana tap:

• Ba a yi bayyana tap ba a lokacin da kula na aiki ya kai ko kadan 85% na kula na transformafi.

• Babu a yi labaran bayyana tap a kan wata transformafi; kammala bayyana a kan wata transformafi kafin a yi aikin na biyu.

• Ba a yi bayyana tap ba, tarka a duba tasiri da kula don in ba da misauna da kula mai yawa.

• A lokacin da aiki na kafa tasiri, ya kamata a yi bayyana a kan transformafi na kula mai kadan kafin a yi aiki a kan wata na kula mai yawa, don in kawo sanya kula mai yawan mulki. Kafin aiki na kusa tasiri, ya kamata a yi aiki a kan wata na kula mai yawa kafin a yi aiki a kan wata na kula mai kadan.

• Daga baya, duba ƙananan kula da kuma kula mai yawa a kan tatuwa transformafi.

• Idan an yi aiki na tatuwa transformafi na bayyana tap da transformafi na bayyana tap na biyu, ya kamata a yi bayyana a kan wata transformafi na bayyana tap kafin a yi aiki a kan wata na bayyana tap na biyu.

• Yawan bayyana tap da ake amfani da shi a wata rana:

• 30 bayyana a kan rana don transformafi na 35 kV,

• 20 bayyana a kan rana don transformafi na 110 kV,

• 10 bayyana a kan rana don transformafi na 220 kV.

• Kafin a yi bayyana tap, duba cewa faruwar tasiri na sistem da tasiri na bayyana tap ta dogara da tashizun bayanin.

• Har da aiki na bayyana tap, ya kamata a rubuta shi a cikin kitabta bayanin aiki na bayyana tap don in ba da shahara.