Ukomoaji wa Mv & Hv Kabeli kwenye Vifaa & Joints

Matatizo ya Kawaida na Mawaziri kwenye Kuzima wa Umeme

Wakati wa kuzima mzunguko wa umeme katika vifaa vya uhamiaji ndani, moto wa umeme, muhuri za nguvu, muhuri za mstari, na vifaa vingine vya kiwango cha kati (MV, ambako kiwango cha volti ni (1 kV<V<60 kV) ) na kiwango cha juu (HV, na V≥60 kV), matatizo mengi yanavyoonekana. Matatizo haya mara nyingi yanatokana na utaratibu mzito wa mikakati ya kuzima, hasa zinazohusiana na vifaa vya uhamiaji. Kutatua matatizo haya kwa ufanisi, unawezeshaji mkosehe na wafanyibiashara wa vifaa ni si tu inapatikana bali pia ni muhimu.

Mawaziri Katika Kuzima wa Mifano ya Umeme na Mabadiliko ya Kablai ya Chini ya Ardhi na Kubadilisha kabla ya Ufukuo

Mawaziri Katika Kuzima wa Mifano ya Umeme

Katika kuzima mifano ya umeme, seti kamili ya mawaziri lazima liangaliziwe kwa ujasiri ili kutayari usalama, uwepo, na ufanisi:

• Basi na Msingi wa Usimamizi: Muktadha, chombo, na nguvu ya basi na msingi wao wa usimamizi ni muhimu. Yanapaswa kukabiliana na maghari ya umeme, nyoka za kiungo, na nguvu za kiungo ya kitamaduni huku wanahifadhi usambazaji na ustawi.

• Muktadha wa Insulation ya Circuit Breaker: Utuhemo wa insulation ndani ya circuit breakers ni muhimu kwa kuwasilisha maghari ya umeme. Inapaswa kukabiliana na kiwango cha volti kilichochaguliwa, overvoltages ya muda, na mazingira bila kushindwa.

• Tathmini ya PD (Partial Discharge): Kutathmini partial discharge inaweza kupata ishara za mwanzo za degradation ya insulation. Partial discharges zinaweza kuonyesha madhara yanayoweza kuwepo katika mfumo wa insulation, ambayo ikiachishwa, inaweza kuleta failures kubwa.

• Chombo cha Insulation: Chaguo la chombo cha insulation, sio oil, sulfur hexafluoride (SF6), au vacuum, lina athari kubwa kwenye performance. Kila chombo lina faida zake na maeneo yake ya mapovu kwa ukuu wa insulation, uwezo wa kuchoma arc, impact ya mazingira, na mahitaji ya huduma.

• Hali ya Mfumo wa Wedging: Mfumo wa wedging, ambaye anahakikisha vifaa vinavyokuwa katika nyanja, lazima awe na hali nzuri. Mfumo wa wedging unaopotelewa unaweza kuleta majengo mabaya, resistance ya umeme imeongezeka, na joto lisilo la busara.

• Aina ya Gas ya Cooling: Kwa mifano yenye mifumo ya cooling ya gas, aina ya gas inayotumiwa huathiri heat dissipation na performance kamili. Viwanja vya tofauti vya gas viwa na thermal conductivity na ukoo wa heat - carrying tofauti.

• Umbali wa Vifaa vilivyokutwa kwenye High - Voltage Conductors: Nyanja ya vifaa vilivyokutwa kwenye high - voltage conductors ni muhimu. Umbali mfupi unaweza kuongeza hatari ya leakage ya umeme, flashovers, au interferences, kuhitaji insulation na umbali sahihi.

Kuzima kwa Kubadilisha Kablai za Chini ya Ardhi kwenye Mbadiliko ya Overhead Lines

Kuzima kwa kubadilisha kablai za chini ya ardhi kwenye mbadiliko ya overhead lines, ambayo mara nyingi inatafsiriwa kama OH/OG terminations, inajihusisha kwa mtazamo mkubwa katika mitandao ya distribution ya umeme. Kuzima haya zinatumika kwa mifumo iliyochaguliwa volti hadi 36 kV. Maongo yao muhimu yamefanya ni kuunganisha mfumo wa distribution kwenye switchgears zilizojengwa ndani au nje, na kuwasilisha umeme kwa kutokufuatilia sababu za overhead lines kuyelekea mikahawa.

OH/OG terminations zinaweza kutumika na kablai za oil-paper na cross-linked polyethylene (XLPE) insulated, ambazo zinaweza kuwa single-core au three-core. Zinajengwa nje na zinajaribishwa kwenye msingi wa metal ambao amejipanga vizuri kwenye poles za overhead line zilizojengwa kutoka kwa mti, concrete, au metal, kama linavyoelezwa kwenye Fig. 1.

Maagizo muhimu ya usalama kwa OH/OG terminations ni kwamba msingi wao wa metal lazima awe na grounding sahihi. Hii ya grounding inaweza kuzuia shocks za umeme, kusondesha fault currents, na kuhakikisha usalama wa umeme wa mfumo mzima.

Maagizo kwa Msingi wa Metal na Upatikanaji wa Kablai, na Kuzima Elbow

Maagizo kwa Msingi wa Metal na Upatikanaji wa Kablai wa OH/OG

Urefu wa msingi wa metal wa OH/OG (Overhead/Underground) si wa kawaida; lazima ifufuliwe kwa utaratibu wa minimum safety distance ya insulation kwenye ardhi kama ilivyotakikana kwa standards za kiwango cha biashara. Ufuatiliaji huu ni muhimu kwa kutayari usalama wa watu, vifaa, na mfumo wa umeme mzima, kusaidia kuzuia hatari za umeme kama accidental contact au arcing kwenye ardhi.

Wakati wa upatikanaji wa kablai kwa terminations za OH/OG, zinapaswa kuwekwa upande wa pole ulio chanya kwa trafiki inayokuja. Upatikanaji huu unapunguza hatari za uzalishaji kutoka kwa magari, huku akina usalama na muda wa kazi wa infrastructure ya umeme. Pia, kwa muda wa upatikanaji na baada ya kablai kuwekwa katika nyanja zao za mwisho, ni muhimu kwamba hazijapinda zaidi ya minimum internal bending radius iliyochaguliwa na wafanyibiashara. Kuanguka hii ya maagizo hii inaweza kuleta saratani ndani ya cable insulation na conductors, inaweza kuleta failures za umeme. Katika baadhi ya maslahi, kuhakikisha kwamba minimum bending radius imetolewa, poles za refu zinaweza kuwa zarurifu, kuongeza tathmini moja katika mashirika ya upatikanaji na upatikanaji.

Elbow Terminations

Cable terminations zinatumika kwa mara nyingi kusambaza kablai kwenye terminals za vifaa mbalimbali, ikiwa ni transformers, motors, na switchgears zilizojengwa kabla. Lakini, kutokana na masharti tofauti za upatikanaji wa umeme au tabia ya terminals za vifaa, kuna wakati ambapo kusambaza kabla kwenye bushings inahitaji kuwa sealed. Katika maslahi kama hayo, elbow terminations, kama ilivyoelezwa kwenye Fig. 2, ni chaguo la chaguo. Terminations hizi za specialization hivi tu wanaweza kupatia connection ya umeme safe lakini pia kuwasilisha ufaaaji wa sealing, kunywesha mfumo wa umeme kutoka kwa environmental elements na kutayari ufanisi wake.

Elbow Terminations na Utumishi wao katika Ring Main Units (RMUs)

Elbow terminations hutoa ajira muhimu na special, hasa wakati wa kusambaza kablai kwenye bushings za Ring Main Units (RMUs). RMUs ni mifano machache, self-contained, na fully insulated switchgear systems ambazo mara nyingi hutumia sulfur hexafluoride (SF6) kama medium ya insulation. Zinatumika kwa wingi katika mitandao ya secondary distribution, ambazo zinatoa role muhimu katika manajimento na distribution ya umeme kwenye kiwango cha kimataifa.

Moja ya features muhimu za RMUs ni muktadha wao wa internal arc withstand, ambao unongeza usalama na uwepo wa mfumo wa umeme. Sehemu zilizopo za RMUs zimeundwa ili ziwe maintenance-free, kurekebisha hitaji wa interventions za mara kwa mara na kupunguza downtime. Pia, tabia modular yao inawezesha uongezaji rahisi katika eneo la upatikanaji, kudhibiti mfumo kusambaza power demands zinazobadilika kwa muda.

Fundi za switching na protection katika RMUs zinaweza kufanyika kwa kutumia switch-disconnectors pamoja na fuses au circuit breakers. Muktadha hii hutayari mfumo wa umeme kuwa isolated safely, faults zinaweza kupata quickly detected na cleared, na integrity ya mitandao ya distribution inaweza kutayari.

Elbow terminations si tu zinaweza kutumika kusambaza kablai kwenye bushings za RMU lakini pia zinaweza kutumika wakati kabla zaidi zinahitaji kuunganishwa kwenye bushing moja ya vifaa vya umeme. Kama ilivyoelezwa kwenye Fig. 3, terminations hizi zinatoa suluhisho la practical na reliable kwa connections complex za kabla-to-equipment, kusaidia distribution efficient ya umeme huku wanahakikisha integrity na usalama wa mfumo mzima.

Elastimold Cable Joints & Terminations

Elastimold ni brand maarufu ambayo inatoa range kamili ya vifaa na accessories kwa splicing na termination ya kabla, iliyoundwa kwa kiwango cha volti hadi 36 kV.

Terminations za kabla za Elastimold zinapatikana kwa designs ya single-piece na modular. Models hizi versatile zinaweza kutumika kwa applications mbalimbali, ikiwa ni transition kutoka underground cables kwenye bare overhead conductors, connections kwenye live-front equipment, na elbow connections, kudhibiti kwamba zinaweza kutumika both indoors na outdoors. Zinaweza integrated seamlessly into oil, SF6, na air-insulated high-voltage switchgear, pamoja na transformers, motors, na capacitors.

Designs za Elastimold products zimetumia advanced silicone rubber insulating materials. Materials hizi hutoa resistance essential against creep, electrical strikes, weathering, na contamination, huku wanahakikisha performance ya reliable hata katika mazingira harsh. Nature compact na lightweight ya Elastimold units allows for easy installation katika confined spaces na enables free-hanging applications.

Vifaa vya Elastimold pia ni ATEX-certified. ATEX, derived from the French title of the 94/9/EC (European Commission) directive "Appareils destinés à être utilisés en ATmosphères Explosibles" (Equipment to be installed in explosive atmospheres), high-voltage bushings hizi zinaweza kutumika katika oil or air-insulated switchgear na transformers katika hazardous areas, kama vile zinazopatikana katika industries za oil, gas, na petrochemical. Manufacturing ya vifaa vya Elastimold inafuata international standards set by IEC (International Electrotechnical Commission), ANSI/IEEE (American National Standards Institute/Institute of Electrical and Electronics Engineers), na CENELEC (European Committee for Electrotechnical Standardization).

Elastimold inatoa several specialized devices kwa specific applications:

• Separable Elbow Connectors and Accessories: Hizi ni load-break connectors ambazo zinatoa njia convenient ya kusambaza na kutofautiana kabla na vifaa katika power distribution systems. Load-break elbows zimeundwa kwa energized operation using standard hot-stick tools, enabling load make/break operations na providing a visible disconnect. Components zinaweza kutofautiana kutumia insulated caps, plugs, na parking bushings.

• Metal Oxide Varistor (MOV) Surge Arresters: Arresters hizi ni fully shielded na fully-submersible, designed for overvoltage protection. Zina interfaces za 200 A separable connector kwa easy attachment kwenye accessories zingine za Elastimold. Arresters za Elastimold zinatoa high-voltage protection against lightning na switching surges for transformers, kabla, vifaa, na components zingine zinazopatikana katika underground power distribution systems. Placement sahihi, voltage selection, na coordination na riser pole arresters can significantly enhance protective margins na minimize damaging surge voltages. Applications typical zinajumuisha installing arresters at the end of a radial system au at both ends of an open point on a loop system, with additional arresters added at strategic upstream locations for optimal protection.

• Fused Elbows: Hizi zinajumuisha replaceable current-limiting fuses for current protection in OH/OG cable terminations na 200 A separable connector interfaces for compatibility with other Elastimold accessories.

Raychem ni brand nyingine maarufu katika field ya cable splicing na termination equipment.

Terminations for GIS (Gas Insulated Substations)

Wakati space available kwa installation ya substation ni chache au mazingira ni extremely harsh, GIS (Gas Insulated Substation) ni solution inayopendekezwa zaidi. GIS ni assembly ya multi-component ya chache, iliyohifadhiwa katika grounded metallic enclosure. Ina bus bars, circuit breakers, isolators, na instrument transformers, na compressed sulfur hexafluoride (SF6) gas serving as the primary insulation medium, ensuring reliable phase-to-ground insulation. Ingawa GIS zinapatikana zaidi indoor, models za outdoor pia zipo.

GIS units zina enclosures za cable termination ambazo terminations za kabla zinapatikana. According to IEC Standard 60859, both the enclosures and cable terminations must meet specific dimension requirements to ensure interchangeability. Cable terminations for GIS are suitable for gas, oil-paper, na XLPE-insulated kabla na share many components with the cable joints previously discussed.

Features of GIS Cable Terminations

The main features of GIS cable terminations include:

• Cable Lug: Facilitates the connection between the cable conductor and the termination.

• Box Body: Typically made of aluminium alloy or a similar material, providing structural support and protection.

• Reliable Support Insulator: High-grade, non-tracking epoxy insulators offer excellent mechanical and electrical properties. These insulators are compatible with SF6 gas by-products, ensuring a long service life for the termination. Their design also allows for an optional cable shield break.

• Filling Compound: Such as transformer oil, polybutene oil, or similar substances, which help in insulation and stress relief.

• Stress Control Cone with Bundle Tape: Manages electrical stress at the cable insulation-termination interface.

• Rigid Cable Support: The connector is securely locked in place by a threaded hood at the top of the support insulator. This design ensures that the electrical connection between the GIS and the termination is not subjected to mechanical forces from the cable.

• Positive Sealing System: A double "O" ring sealing system is employed to seal the termination oil compartment from the GIS SF6 compartment. Fully retained gaskets are compressed to prevent the ingress of atmospheric elements into the termination interior.

• Earthing Clamp: Provides a secure connection for earthing purposes.

Figure 4 illustrates a schematic of a GIS cable termination. Some models available on the market do not require the use of oil, eliminating the need for an oil housing.

Sealing, Connection, and Installation Requirements for GIS Cable Terminations

Sealing System

The sealing system of GIS cable terminations is of paramount importance and must be meticulously designed. Its primary function is to prevent the leakage of oil or gas into the GIS. A compromised seal could lead to insulation failures, gas loss, and potential safety hazards. By ensuring a robust and reliable sealing mechanism, the integrity of the GIS environment and the overall electrical system is maintained.

Mating Connection Piece

The GIS supplier is responsible for providing a mating connection piece that is specifically designed to be fitted to the cable end. This component is crucial for establishing a secure and electrical connection between the cable and the GIS. The precise design and compatibility of the mating connection piece are essential to ensure seamless integration and optimal performance of the cable-GIS interface.

Isolation and Testing Facilities

To guarantee the safety and reliability of the electrical system, proper facilities must be provided to safely isolate a feeder cable. This isolation capability is necessary during maintenance, repairs, or fault-finding operations. Additionally, provisions should be made to connect a high-voltage test cable to either the GIS or the cable itself. These testing facilities enable routine inspections and diagnostic tests to assess the condition of the cable and the GIS, helping to identify potential issues before they escalate into major problems.

Required Tools and Accessories for GIS Termination Installation

For the successful installation of GIS cable terminations, a specific set of proper tools and accessories is indispensable:

• Panduit Pliers: These pliers are specifically designed for installing bundle tape around the stress cone. The accurate application of the bundle tape is crucial for managing electrical stress and ensuring the long-term reliability of the termination.

• Circlip Pliers: Used for the installation of the top fitting, circlip pliers provide the necessary grip and precision to secure this important component in place.

• Adapter Flange: The adapter flange plays a key role in facilitating the connection between different components, ensuring a proper fit and alignment within the GIS termination system.

• Top Fitting Removal Kit: This kit is essential for maintenance and repair operations, allowing for the safe and efficient removal of the top fitting when required.

• Re-assembly Kit: The re-assembly kit contains all the necessary components and hardware to put the termination back together after maintenance or repairs, ensuring that all parts are replaced correctly.

• Earthing Kit: An earthing kit is vital for establishing a secure electrical connection to the ground, which is essential for the safety of the electrical system and personnel.

• Screen Connection: The screen connection ensures the proper grounding and shielding of the cable, reducing electromagnetic interference and enhancing the overall performance of the cable-GIS system.