Downstream Ir
100 A
Koruma Koordinasyonu ve Seçicilik Hesaplayıcısı
Belirli bir arıza akımında bir üst ve alt devre kesicinin seçicilik sağlayıp sağlamadığını kontrol edin, kademe marjını görün ve örnek bir zaman-akım karakteristik (TCC) eğrisini inceleyin.
Sonuç
Yükünüzü girin → saniyeler içinde tam bir tasarım ve BOM alın
Örnek çıktıSelectivity at 15.0 kA
PARTIAL ⚠
Downstream trips at 0.01 s · upstream at 0.10 s · margin 0.09 s
Upstream Ir
250 A
Grading margin
0.09 s
Requirement
≥ 0.2 s
TCC curves
Trip-time calculation
| Downstream thermal pick-up | Ir_d = 100 A × 1 = 100 A |
| Downstream instantaneous | Im_d = 100 A × 10 = 1000 A (Isc ≥ Im, instantaneous trip) |
| Upstream thermal pick-up | Ir_u = 250 A × 1 = 250 A |
| Trip time @ Isc | t_down = 0.01 s · t_up = 0.10 s · margin = 0.09 s |
Recommendation
Increase the upstream short-time delay to ≥ 0.21 s (or use an energy-selective / current-limiting combination).
Bill of materials
| Equipment | Spec | Qty | Subtotal |
|---|---|---|---|
| Downstream MCCB | 100 A · Ir 100 A · Im 1000 A (10×) | 1 | POA |
| Upstream ACB/MCCB | 250 A · Ir 250 A · Im 2500 A (10×) · Tsd 0.1 s | 1 | POA |
| Total equipment (switchgear) | POA |
Alçak gerilim devre kesicilerini ve rölelerini kademelendiren, böylece yalnızca arızaya en yakın kesicinin açmasını sağlayan koruma mühendisleri ve şalt tasarımcıları için.
Hesaplayıcıyı kullanın
Çözümlü örnek
Önceden hesaplanmış bir referans örneği (taranabilir — JavaScript gerekmez). Canlı sonuç için yukarıya kendi parametrelerinizi girin.
Örnek 1 — 100 A alt, 250 A üst, 15 kA arıza
Selectivity at 15.0 kA
PARTIAL ⚠
Downstream trips at 0.01 s · upstream at 0.10 s · margin 0.09 s
Downstream Ir
100 A
Upstream Ir
250 A
Grading margin
0.09 s
Requirement
≥ 0.2 s
TCC curves
Trip-time calculation
| Downstream thermal pick-up | Ir_d = 100 A × 1 = 100 A |
| Downstream instantaneous | Im_d = 100 A × 10 = 1000 A (Isc ≥ Im, instantaneous trip) |
| Upstream thermal pick-up | Ir_u = 250 A × 1 = 250 A |
| Trip time @ Isc | t_down = 0.01 s · t_up = 0.10 s · margin = 0.09 s |
Recommendation
Increase the upstream short-time delay to ≥ 0.21 s (or use an energy-selective / current-limiting combination).
Bill of materials
| Equipment | Spec | Qty | Subtotal |
|---|---|---|---|
| Downstream MCCB | 100 A · Ir 100 A · Im 1000 A (10×) | 1 | POA |
| Upstream ACB/MCCB | 250 A · Ir 250 A · Im 2500 A (10×) · Tsd 0.1 s | 1 | POA |
| Total equipment (switchgear) | POA |
Örnek 2 — manyetik örtüşme, 30 kA arıza
Selectivity at 30.0 kA
PARTIAL ⚠
Downstream trips at 0.01 s · upstream at 0.10 s · margin 0.09 s
Downstream Ir
100 A
Upstream Ir
250 A
Grading margin
0.09 s
Requirement
≥ 0.2 s
TCC curves
Trip-time calculation
| Downstream thermal pick-up | Ir_d = 100 A × 1 = 100 A |
| Downstream instantaneous | Im_d = 100 A × 10 = 1000 A (Isc ≥ Im, instantaneous trip) |
| Upstream thermal pick-up | Ir_u = 250 A × 1 = 250 A |
| Trip time @ Isc | t_down = 0.01 s · t_up = 0.10 s · margin = 0.09 s |
Recommendation
Increase the upstream short-time delay to ≥ 0.21 s (or use an energy-selective / current-limiting combination).
Bill of materials
| Equipment | Spec | Qty | Subtotal |
|---|---|---|---|
| Downstream MCCB | 100 A · Ir 100 A · Im 1000 A (10×) | 1 | POA |
| Upstream ACB/MCCB | 250 A · Ir 250 A · Im 1250 A (5×) · Tsd 0.1 s | 1 | POA |
| Total equipment (switchgear) | POA |
Nasıl hesaplandı
- · Termik eşik: Ir = In × tr.
- · Anlık eşik: Im = In × im.
- · Ters zamanlı açma (termik bölge): t = 36 · T6 ÷ (I ÷ Ir)².
- · Isc'de alt açma: Isc ≥ Im ise anlık 0.01 s, aksi halde termik süre.
- · Seçicilik: kademe marjı = t_up − t_down ≥ 0.2 s (tam seçicilik).
Referans alınan standartlar
| Standard | Scope |
|---|---|
| IEC 60947-2 | Alçak gerilim şalt ve kontrol düzenleri — devre kesiciler |
| IEEE 242 | Endüstriyel ve ticari güç sistemlerinin korunması ve koordinasyonu için önerilen uygulama (Buff Book) |
| IEC 60255-151 | Ölçüm röleleri ve koruma ekipmanları — aşırı/alt akım koruması |
| GB/T 14048.2 | Alçak gerilim şalt ve kontrol düzenleri — devre kesiciler |
Sıkça sorulan sorular
What is protection coordination and selectivity?
Coordination ensures the breaker closest to a fault trips first, so a downstream fault does not de-energize the whole feeder. Selectivity is achieved by time grading (upstream breaker delays) or current grading. The calculator checks the grading margin between series breakers and plots TCC curves.
What grading margin should I maintain between breakers?
Keep a time grading margin of 0.2-0.4 s between upstream and downstream breakers so the downstream clears first. The upstream trip time must exceed the downstream clearing time plus a safety margin covering breaker tolerance and relay error. The calculator checks this margin on the TCC curves.
What does a TCC curve show?
A time-current characteristic (TCC) curve plots trip time versus Fault Current for a protection device. Plotting upstream and downstream TCCs on one graph shows whether they are selective — the downstream curve must stay left of (below) the upstream curve across the fault range. The calculator renders the curves for the configured devices.
How do I coordinate a fuse with a breaker?
The fuse must clear faster than the breaker upstream for faults above the crossover current, and the breaker must protect for lower currents. Coordination is checked on the TCC plot — the fuse curve stays below the breaker curve up to the maximum fault level. The calculator compares the two characteristics.
What protection does a transformer feeder need?
A Transformer feeder needs overcurrent (50/51), earth fault (50N/51N), and for MV transformers, differential (87) and restricted earth fault for larger units, plus overload (49). The calculator focuses on the overcurrent and earth-fault grading between the feeder and downstream breakers.
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İlgili araçlar
VerificationKısa Devre HesaplayıcısıDesignDağıtım Sistemi HesaplayıcısıVerificationYG Kısa Devre Hesaplayıcısı
Sonuçlar ön tasarım ve referans amaçlı mühendislik tahminleridir. Satın alma veya kurulumdan önce her zaman geçerli standartlarla, ekipman etiketiyle ve yetkili bir mühendisle doğrulayın.
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