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Мотор Ток (FLA) Калькулятор | Electrical Мощность Калькулятор

Рассчитать motor full load амперы (FLA)

Phase

Результат

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Формулы

1φI = P / (V × η × PF)

3φI = P / (√3 × V × η × PF)

1 HP = 746 Ватты

Typical Мотор Values

Motor Size	Efficiency	PF
< 1 HP	0.70-0.82	0.65-0.75
1-10 HP	0.82-0.90	0.75-0.85
10-100 HP	0.90-0.95	0.85-0.90
> 100 HP	0.95-0.97	0.88-0.92

Связанные

Understanding Motor Full Load Ток

Full Load Амперы (FLA) is the current a motor draws when operating at its rated horsepower and напряжение. This value is essential for sizing cables, breakers, starters, and overload protection. The motor nameplate FLA is always the most accurate reference.

Key Мотор Ток Values

Full Load Амперы (FLA): Normal operating current at rated load. Use for wire sizing and overload protection.

Locked Rotor Амперы (LRA): Starting current, typically 5-7× FLA. Use for breaker sizing and inrush calculations.

Service Factor Амперы (SFA): Maximum continuous current if motor has service factor > 1.0. SFA = FLA × Service Factor.

Провод and Breaker Размер

Per NEC requirements: Wire ampacity should be at least 125% of motor FLA. Breakers are sized at 175-250% of FLA depending on motor type. Overloads are set at 115-125% of FLA (or SFA if motor has service factor).

Часто задаваемые вопросы

For 3-phase motors: FLA = (HP × 746) / (√3 × V × Efficiency × PF). For single-phase: FLA = (HP × 746) / (V × Efficiency × PF). However, the motor nameplate FLA is always the most accurate source and should be used when available.

Locked Rotor Амперы (LRA) is the current drawn when the motor is energized but rotor is stationary - the initial starting surge. LRA is typically 5-7 times FLA. This high inrush lasts 1-10 seconds depending on motor size and load inertia.

First convert HP to ватты (HP × 746), then divide by напряжение, efficiency, power factor, and phase factor (√3 for 3-phase). Пример: 10 HP at 480V 3-phase with 90% efficiency and 0.85 PF = (10 × 746) / (1.732 × 480 × 0.9 × 0.85) = 11.7 амперы.

Per NEC 430.22, motor branch circuit conductors must have ampacity of at least 125% of motor FLA. Check NEC Table 310.16 for wire ampacity ratings. Also calculate напряжение drop for long runs - keep below 3% to prevent motor overheating.

Per NEC Table 430.52, inverse time breakers for Design B motors should be 250% of FLA. Энергия-efficient motors use 175%. If that size doesn't hold, you can go up to the next standard size but not exceed 400%.

Service Factor (SF) is a multiplier indicating how much a motor can be overloaded continuously. A 10 HP motor with SF 1.15 can run continuously at 11.5 HP. Overloads can be set at SF × FLA instead of just FLA when SF > 1.0.

Motors are constant power devices - they need a certain amount of power to produce rated torque. Since P = V × I, if напряжение drops, current must increase to maintain power. A 10% напряжение drop can increase current by 10-15%, causing overheating.

Higher efficiency motors draw less current for the same mechanical output because less energy is lost as heat. A 95% efficient motor draws about 11% less current than an 85% efficient motor of the same HP rating.