Electrical Motors Efficiency Ratings

NEMA - electrical motor efficiency ratings. The efficiency of an electrical motor is the ratio of mechanical power output to electric power input.

Electrical Motors Efficiency Ratings

The efficiency of an electrical motor is the ratio of mechanical power output to the electric power input.

NEMA has established the following efficiency index standards for electric motors based on NEMA Letter Index ratings.

NEMA Letter IndexNominal Efficiency (%)Minimum Efficiency (%)
A95.0
B95.094.1
C94.193.0
D93.091.7
E91.790.2
F90.288.5
G88.586.5
H86.584.0
K84.081.5
L81.578.5
M78.575.5
N75.572.0
P72.068.0
R68.064.0
S64.059.5
T59.555.0
U55.050.5
V50.546.0
W46.0
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Motor Efficiency-- %