Mfumo wa kuthibitisha wa viwango vya kiwango chache, kama vile ambavyo hazitoshi katika utambulishaji na usalama wa mifumo ya umeme, mara nyingi huwa na magonjwa mengi wakati wanatumika pamoja na mifumo mingine ya umeme kutokana na sababu za mazingira, matatizo ya uhusiano wa mifumo, na ubuni na huduma isiyofaa. Magonjwa haya si tu huathiri kazi sahihi ya mifumo ya umeme, lakini yanaweza pia kuweka maumivu. Kwa hivyo, ni muhimu kufafanulia kwa undani aina za magonjwa, njia za kuhakikisha, na hatua za kupunguza ili kuhakikisha kazi sahihi na imara ya mitundu ya umeme wa mashinani na mifumo ya kiwango chache.
I. Vipengele Vinavyohusiana Na Mfumo Wa Umeme Wa Kiwango Chache
Mfumo wa kuthibitisha wa viwango vya kiwango chache unatumika kwa kubadilisha na mipengele yafuatayo katika mifumo ya umeme, kujenga vibao tofauti:
Mifumo ya kuthibitisha ya viwango: Huunganishwa na silaha za kuthibitisha kama vile watt-hour meters na power meters ili kuthibitisha kwa ujasiri viwango vya umeme vya wateja. Katika mitundu ya umeme wa mashinani, vinavyopatikana kwenye sanduku la wateja au upande wa chini wa transformers, wanaweza kutumika kubadilisha viwango vya umeme vikubwa hadi kiwango cha viwango vidogo vya 5A au 1A.
Silaha za kuzingatia: Huunganishwa na silaha za kuzingatia kama vile circuit breakers, residual current protectors, na overload protectors ili kukazia macho kwa hali ya viwango vya umeme na kugongwa kwa viwango visivyo sahihi. Katika sanduku la umeme wa mashinani, yanaweza kutumika kubainisha uzito wa mzunguko, kushuka kwa barabara, au leakage.
Mifumo ya utaratibu wa kiotomatiki: Huunganishwa na silaha za kiotomatiki kama vile PLCs na RTUs kwa ajili ya ukaguzi na utambulishaji wa mbali wa hali ya mifumo ya umeme. Yanapatikana katika eneo la mashinani, steshoni za maji, na sehemu zingine.
Transformers: Huunganishwa na mzunguko wa mwisho wa transformers kwa ajili ya kubainisha hali na uzito wa transformers. Yanapatikana kwenye mzunguko wa mwisho wa transformers wa mashinani.
II. Magonjwa Yasiyofaa Wakiwemo Katika Mfumo Wa Umeme Wa Kiwango Chache
1. Gonga La Mzunguko Mwisho
Gonga la mzunguko mwisho ni moja ya magonjwa yasiyofaa sana ya mfumo wa kuthibitisha wa viwango vya kiwango chache, inayotajwa:
Dalili: Onyo la ammeters na power meters kinabadilika kuwa zero au kunyanyapanya; transformer anapoonyesha sauti asili "buzzing" au discharge sound; kuna dalili za kuchoka kwenye terminal block; watt-hour meter anastahimili au kunyanyapanya.
Sababu: Terminal block zenye ubuni; wire za mzunguko wa mwisho zinavyovunjika wakati wa kuweka silaha; kuvunjika kwa hisani wakati wa huduma; uhusiano usio mzuri kutokana na oxidation; wire za mzunguko wa mwisho zinavyovunjika kwa nguvu.
Matatizo: Kilovolts kadhaa yanaweza kutengenezwa kwenye mzunguko wa mwisho, kuchukua usalama wa wafanyakazi; iron core inaonekana kwa wingi na kuchoka, kuchoka kwa insulation materials; silaha za kuzingatia huenda kutekeleza kazi isiyofaa.
Ushindi wa kawaida: Katika eneo la transformer, wire za mzunguko wa mwisho zilivyovunjika kwenye terminal block zilikaza kuchoka, kuleta kuchoka kwa meter na kuchukua usalama.
2. Gonga La Uhusiano Usio Bora
Uhusiano usio bora ni moja ya magonjwa yasiyofaa sana:
Dalili: Onyo la ammeters linabadilika, kuna joto la transformer; silaha za kuzingatia hutetea kwa kasi; kuna ongezeko la viwango; kuna oxidation na blackening kwenye terminal block.
Sababu: Screws zenye ubuni; contact area isiyo suficiente; oxidation au corrosion; aging za materials; torque isiyofaa; resistance inaongezeka kwa hali ya mvua.
Matatizo: Joto linaloongezeka, kuchoka kwa insulation; viwango vilivyotarajiwa kusababisha ongezeko la viwango; silaha za kuzingatia hutetea kwa kasi; kuchoka kwa muda mrefu.
Ushindi wa kawaida: Katika mzunguko wa kuthibitisha unaotumia copper wires, resistance inaongezeka kwenye temperature rise.
3. Gonga La Overload Na Iron Core Saturation
Overload na iron core saturation ni magonjwa yasiyofaa sana, inayotajwa:
Dalili: Onyo la ammeters linabadilika; transformer anachoka; silaha za kuzingatia hutetea kwa kasi; viwango vilivyotarajiwa kusababisha ongezeko la viwango; sauti asili kutokana na iron core.
Sababu: Magonjwa yanavyotarajiwa kwenye mifumo ya umeme (kama vile peak electricity consumption); accuracy limit factor isiyofaa; short-circuit current inayozidi capacity; degradation ya material ya iron core; magnetic permeability inaongezeka kwa joto.
Matatizo: Iron core saturation inasababisha ongezeko la viwango, kuchoka kwa insulation; silaha za kuzingatia hutetea kwa kasi; transformer anachoka.
Ushindi wa kawaida: Transformer alipata iron core saturation, kusababisha ongezeko la viwango na silaha za kuzingatia hutetea kwa kasi.
4. Gonga La Degradation Ya Insulation Performance
Insulation faults ni magonjwa yasiyofaa sana, inayotajwa:
Dalili: Resistance inachoka (should be ≥1000MΩ under normal conditions); partial discharge phenomenon; surface discharge marks; increased leakage current; dampness or water stains on the equipment surface.
Sababu: Hali ya mvua na sealing isiyofaa; damage kutokana na gnawing of small animals; accelerated insulation aging due to long-term high-temperature operation; reduced insulation performance due to dust accumulation on the terminal block; insulation breakdown caused by lightning overvoltage.
Matatizo: Degraded insulation performance leads to leakage or short circuits; misoperation of protection devices; increased metering errors; and may even cause fires in severe cases.
Ushindi wa kawaida: Katika eneo la mashinani, resistance inachoka kwa sababu ya humidity inayozidi 80%.
III. Njia Za Kuhakikisha Magonjwa Yasiyofaa
1. Hakikisha Gonga La Mzunguko Mwisho
Meter observation method: Check whether the indication of connected ammeters and power meters suddenly becomes zero or fluctuates significantly; whether the watt-hour meter stops rotating or rotates abnormally.
Sound identification method: Approach the transformer body and listen for abnormal "buzzing" or discharge sounds; the sound should be small and uniform during normal operation.
Temperature detection method: Use an infrared thermometer to detect the temperature of the transformer body, which should be ≤40℃ under normal conditions; it may reach above 60℃ when open-circuited.
Impedance testing method: Use a special instrument to measure the impedance of the secondary circuit. The impedance angle is independent of frequency when connected normally; the impedance increases significantly (>10000Ω) when open-circuited.
Rural scenario judgment skill: In rural low-voltage metering boxes, if it is found that the electric meter suddenly stops working while farmers' electricity usage is normal, the secondary circuit of the current transformer should first be suspected of being open-circuited.
2. Hakikisha Gonga La Uhusiano Usio Bora
Loop resistance testing method: Use a micro-ohmmeter to measure the secondary circuit resistance, which should be ≤0.65mΩ under normal conditions; the resistance may exceed 1mΩ when there is poor contact.
Temperature rise monitoring method: Use an infrared thermometer to monitor the temperature rise of the terminal block, which should be ≤15℃ under normal conditions; the temperature rise may exceed 30℃ when there is poor contact.
Vibration detection method: Use a vibration sensor to detect abnormal vibrations. When there is poor contact, the vibration amplitude may exceed 2g and last for more than 10 seconds.
Load testing method: Connect a standard load to the secondary circuit of the transformer and observe whether the output current is stable; the current may fluctuate when there is poor contact.
Rural scenario judgment skill: In metering boxes after rural network centralized reading transformation, if it is found that the metering of a certain household's electric meter is abnormal while that of other households is normal, focus should be on checking the connection status of the secondary circuit of the current transformer for that household.
3. Hakikisha Gonga La Overload Na Iron Core Saturation
Current monitoring method: Check whether the actual load current on the primary side exceeds the rated value; special attention should be paid to peak electricity consumption periods in rural power grids, such as the Spring Festival and the irrigation season.
Error testing method: Use a transformer calibrator to test the ratio error and phase error, which should meet the accuracy level requirements under normal conditions; errors may increase significantly during overload or saturation.
Excitation characteristic testing: Measure the secondary voltage under different currents and draw the excitation curve; the slope of the curve will change significantly when the iron core is saturated.
Sound identification method: The iron core may make abnormal noise when saturated; the sound should be small and uniform during normal operation.
Rural scenario judgment skill: On the low-voltage side of rural distribution transformers, if it is found that protection devices frequently malfunction when multiple high-power electrical appliances are operating simultaneously, the current transformer should be suspected of being overloaded or having iron core saturation.
4. Hakikisha Gonga La Degradation Ya Insulation Performance
Insulation resistance testing method: Use a 2500V megohmmeter to measure the insulation resistance between the primary and secondary, secondary to ground, and primary to ground; it should be ≥1000MΩ under normal conditions.
Partial discharge testing method: Use a partial discharge tester to detect internal discharge in the transformer; the discharge amount will increase when insulation performance degrades.
Visual inspection method: Check whether there are water stains, dirt, or damage on the transformer surface; whether there is dust accumulation or signs of animal gnawing on the terminal block.
Humidity detection method: Use a hygrometer to detect the humidity of the transformer installation environment; a humid environment in rural areas may lead to degradation of insulation performance.
Rural scenario judgment skill: In southern rural areas, if it is found that the insulation resistance of the transformer has decreased significantly, focus should be on checking whether the sealing structure is intact and whether the environmental humidity is too high.
IV. Solutions to Common Faults
1. Handling of Open Circuit Fault in Secondary Circuit
Emergency treatment: After discovering an open circuit fault, immediately deactivate the relevant protection devices; use insulating tools to short-circuit the secondary side at the terminals near the transformer; if there is a spark during short-circuiting, it indicates that the fault point is in the circuit below the short-circuit point; if there is no spark during short-circuiting, the fault point may be in the circuit before the short-circuit point.
Long-term solutions: Replace the secondary wiring terminals with reliable quality; use gold-plated or tinned terminal materials to reduce oxidation; install anti-loosening gaskets or Snap-on limiters to prevent vibration-induced loosening; regularly check the connection status of the secondary circuit.
Rural scenario handling suggestions: In rural low-voltage metering boxes, secondary circuit short-circuit protection devices can be installed to automatically short-circuit when an open circuit is detected; regular inspections should be conducted by electricians, especially before peak electricity consumption periods.
2. Handling of Poor Contact Fault
Maintenance measures: Use a torque wrench to tighten terminal screws according to specifications (such as 0.8-1.2N·m for M4 screws); regularly clean the oxide layer on terminals; apply conductive paste to terminal contact surfaces; inspect and replace aging or damaged terminal blocks.
Preventive measures: Install moisture-proof heaters at terminal block connections (automatically start when humidity >60% RH); use G4-grade filter cotton to block dust (replace every 6 months); adopt metering boxes with IP65 protection level; regularly inspect and maintain terminal blocks.
Rural scenario handling suggestions: In rural network metering boxes, gold-plated or tinned terminal materials can be used; shockproof terminal blocks can be adopted; terminal connection status should be checked once a quarter; the inspection frequency should be increased during the humid season.
3. Handling of Overload and Iron Core Saturation Faults
Protection configuration: Select transformers with appropriate transformation ratios according to the actual line load; protection current transformers should select appropriate accuracy limit factors (such as 10P15 can withstand 15 times the rated current); configure residual current circuit breakers matching the cross-sectional area of the wires at the incoming line (such as 2.5mm² copper wires with C20A protectors) .
Selection suggestions: Select transformers with a rated secondary current of 1A or 5A according to line length and load conditions; 1A transformers are suitable for long-distance metering; in rural power grids, iron core materials with good anti-saturation performance (such as permalloy) can be selected.
Rural scenario handling suggestions: At the incoming lines of farmers' homes, select appropriate protection devices according to the wire diameter (such as 1.5mm² copper wires with C10A, 2.5mm² with C20A, 4mm² with C25A); on the low-voltage side of distribution transformers, reserve sufficient transformer capacity according to load conditions; adopt intelligent monitoring devices to monitor the operating status of transformers in real-time.
4. Handling of Insulation Performance Degradation Fault
Maintenance measures: Regularly check whether the sealing structure of the transformer is intact; use silicone rubber sealing rings to enhance sealing; install moisture-proof heaters in metering boxes; clean dirt on the transformer surface.
Preventive measures: Select metering boxes with IP65 protection level; use flame-retardant ABS materials for the shell; use moisture-proof wiring terminals at the terminal block; conduct regular insulation resistance tests.
Rural scenario handling suggestions: In southern rural areas, epoxy resin-cast transformers can be adopted; install temperature and humidity monitoring devices in metering boxes; regularly inspect and replace aging sealing materials; install lightning arresters in lightning-prone areas.
