**A. Definition of energy efficiency**

Efficiency is the ratio of mechanical energy output divided by

the electrical energy input. There are different efficiency definitions

that describe the relationship between a motor’s rating and

efficiency test results:

- Tested. This refers to the efficiency measured by testing that

specific motor.

- Nominal or Average Expected. Nominal values are the average

values obtained after testing a sample population of the motor model.

- Nameplate. This refers to the efficiency measured by a specific

standard.

- Minimum. These values are intended to represent the lowest point in

the bell curve of motor efficiency distribution.

- Apparent Efficiency. This is the product of a motor’s efficiency and

power factor.

Figure 2.1 – Typical energy flow of standard motors

Energy losses are the determining factor in motor

efficiency. These losses can be divided in five classes:

Classes of Motor Energy Losses

**B. Motor Losses**Energy losses are the determining factor in motor

efficiency. These losses can be divided in five classes:

Classes of Motor Energy Losses

The main difference between the standards emerges

from the way in which the additional load losses, is

treated. The IEC 34.2 standard assumes a standard value

for the additional load losses at rated load of 0.5% of the

input power. The new proposed IEC 61972 standard

gives two possibilities for the assessment of the

additional losses. The first one is a determination by

means of the measured output power, as in the IEEE 112-

B; the second one gives a fixed amount to every machine

of the same rated power. The Japanese JEC standard 37

completely neglects the additional load losses.

from the way in which the additional load losses, is

treated. The IEC 34.2 standard assumes a standard value

for the additional load losses at rated load of 0.5% of the

input power. The new proposed IEC 61972 standard

gives two possibilities for the assessment of the

additional losses. The first one is a determination by

means of the measured output power, as in the IEEE 112-

B; the second one gives a fixed amount to every machine

of the same rated power. The Japanese JEC standard 37

completely neglects the additional load losses.

**Source**

http://www.icrepq.com/icrepq-08/352-mantilla.pdf

**Paper**

**Genetic Algorithms in Induction Motor Efficiency**

**Determination**

Many current techniques of calculating induction motor efficiency

are difficult, expensive, or inaccurate in the field. Induction motors

consume a large percentage of the electricity used in the US.

Accurate calculations of the efficiency of these motors would allow

savings in both energy and cost. One major obstacle in the

calculation of efficiency is that it is often difficult to measure the

output power accurately and safely while the motor is running,

say in a factory. It would be of interest to find a way to estimate

the output power using only easily measured quantities, such as

input current and voltage.

More

More

**Effective Estimation of Induction Motor Field Efficiency****Based**

**on On-site Measurements**

**ABSTRACT**

This paper proposes the effective technique for

estimating efficiency of existing three-phase induction

motors in the field. This technique focuses on the

operating efficiency of motors without the need for

removing the motors and without the need for measuring

the output power or torque. This paper describes the use

of a few sets of data (voltage, current, power, speed)

measured from the motor (on-site) coupled with the

genetic algorithms for evaluating the motor parameters

instead of using the no-load and blocked rotor test results.

Once these parameters are known it is possible to obtain

the estimated efficiency of the motor. To illustrate how

well the estimated efficiency match that of the calculated

obtained from the standard evaluations, the results of

various induction motors rating 10 up to 100 hp are

presented. Test results indicate that this proposed

technique has a high accuracy, and then it could be

suitable for conducting on-site energy audits of existing

motors in order to support a decision to replace operating

motors with a higher-efficiency model.