Cikakken Box-type Transformers a Tsakiyar Kirkiro

Prinsip Elektrik da Kaya na Substations Mai Tashin Pad

Shaida shaida elektriki na substation mai tashin pad yana nuna cikin Raisu 1.

Kaya na Bincike:

Substation mai tashin pad na Amurka ta fara da transformer mai tashin pad, kuma ana kawo da kafin kai da kafin gaba:

• Kafin Kai (Wiring Cabinet): Yana da terminal blocks na high/low-voltage, switch na high-voltage load, fuses na plug-in, handle na high-voltage tap changer, gauge na pressure, gauge na oil level, oil thermometer, daban-daban.

• Kafin Gaba (Oil Tank and Radiators): Yana da core, windings, switch na high-voltage load, da fuses na plug-in a cikin tank mai tashi. Turanci body na transformer yana iya zama wound core ko laminated core na cold-rolled grain-oriented silicon steel sheets ko high-efficiency amorphous alloy sheets. Low-voltage windings suke da foil structure, wanda yake tabbatar da resistance na short circuits, lightning impulses, da overloads. Connection group shine Dyn11.

• Sealed Structure: Design na fully sealed na tank yana ba protection. Oil-immersed load switches suna da types masu yawa don in bincika radial ko ring main distribution systems.

Protection da Kaya na Substations Mai Tashin Pad Na Amurka

Substations mai tashin pad na Amurka suna da protection na series connection na backup fuse protector da plug-in fuse. Backup fuse protector yana yi waɗannan ne idan an samu fault a substation mai tashin pad, wanda yake ba hanyar high-voltage line. Plug-in fuse, tun daga dual-sensitive fuses, yana yaɓa idan an samu short-circuit faults, overloads, ko excessive oil temperatures a secondary side. Wani hukumar wannan protection shine economical, reliable, da kuma easy to operate.

High-voltage terminals na substation mai tashin pad suna da bushing sockets, single-pass bushing connectors, da elbow (bent)-type cable connectors wadanda suke da ƙwarewa 200 A. Live parts suna da take-inside insulators, wanda ke nuna fully insulated structure inda surface na terminal ba na electrify, wanda ke ba personal safety. Da kuma, zaka iya sa plug-in composite-insulated metal-oxide arrester a elbow-type insulator bushing. Arrester shine fully shielded, fully insulated, da kuma plug-and-play, wanda ke ba safety da kuma easy installation. Accessories kamar live indicators da fault indicators za su iya zama saki.

Characteristics of Pad-Mounted Transformers

Pad-mounted transformers, wata sabon nau'in transformers da aka yi amfani da su a ranar zuwa, suna da reliable power supply, reasonable structure, rapid and flexible installation, convenient operation, small size, da kuma low cost. Suna iya amfani da su a kan outside da kuma inside, kuma suna da amfani a matsayin manyan scenarios kamar industrial parks, residential communities, commercial centers, da kuma high-rise buildings. Idan a lura da pad-mounted substations na domestic, pad-mounted substations na Amurka suna da abubuwan da ke sama da:

• Compact Size: Volume na biyu yana zama kusan rabi na volume na pad-mounted substations na domestic na same capacity.

• Fully Sealed and Insulated: Daga bane na fully sealed and insulated structure, ba a buƙaci insulation clearances, wanda ke ba personal safety da kuma make them suitable for underground power distribution environments.

• Versatile Application: Suna iya amfani da su a kan ring-main da kuma terminal applications, da convenient conversion, wanda ke tabbatar da power supply reliability.

• Strong Overload Capacity: Suna iya da ƙwarewa 2 times na rated value don 2 hours ko 1.6 times don 7 hours ba tare da hankali akan service life.

• Low Loss: Losses na biyu suna da ƙarin bayan losses na S₉-type transformers na domestic.

• Flexible Cable Connectors: Cable connectors suna da ƙwarewa 200 A load current. A wurare, za su iya yi waɗannan ne as load switches da kuma suke da characteristics na disconnect switches, wanda ke ba convenient and flexible operation.

• Dual-Fuse Protection: Amfani da dual-fuse protection yana ƙara operating costs. Fuses a plug-in fuses suna da dual-sensitive (to temperature and current).

• High-Flash-Point Oil: Amfani da high-flash-point oil (R-TEMP oil with a flash point as high as 312°C), suna iya jirgin da su a kan buildings bace-bace ba da risk na fire hazards.

• Corrosion Resistance: Body na transformer yana da design na anti-corrosion da kuma treated with special paint, wanda ke make it suitable for various harsh environments, kamar areas with frequent storms and high pollution.

• Superior Electrical Performance: Saboda Δ/Υ connection and three-phase five-limb structure, suna da outstanding advantages kamar high voltage quality, stable neutral point, no heating of the body, low noise, da kuma good lightning protection performance.

• Land-Saving: Yana da take-inside green belts, wanda ke save space that would otherwise be used for building power distribution rooms, effectively improving land utilization.

Applications of Pad-Mounted Transformers
Selection of Pad-Mounted Transformers

• Capacity Selection: Determining the capacity involves factors such as load, investment, losses, and service life. Generally, based on meeting the maximum load with a margin, an economic and technical comparison is made among transformers of similar capacities to select the distribution transformer with the lowest total cost of ownership. The rated capacities of American-style pad-mounted substations include 150, 225, 300, 500, 750, 1000, 1500, and 2000 kVA.

• Type Selection: Pad-mounted substations are classified into terminal type and ring-main type, mainly determined by the type of load switch.

• Installation Location: There are two types of insulating oil in pad-mounted substations. One is common mineral oil, such as domestic No. 25 transformer oil; the other is R-TEMP oil (high-flash-point oil with a flash point of 312°C). Pad-mounted substations filled with R-TEMP oil (with a clear mark on the low-voltage side) can be used inside buildings, while those filled with common oil cannot.

• Customization of Low-Voltage Side: American-style pad-mounted substations generally do not come with low-voltage branch protection and metering. However, branch protection switches, metering instruments, and compensation devices can be added on the low-voltage side according to user requirements.

Engineering Application Example

A unit in Kunming urban area, which has newly built residential buildings and office buildings, selected a pad-mounted transformer from American COOPER Company. The transformer model is PMT-LO-500, with a rated capacity of 500 kVA and a rated voltage of 10 kV/0.4 kV. On the low-voltage side, three current transformers, one voltmeter, three ammeters, and four-way load-outlet air switches were added according to the requirements of users and the power supply department. COOPER's fully insulated, maintenance-free cable branching boxes that can withstand any harsh environment and allow load-break plugging and unplugging were installed on both sides of the pad-mounted substation to supply power to each building. The pad-mounted substation and the branching boxes were placed in the green belt, harmonizing well with the environment. After more than a year of operation, both the power supply department and users have reported good results.

Precautions for Use

When selecting and using pad-mounted substations, attention should be paid to the type of pad-mounted substation, the type of load switch, and user requirements for low-voltage meters.

• Types of Pad-mounted Substations: There are ring-main type and terminal type. For ring-main type pad-mounted substations, the load switch can be switched to supply high-voltage power to the other end.

• Types of Load Switches: Load switches are divided into 2-position type, 3-position type, and 4-position type. Each position type has several forms. For example, the 4-position type includes T-type and Y-type, both of which can be used for dual-power supply. The T-type can be used in ring-main pad-mounted substations, while the Y-type can only be used in terminal pad-mounted substations.

• Inspection of Plug-in Fuses in Newly Installed Pad-mounted Substations: When checking the plug-in fuses of newly installed pad-mounted substations, it is necessary to note whether the pressure gauge of the pad-mounted substation indicates zero. If the pressure gauge does not indicate zero, the exhaust valve should be toggled to exhaust air first before plugging or unplugging the fuses. Otherwise, transformer oil may spray out.

Conclusion

Pad-mounted transformers are essential electrical equipment for urban power grid renovation, real-estate development, and residential power supply construction. American-style pad-mounted substations have become the first choice for urban power distribution transformers due to their unique features and prices comparable to domestic counterparts. With their convenient use and numerous advantages, they have received high praise from society and users, and have become the development direction for small-scale urban substations.