Page 567 of 567
05/08
Application Manual for NEMA Motors
Reduction Factors for Ambient Temperature and Altitude
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)
1000
1500
2000
2500
3000
3500
4000
30°C
1.06
1.03
1.00
0.95
0.91
0.87
0.82
35°C
1.03
1.00
0.97
0.93
0.89
0.84
0.79
Ambient Temperature
40°C
45°C
50°C
1.00
0.96
0.92
0.97
0.93
0.89
0.94
0.90
0.86
0.90
0.86
0.83
0.86
0.83
0.79
0.82
0.79
0.75
0.77
0.74
0.71
55°C
0.87
0.84
0.82
0.78
0.75
0.71
0.67
60°C
0.82
0.80
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 1
Horsepowers greater than 200
Explosion Proof motors
Variable Speed Operation
Operating within the Service Factor
Examples:
Calculated HP @ ambient & altitude = BHP / Reduction Factor
#1: Site Ambient (°C)
Site Altitude (m)
Reduction Factor (Table 1)
Brake Horsepower (BHP)
Calculated HP @ amb.& alt.
Motor HP Selection
50
2000
0.86
25
29.1
30
#3: Site Ambient (°C)
Site Altitude (m)
Reduction Factor (Table 1)
Brake Horsepower (BHP)
Calculated HP @ amb. & alt.
Motor HP Selection
35
2000
0.97
55
56.7
60
#2: Site Ambient (°C)
55
Site Altitude (m)
3500
Reduction Factor (Table 1) 0.71
Brake Horsepower (BHP)
130
Calculated HP @ amb. & alt.183.1
Motor HP Selection
200
#4: Site Ambient (°C)
Site Altitude (m)
Reduction Factor (Table 1)
Brake Horsepower (BHP)
Calculated HP @ amb. & alt.
Motor HP Selection
30
4000
0.82
7
8.5
10