Factors Affecting Thermal Limit Power P(to)
Corrected limit Thermal Power P(tc)
P(tc) = P(to) x ft x fa x fu x fl
ta being Ambient temperature
| ta | 10° | 15° | 20° | 25° | 30° |
|---|---|---|---|---|---|
| ft | 1.30 | 1.23 | 1.15 | 1.08 | 1.00 |
| ta | 35° | 40° | 45° | 50° | 55° |
| ft | 0.92 | 0.84 | 0.76 | 0.68 | 0.60 |
fa = 1 for Non Ventilated Gearbox
fa = 1.4 for Gearbox with Ventilation
Duty factor – fu
Dt being Minutes of Operation in One Hour
| Dt | 10 | 20 | 30 | 40 | 50 | 60 |
|---|---|---|---|---|---|---|
| fu | 1.7 | 1.4 | 1.25 | 1.15 | 1.08 | 1.00 |
fl = 1 for Mineral Oil
fl = 1.1 for Synthetic Oil
fl = 1.4 for Synthetic Oil and Viton Seals