Application Manual for NEMA Motors

Reduction Factors for Ambient Temperature and Altitude

30°C 35°C 40°C 45°C 50°C 55°C 60°C1.06 1.03 1.00 0.96 0.92 0.87 0.821.03 1.00 0.97 0.93 0.89 0.84 0.801.00 0.97 0.94 0.90 0.86 0.82 0.770.95 0.93 0.90 0.86 0.83 0.78 0.740.91 0.89 0.86 0.83 0.79 0.75 0.710.87 0.84 0.82 0.79 0.75 0.71 0.670.82 0.79 0.77 0.74 0.71 0.67 0.63

Table 1 - Ambient & Altitude Reduction Factors (see Notes below)

Notes: Applicable only for sinewave operation on motors from 1 to 200 HP.Please contact Siemens for the following cases:

Ambient temperatures or altitudes not listed in Table 1Horsepowers greater than 200Explosion Proof motorsVariable Speed OperationOperating within the Service Factor

Examples: Calculated HP @ ambient & altitude = BHP / Reduction Factor

#1: Site Ambient (°C) 50 #3: Site Ambient (°C) 35Site Altitude (m) 2000 Site Altitude (m) 2000Reduction Factor (Table 1) 0.86 Reduction Factor (Table 1) 0.97Brake Horsepower (BHP) 25 Brake Horsepower (BHP) 55Calculated HP @ amb.& alt. 29.1 Calculated HP @ amb. & alt. 56.7Motor HP Selection 30 Motor HP Selection 60

#2: Site Ambient (°C) 55 #4: Site Ambient (°C) 30Site Altitude (m) 3500 Site Altitude (m) 4000Reduction Factor (Table 1) 0.71 Reduction Factor (Table 1) 0.82Brake Horsepower (BHP) 130 Brake Horsepower (BHP) 7 Calculated HP @ amb. & alt.183.1 Calculated HP @ amb. & alt. 8.5Motor HP Selection 200 Motor HP Selection 10

35004000

1000

Siemens standard motors are designed for operation in a 40°C ambient temperature and 1000m above sea level. For ambient temperatures and altitudes other than 40°C and 1000m, please apply the following factors from Table 1 to your horsepower requirements as shown in the examples below.

Altitude Above Sea Level(meters)

Ambient Temperature

3000

150020002500

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