Vergûla Berhemên Cihazên Berhemkirina Têkiliyê ya Daxwazanên Danasîna Dağînê
A. Darbendan Binyat
A1. Unit Capacity, Binyayış Metod û Cins
Dar binyayışi darbandan transformeran de, dê tîpan trefa yê sêser û yek ser ê bikar bîn. Transformeran, ya ku tîpa yekser û an trefa sêser be, ji bo capacity yek unit û an terefînên bi capacity yekêm da ku zêdetir 300 kVA be, nebe ku bêt binyayîn lê polê xalîkê yek. Piramerdî yên struktûrî yên taybet nîne ji bo binyayişên polê yek di demê ku capacity yekêm da ku zêdetir 100 kVA be.
Binyayış platform pol (struktûra polê du) nebe bikar bîn ji bilê ku metoda binyayîna din nabe fezîn. Ji bo banked transformers, cluster mounting pirastî ye ji bo cross-arm mounting çünki hêsanere hatine. Lîkewise, cluster mounting û three-phase bracket mounting hewce ne dike ji bo binyayîna surge arresters û cutouts, ji bo ku li gorîyê tayin bike agencîya bikarhênera ku pêşniyar û biniyara transformeran digire.
Şekilên 8-1 û 8-2 metodên binyayîna banked transformers nîşand de. Self-protected transformers fuses yekser primary internal ne ku hewce ne dike bikar bînin ji aliyê personelê taybet. Ji ber vê yek, self-protected transformers ne rekomande.
A2. Cîh
Binyayişan darbandan dikare ji bo çend bin bîn. Di vê mînakên de, transformeran bêt binyayîn lê cîha polê ke dikare têkilî yên load yekêm de. Ji bo span nekin 125 feet, secondary wiring hewce ne dike bigihîje direk lê malên têkilî yên; din, intermediate poles hewce ne.
B. Binyayış Ser Zemîn
B1. Cins û Capacity
Binyayış ser zemîn dikare wek pad-mounted compartmental type û an unit substation type be. Şekil 8-3 binyayiş eksternal pad-mounted compartmental transformer nîşand de.
Karberdena conventional-type (pole-mounted) transformers bi protective devices yekser û secondary nederbas. Ji ber vê yek, binyayişên din hêsanerîn ne, genelî tarîkî werdike, space zêde hewce ne û rare cost savings significant ne derbas jî dikare ku fencing hewce ne.
Pad-mounted compartmental transformers tenê ji bo outdoor bikar bîn, heta ji bo indoor û outdoor design bînin. Unit substation transformers dikare ji bo indoor û outdoor bikar bîn.
B2. Pad-mounted Compartmental Liquid-insulated Transformers
Three-phase pad-mounted compartmental transformers dikare bi ANSI standard sizes derbas heta 2500 kVA, lê nebe bikar bîn ji bo primary voltage piştî 15 kV û ji bo fault current zêde ku standard equipment nederbas îmkanî primary interrupting duty.
Ji bo hilbijêrîn pad-mounted compartmental transformers û unit substations (bi integral û non-integral load-center transformers), factora meyane hewce ne dike li gorîyê: application scenarios, expansion potential, coordination of short-circuit û protective devices, sound engineering judgment, recognized industry practices, û factora meyane li gorîyê operation, maintenance, û reliability:
B3. Residential Power Supply
Pad-mounted transformers typically used for residential û small-scale commercial power supply.
B4. Industrial Power Supply
Pad-mounted transformers can be used for industrial, commercial, û industrial-related applications, provided that the following conditions are met: they supply power to only one building; metering devices û secondary switchgear can be installed within that building; û the coordination requirements for short-circuit û protective devices are fulfilled.
B5. Power Supply for Large Loads
Unit substations û integral and/or non-integral load-center transformers will be used in industrial, large-scale commercial, û institutional applications that involve large loads, power supply to multiple buildings, û the need for secondary busbar protective devices.
B6. Secondary Unit Substations
Secondary unit substations with integral û non-integral outgoing sections should be used. Since neither type is tamper-proof, fencing is required, û the height of the fence should comply with the requirements of the National Electrical Safety Code (NESC). For 480Y/277V power supply systems, transformers with a capacity larger than 1500 kVA should be avoided; for 280Y/120V power supply systems, transformers with a capacity larger than 500 kVA should be avoided, taking into account the magnitude of the secondary fault current.
However, in some cases, it may be more feasible û cost-effective to equip 480Y/277V power supply systems with 2000 kVA transformers û use current-limiting fuses in conjunction with circuit breakers to limit the secondary fault current. The user agency (such as the Host/REQ CMD of the U.S. Air Force) will stipulate the requirements for demand meters.
B7. Location
Outdoor installations are preferred over indoor installations because of lower space costs. However, considering factors such as the length of secondary feeders, indoor installations may be necessary in some cases, û they may be more economically viable.
B7 - 1 Liquid-filled Transformers Installed Outdoors
Outdoor installations shall comply with the National Electrical Code (NEC), MIL-HDBK-1008A, û the National Electrical Safety Code (NESC). The installation location of the transformer shall ensure that in case of a transformer fire, the combustion products will not be drawn into the air intake of the Heating, Ventilation, û Air Conditioning (HVAC) system of adjacent buildings.
The location of pad-mounted transformers shall be in line with the architectural design concept û be protected from vehicular impact. Coordination with the architecture can be achieved by properly planning the relative position to the landscape, planting shrubs around the transformer, û using screened fences. The primary power supply lines for pad-mounted transformers shall be underground. For the secondary connection to the building, underground cables û bus ducts can be used, but no more than six underground cables per phase shall be used in parallel, as overly complex connections may lead to maintenance û space-related issues.
B7 - 2 Liquid-filled Transformers Installed Indoors
Indoor installations shall comply with the National Electrical Code (NEC) û MIL-HDBK-1008A. The transformer vault shall be located on the exterior wall of the building, have vents to the outside, û be accessible only from outside the building under normal design conditions.
The intake fans û louvers of the Heating, Ventilation, û Air Conditioning (HVAC) system shall be interlocked with the smoke detectors û rate-of-rise detectors in the transformer vault û/or related rooms. If a fire occurs in the transformer vault û/or related rooms, these detectors shall de-energize the HVAC air intake. However, if the HVAC air intake is located on the roof of the building û on the opposite side from the transformer vault, such interlocking is not necessary.
Signs shall be posted at the access doors of the transformer vault indicating the appropriate fire-fighting equipment û procedures. Pipes û ducts shall not be routed above indoor transformers.
