Sut Ap Dien Cho Thiet Bi Ho Boi: Bom, Bom Nhiet Va Lap Ke Hoach NEC 680
Khu thiet bi ho boi thuong o xa tu dien chinh, nhung lai tap trung nhung tai de lo ra viec chon day qua nho: dong co, tu dong hoa, gia nhiet va moi truong ngoai troi an mon. Mot mach co the dung ve dong cho phep nhung van gay khoi dong kem, loi dieu khien hoac den mo neu khoang cach dai.
Quy trinh thuc te rat ro rang. Dau tien xac dinh dong thuc te cua nhanh hoac feeder, tach tai dong co 240 V khoi tai dieu khien 120 V, roi kiem tra sut ap truoc khi lap dat xong. Trong cong trinh NEC thuong gap 680.21, 680.25 va 680.26. Trong cong trinh IEC, IEC 60364-7-702 va IEC 60364-5-52 la tham chieu huu ich. NEC IEC
Vi sao mach ho boi can hon ca ampacity
Bom ho boi va may nen cua bom nhiet la tai dong co, vi vay sut ap du thua se the hien truoc o kha nang khoi dong va nhiet do cuon day.
Bang tu dong hoa, bo tao clo muoi va driver LED co the reset ngay ca khi bom van co ve dang chay.
Khu thiet bi ngoai troi ket hop duong day dai, do am va nhieu mach, vi the can xem sut ap cung voi bonding.
Mach bom 240 V co the van chap nhan duoc nhung mach dieu khien hoac o cam 120 V tren cung khu da gan het du phong dien ap.
Nhung diem code va tieu chuan nen ghi tren ban ve
- NEC 680.21: dong co bom ho boi can dung phuong phap di day cua nhanh mach va thuong can kiem tra GFCI, ngat cach ly.
- NEC 680.25: feeder den tu dien ho boi hoac thiet bi ngoai troi can cau hinh day va day tiep dia thiet bi dung.
- NEC 680.26: bonding dong the khong sua sut ap, nhung du an ho boi de phat sinh loi neu tach roi hai van de nay.
- IEC 60364-7-702 va IEC 60364-5-52: truoc khi chot kich co cap cuoi cung phai kiem tra vung ho boi, cach lap dat, he so nhom va muc tieu 3% den 5%.
So sanh nhanh cho cac tuyen ho boi pho bien
Day la cac gia tri lap ke hoach cho day dong va dong tai day du. Chung huu ich de sang loc kich co day truoc khi kiem tra ampacity va huong dan nha san xuat.
| Tinh huong | Khoang cach | Day dan | Sut ap xap xi |
|---|---|---|---|
| Bom ho boi 240 V, 20 A | 140 ft / 43 m | 10 AWG Cu | 2.8% |
| Bom ho boi 240 V, 20 A | 140 ft / 43 m | 8 AWG Cu | 1.8% |
| Tu dong hoa + den 120 V, 8 A | 180 ft / 55 m | 10 AWG Cu | 4.9% |
| Bom nhiet 230 V, 16 A | 45 m | 4 mm2 Cu | 2.6% |
Vi du ho boi co so lieu co the kiem tra lai
Bom ho boi 2 HP, 240 V, 20 A, 140 ft
Voi day dong 10 AWG, sut ap khoang 6.7 V, tuc 2.8% tai 240 V. He thong co the chay duoc nhung du phong cho nhiet do va khoi dong kha it. Tang len 8 AWG se giam con khoang 4.2 V, hay 1.8%, thuong cho kha nang khoi dong tot hon.
Khu tu dong hoa, o cam va den LED, 120 V, 8 A, 180 ft
O khu 120 V, ngay ca dong nho cung co the gay ket qua xau. Voi dong 10 AWG, sut ap khoang 5.9 V, hay 4.9%. Neu len 8 AWG thi con khoang 3.7 V, hay 3.1%, tot hon ro ret cho bo dieu khien va driver LED.
May suoi ho boi bang bom nhiet, 230 V, 16 A, 45 m
O chieu dai 45 m, 2.5 mm2 co the dung duoc trong mot so bo tri, nhung 4 mm2 giu sut ap quanh 6 V, hay 2.6% tai 230 V. Day thuong la lua chon de dang hon khi duong ngoai troi co nhiet do cao va nhom day.
Danh sach hien truong truoc khi lap dat xong
- Tach tinh toan feeder va tung nhanh mach de tong duong dan van nam trong muc tieu.
- Dung chieu dai mot chieu thuc te den khu thiet bi roi cong them chieu dai den tung dong co hoac bo dieu khien.
- Kiem tra huong dan nha san xuat cua bom, bom nhiet, he thong tu dong va he thong muoi truoc khi chot co day.
- Giu bonding, grounding va GFCI trong cung bang tinh voi sut ap.
- Neu tai dieu khien 120 V da gan 3% den 5%, hay tang mot cap day truoc khi be tong va canh quan lam viec sua doi ton kem.
Tinh truoc so lieu ho boi truoc khi keo day
Nhap dong thuc te, dien ap, kich co day, vat lieu va chieu dai mot chieu cho bom, may suoi hoac feeder khu ho boi truoc khi chot ranh va ong.
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