اللائحة الفنية الكويتية   
 KWS  XXX     
 
 
المحركات    الدوارة  -  تصنيفات   الكفاءة   للمحركات  ذات   التيار  
المتردد   
Rotatin g Electrical Machines  - Efficiency Classes of AC Operated 
Motors 
 
 
 
 
الهيئة العامة للصناعة 
دولة الكويت  
-- 
 
1 
  
 
FOREWARD 
The Standard  and Metrology Department represents the National Standardization Body  in the State of 
Kuwait, and it is a founding member of the GCC Standardization Organization,  which is a regional body 
that its membership includes the national standardization bodies of the member states.  
One of the department's tasks is to prepare Kuwaiti standards and technical regulations by specialized 
technical committees.  
The technical sub -committee for Energy Efficiency of Rotary Electric Motors emanating from the 
National Committee for the Electrical and Electronic Standards  Sector has prepared th is Kuwaiti 
technical regulation within the work program of the National Committee for the Electrical and Electronic 
Standards Sector, in accordance with the ministerial decision issued in this regard.  
This  technical  regulation  "Rotating Electrical Machines - Efficiency Classes of AC Operated Motors " was 
based on IEC 60034 -30-1 standard and Saudi technical regulation SASO 2893.  
  -- 
 
2 
 Contents  
1. INTRODUCTION  ................................ ................................ ................................ ................................ ..... 4 
2. TERMINOLOGY  ................................ ................................ ................................ ................................ ..........  4 
2.1 Terms and definitions  ................................ ................................ ................................ ...................  4 
2.1.1 Single -speed motor  ................................ ................................ ................................ ......................  5 
2.1.2 Multi -speed motor  ................................ ................................ ................................ .......................  5 
2.1.3 Variable speed motor  ................................ ................................ ................................ ..................  5 
2.1.4 Brake motor  ................................ ................................ ................................ ................................ . 5 
2.1.5 Geared motor  ................................ ................................ ................................ ...............................  5 
2.1.6 Pump motor  ................................ ................................ ................................ ................................ . 5 
2.1.7 Average efficiency  ................................ ................................ ................................ ........................  5 
2.1.8 Nominal eff iciency  ................................ ................................ ................................ .......................  5 
2.1.9 Rated efficiency  ................................ ................................ ................................ ............................  5 
2.2 Main Symbols  ................................ ................................ ................................ ................................  6 
3. SCOPE  ................................ ................................ ................................ ................................ ........................  7 
3.1 Motors covered in KWS XXX standards  ................................ ................................ ..............................  7 
3.2 Exceptions  ................................ ................................ ................................ ................................ ...........  7 
3.3  Assumptions & Conditions KWS XXX  ................................ ................................ ...........................  8 
4.  Efficiency  ................................ ................................ ................................ ................................ ...............  9 
4.1 Determination  ................................ ................................ ................................ ...............................  9 
4.1.1  General  ................................ ................................ ................................ ................................ .. 9 
4.1.2  Rated Motor Parameters (Voltages, Frequencies and Power)  ................................ .............  9 
4.1.3  Motors Auxiliary Devices  ................................ ................................ ................................ ...........  10 
4.2  Rating  ................................ ................................ ................................ ................................ ...............  11 
4.3 Classification and marking  ................................ ................................ ................................ ..........  11 
4.3.1  General  ................................ ................................ ................................ ................................  11 
4.3.2  Efficiency classification  ................................ ................................ ................................ .......  11 
4.3.3  Motors below IE1 efficiency ................................ ................................ ................................  12 
4.3.4  Marking  ................................ ................................ ................................ ...............................  12 
4.4 Tested limits for efficiency classes IE1, IE2, IE3 and IE4  ................................ ................................ ... 13 
4.4.1 Tested efficiency limit for IE1  ................................ ................................ ................................ ..... 13 
4.4.2 Tested efficiency limit for IE2  ................................ ................................ ................................ ..... 14 -- 
 
3 
 4.4.3 Tested efficiency limit for IE3  ................................ ................................ ................................ ..... 15 
4.4.4 Tested efficiency limit for IE4  ................................ ................................ ................................ ..... 16 
4.4.5 Interpolation of nominal efficiency limits of intermediate rate d powers for 50 Hz mains supply 
frequency  ................................ ................................ ................................ ................................ ............  17 
5. Comparison between different Efficiency classes  ................................ ................................ ..................  19 
6. Registration:  ................................ ................................ ................................ ................................ ........  20 
6.1 General  ................................ ................................ ................................ ................................ ..............  20 
6.2  Type of documents needed for registration under the scope of this standard for registration.  .... 21 
7. Sources  ................................ ................................ ................................ ................................ ................  22 
 
 
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4 
  
1. INTRODUCTION  
 
Electrical motors are used in different applications , such as blowers, fans, 
pumps, etc. Th is standard  can be used for commissioning line operated 
electrical AC motors .  This standard deals with all kinds of electric motors that 
are rated for line operation (including starting at reduced voltage).  This 
includes single -and three -phase low voltage induction motors, as well as line -
start permanent -magnet motors. The efficiency of electric  motor s is based on 
the rated  power . Therefore,  KWS XXX  is applied  to the power range of 0.12 
kW - 375 kW.  All technical constructions of electric motors are covered as 
long as  they are rated for on -line operation and not just three -phase.  
The standard IEC 60034 -30-1 now includes five efficiency level s IE1, IE2, 
IE3, IE4 , and IE5 . IE1 represents the lowest efficiency , and IE5 represent s the 
current highest level of efficiency. The new class IE5 is not yet defined in 
detail . 
In order to achieve a significant market share, it is essential for high -efficiency 
motors to meet Kuwa it energy conservation standard  code (MEW/R -6/2014) 
for rated powers with respect  to mechanical dimensions such as frame -size 
and flanges.  Th is standard defines energy -efficiency classes independent of 
dimensional constraints . It may not be possible in all markets to produce 
motors with higher efficiency classes and maintain the mecha nical dimen sions 
of the Kuwait standards. Combinations of components (such as power drive 
systems) will need a combined efficiency rating.  That rating should not be an 
IE code  in order to avoid confusion.  The efficiency level in this standard for 
50 Hz is  not always entirely consistent across all numbers of poles and over 
the whole power range.  
 
 
2. TERMINOLOGY  
 
2.1 Terms and definitions  
For the purposes of this document, the terms and definitions given in IEC 
60034 -1 and following apply.  
 -- 
 
5 
 2.1.1 Single -speed motor  
Motor rated for 50Hz on -line operation. Single -speed motors may be capable 
of frequency converter operation with variable speed.  
 
2.1.2 Multi -speed  motor  
Motor rated for 50Hz on -line operation that has multiple windings or a 
switchable w inding to provide two or more different number of poles with 
different synchronous speeds.  
 
2.1.3 Variable speed motor  
Motor rated for a speed range and supplied by voltage of variable amplitude 
and frequency  
 
2.1.4 Brake motor  
Motor equipped with an elect ro-mechanical brake unit operating directly on 
the motor shafts  without couplings  
 
 
2.1.5 Geared motor  
Motor equipped with an integral gearbox without couplings ( i.e., the first gear 
wheel is fixed to the motor shaft)  
 
2.1.6 Pump motor  
Motor directly attached to a pump without couplings (i.e. the impeller is fixed 
to the motor shaft)  
 
2.1.7 Average efficiency  
Average  efficiency value for a motor population of the same d esign and rating.  
 
2.1.8 Nominal efficiency  
Efficiency value required to meet a certain efficiency class according to the 
efficiency tables in this standard.  
 
2.1.9 Rated efficiency   
Efficiency value declared by the manufacturer . 
 
 -- 
 
6 
 2.2 Main Symbols  
ƞn is the nominal efficiency, %  
ƞ is the rated efficiency, %  
ƒN is the rated frequency, Hz  
nN is the rated speed, min-1 
PN is the rated power, kW  
TN is the rated torque, Nm  
UN is the rated voltage, V  
 
 
  -- 
 
7 
 3. SCOPE  
 
3.1 Motors  covered in KWS  XXX  standards  
 
KWS XXX  specifies efficiency classes for single -speed electric motors that 
are rated according to IEC 60034 -1 and rated for operation on a sinusoidal 
voltage supply. The scope of the standard, as well as its exceptions, is defined 
in the followi ng Table 1. 
 
Table 1 : General Motors  covered in KWS XXX  standards  
Number of poles  2, 4, 6, 8  
Power range  0.12 – 375 kW  
Efficiency Level  IE1 - Standard Efficiency   
IE2 - High Efficiency   
IE3 - Premium Efficiency   
IE4 - Super Premium Efficiency  
Voltage  < 1000 V, 50 Hz  
Degree of protection  All 
Operating mode  S1 (permanent operation with constant load); motors, 
that are designed for different operating modes but can 
still be operated permanently with rated output.  
Degree of temperature  -20°C - +60°C  
Altitude  Up to 4000 m above sea level  
Geared motors  Yes 
Smoke Extraction Motors with 
a temperature class up to 400°C  Yes 
 
 
 
3.2 Exceptions  
 
• Motors completely integrated into a machine (for example pump, fan and 
compressor) that cannot be practically tested separately from the machine 
even with provision of a temporary end -shield and drive -end bearing.  This 
means the motor shall:  a) share com mon components (apart from connectors 
such as bolts) with the driven unit (for example, a shaft or housing)  and b) not 
be designed in such a way as to enable the motor to be separated from the 
driven unit as an entire motor that can operate independently o f the driven -- 
 
8 
 unit.  That is, for a motor to be excluded from this standard, the process of 
separation shall render the motor inoperative.  
• Single -speed motors with  10 or more poles, as well as motors, that are 
designed for variable speed.  
• Motors with mechan ical commutators (e.g. DC -motors).  
• Motors with integrated frequency converters (compact -drives), if the motor 
cannot be tested separately from the converter. The efficiency -classification 
of compact -drives has to be based on the complete PDS (Power Drive S ystem) 
and therefore has to be defined in a separate norm.  
• Brake motors, if the brake is an integral component of the inner motor -
construction and can be neither removed nor separately operated during the 
testing of motor -efficiency.  
• Submersible motor, whi ch are specifically designed to be operated completely 
immersed in liquid.  
• Smoke Extraction Motors wi th a temperature -class of over 3 00 °C.  
 
3.3  Assumption s & Conditions  KWS XXX  
 
1. The rated efficiency and efficiency classes are based on 25 ◦C ambient 
temperature according to IEC 60034 -2-1. 
2.  This standard establishes a set of limit efficiency values based on frequency, 
number of poles and motor power.  No distinction is made between motor 
technologies, supply voltage or motors with increased insulation designed 
specifically for converter operation even though these motor technologies may 
not all be capable of reaching the higher efficiency classes (See Table 1).  This 
makes different motor technologies fully comparable with respect to their energy 
efficient potential.  
3. Regulators should consider the above constraints when assigning national 
minimum energy - efficiency performance standards (MEPS) with respect to any 
particular type of mo tor. 
4. The efficiency of power -drive systems is not covered by this  standard . In 
particular, motor losses due to harmonic content of the supply voltage, losses in 
cables, filters and frequency -converters, are not covered. Motors with flanges, 
feet and/or sha fts with mechanical dimensions different from IEC 60072 -1 are -- 
 
9 
 covered by this standard. Also  geared motors are covered by this standard 
including those incorporating non -standard shafts and flanges.  
5. Totally enclosed air -over machines (TEAO), i.e. totally e nclosed frame -surface 
cooled machines intended for exterior cooling by a ventilating means external to 
the machine, are covered by this standard.  Efficiency testing of such motors may 
be performed with the fan removed and the cooling provided by an extern al 
blower with a similar airflow rate as the original fan.  
6. A motor is not excluded when the motor and frequency -converter can be 
separated,  and the motor can be tested independently of the converter.  
7. Brake motors with a brake coil that is integrated into t he flange of the motor are 
covered as long as it is possible to test motor efficiency without the losses of the 
brake (for example by dismantling the brake or by energizing the brake coil from 
a separate power source). When the manufacturer offers a motor of the same 
design with and without a brake the test of motor efficiency may be done on a 
motor without the brake.  The determined efficiency may then be used as the 
rating of both motor and brake motor.  
 
 
4.  Efficiency  
4.1 Determination  
4.1.1 General  
 
This standard deals with single speed motors operated on -line.  Motors 
operated by frequency -converters may have higher losses as compared to on -
line (sinusoidal) power supply due to the harmonic voltage content (for details 
see (IEC/TS 60034 -25).  In orde r to make efficiency class ratings comparable 
between different motor technologies, all tests according to this standard shall 
be performed on sinusoidal voltage. Efficiency and losses shall be tested in 
accordance with the preferred method of the individu al motor type as given in 
IEC 60034 -2-1. 
 
4.1.2 Rated Motor Parameters (Voltages, Frequencies and Power)  
 
The rated efficiency shall be determined at rated power P N, rated voltage U N 
and rated frequency f N. Motors rated for an extended voltage tolerance ( 415 
V ± 6 %) shall be assigned a single rated efficiency, i.e. the extended tolerance 
shall be disregarded.  -- 
 
10 
 Motors with rated voltage/frequency combinations of the same magnetic flux 
and power, 2 40 V / 4 15 V (delta -star) or 230 V/460 V (double -star/start), shall 
have only one rated efficiency and efficiency class (IE code). Motors with 
more than one rated voltage/frequency/power combination should be assigned 
a rated efficiency and a rated efficiency -class (IE code) for each rated 
voltage/frequency/power com bination.  
However, as a minimum the lowest efficie ncy value and the associated IE code 
(of all rated voltage/frequency/power combinations) shall always be printe d 
on the rating plate. All  efficiency values and IE codes shall be available in the 
product documentation (catalogue or operating instructions).  
 
4.1.3  Motors  Auxiliary Devices  
 
Most electric motors covered by this standard may be equipped with auxiliary 
devices such as shaft seals, external, mechanical brakes, back -stops and 
unidirectional bearings, speed sensors, tacho -generators in various 
combinations.  
However, as long as thes e auxiliary devices are not an integral part of the basic 
motor design, the determination of efficiency in all possible combinations is 
not practical.  Tests for efficiency of such modified standard motors shall be 
performed on basic with original cooling without auxiliary devices installed.  
 
The losses of a separately driven fan are to be included in the efficiency 
determination procedure when the external fan is an integral part of the basic 
motor construction.  When the external fan is just an optional a dd-on to a mass -
produced motor, which normally carried a shaft -mounted fan, the losses of the 
basic motor (with the shaft -mounted fan) can be used.  
 
Angular -contact bearings (thrust bearings) for vertical mounted motors may 
be replaced by standard bearings  during efficiency testing.  Such motors may 
be tested horizontally.  
 
Some types of motors (such as geared motors, pump motors and others) are 
equipped with shaft seals to prevent ingress of oil or water into the motor.  
External seals shall be removed fo r efficiency testing.  This applies only to 
seals that are accessible from the outside without dismantling of the motor 
(dismantling of the fan -cover and the fan is accepted).  
 
Electro mechanical brakes shall be removed during testing of motor efficiency.   
When the motor construction prohibits a removal of the brake, the brake -coil -- 
 
11 
 shall be energized from a separate power source and the energy consumption 
of the brake -coil shall be disregarded in the calculation of motor efficiency.  
 
4.2  Rating  
 
The effic iency declared by the manufacturer on the rating plate (rated 
efficiency) shall be greater or equal to the tested efficiency as defined in this 
standard (according to the efficiency class (IE code) on the rating plate).  
 
The full -load efficiency of any motor, when tested at rated voltage and rated 
frequency shall not be less than the rated -/classification efficiency minus the 
tolerance of the total losses in accordance with IEC 60034 -1. 
 
It is recommended to report efficiencies at 50%, 75% and full load in the 
product documentation.  For the purpose of this standard only the efficiency 
at rated power applies.  
 
Variations in materials, manufacturing process and testing result in motor -to-
motor efficiency variations for a given motor design; the full-load efficiency 
for a large population of motors of a single design is not a unique value but 
rather a band of efficiency.  Therefore, the energy efficiency limits given in 
this standard are nominal.  
 
4.3 Classification and marking  
4.3.1 General  
 
The designation of the energy efficiency class consists of the letters “IE” (short 
for International Energy Efficiency class), directly followed by a numeral 
representing the classification according to Table 2.  
 
 
4.3.2 Efficiency classification  
 
The standard defines four IE (International Efficiency) efficiency classes for 
single speed electric motors that are rated according to IEC 60034 -1 or IEC 
60079 -0 (explosive atmospheres) and designed for operation on sinusoidal 
voltage.  
 -- 
 
12 
  
TABLE 2  – Efficiency Classification  
Designation  Definition  
IE1 Motors with a rated full -load efficiency equal to or exceeding the limits listed in 5.4.1.  
IE2 Motors with a rated full -load efficiency equal to or exceeding the limits listed in 5.4.2.  
IE3 Motors with a rated full -load efficiency equal to or exceeding the limits listed in 5.4.3.  
IE4 Motors with a rated full -load efficiency equal to or exceeding the limits listed in 5.4.4.  
 
 
4.3.3 Motors below IE1 efficiency  
 
Some motors have rated efficiencies below the limits given in Tables 3 and 4.  
No marking of these motors shall be required.  
  
4.3.4 Marking  
 
The motors shall be durably marked with the following points , which should be 
mentioned  on the  nameplate : 
1. The manufacture’s name or mark  
2. The original country of manufacture  and the manufactured year  
3. The manufacture’s machine code  
4. The number of phase s 
5. The rated efficiency and the IE code  
6. The class of rating of machine if designed for other than rating for 
continuous running duty system  
7. The rated output or range of rated output in the horsepower  or watt.  
8. The rated voltage or range of rated voltage in volts  
9. The rated frequency or range in Hz 
10.  The rated consumed current or range of rated current in amperes  -- 
 
13 
 11.  The maximum power factors  
12.  The rat ed speed or range  
13.  The power factor  
14.  The maximum  ambient air temperature, if other than 40 oC, Temperature 
rise, and Insulation class  
15.  The altitude for which the machine is designed if exceeding 1000 m above 
sea level.  
16.  Frame size  
17.  IP protection  
18.  Bearing details  
19.  Greasing intervals  
20.  Mounting type  
 
4.4 Tested  limits for efficiency classes IE1, IE2, IE3 and IE4  
 
   4.4.1 Tested  efficiency limit for IE1  
Table 3  – Tested  efficiency limits (%) for 50 Hz IE1  
PN 
kW Number of poles/synchronous speed  
min -1 
2/3000  4/1500  6/1000  8/750  
0.12 45.0 50.0 38.3 31.0 
0.18 52.8 57.0 45.5 38.0 
0.20 54.6 58.5 47.6 39.7 
0.25 58.2 61.5 52.1 43.4 
0.37 63.9 66.0 59.7 49.7 
0.40 64.9 66.8 61.1 50.9 
0.55 69.0 70.0 65.8 56.1 
0.75 72.1 72.1 70.0 61.2 
1.1 75.0 75.0 72.9 66.5 
1.5 77.2 77.2 75.2 70.2 
2.2 79.7 79.7 77.7 74.2 
3 81.5 81.5 79.7 77.0 -- 
 
14 
 4 83.1 83.1 81.4 79.2 
5.5 84.7 84.7 83.1 81.4 
7.5 86.0 86.0 84.7 83.1 
11 87.6 87.6 86.4 85.0 
15 88.7 88.7 87.7 86.2 
18.5 89.3 89.3 88.6 86.9 
22 89.9 89.9 89.2 87.4 
30 90.7 90.7 90.2 88.3 
37 91.2 91.2 90.8 88.8 
45 91.7 91.7 91.4 89.2 
55 92.1 92.1 91.9 89.7 
75 92.7 92.7 92.6 90.3 
90 93.0 93.0 92.9 90.7 
110 93.3 93.3 93.3 91.1 
132 93.5 93.5 93.5 91.5 
160 93.8 93.8 93.8 91.9 
200 94.0 94.0 94.0 92.5 
250 94.0 94.0 94.0 92.5 
315 94.0 94.0 94.0 92.5 
355 94.0 94.0 94.0 92.5 
400 94.0 94.0 94.0 92.5 
 
   4.4.2 Tested  efficiency limit for IE2  
Table 4  – Tested  efficiency limits (%) for 50 Hz IE2  
PN 
kW Number of poles/synchronous speed  
min -1 
2/3000  4/1500  6/1000  8/750  
0.12 53.6 59.1 50.6 39.8 
0.18 60.4 64.7 56.6 45.9 
0.20 61.9 65.9 58.2 47.4 
0.25 64.8 68.5 61.6 50.6 
0.37 69.5 72.7 67.6 56.1 
0.40 70.4 73.5 68.8 57.2 
0.55 74.1 77.1 73.1 61.7 
0.75 77.4 79.6 75.9 66.2 
1.1 79.6 81.4 78.1 70.8 
1.5 81.3 82.8 79.8 74.1 
2.2 83.2 84.3 81.8 77.6 
3 84.6 85.5 83.3 80.0 
4 85.8 86.6 84.6 81.9 -- 
 
15 
 5.5 87.0 87.7 86.0 83.8 
7.5 88.1 88.7 87.2 85.3 
11 89.4 89.8 88.7 86.9 
15 90.3 90.6 89.7 88.0 
18.5 90.9 91.2 90.4 88.6 
22 91.3 91.6 90.9 89.1 
30 92.0 92.3 91.7 89.8 
37 92.5 92.7 92.2 90.3 
45 92.9 93.1 92.7 90.7 
55 93.2 93.5 93.1 91.0 
75 93.8 94.0 93.7 91.6 
90 94.1 94.2 94.0 91.9 
110 94.3 94.5 94.3 92.3 
132 94.6 94.7 94.6 92.6 
160 94.8 94.9 94.8 93.0 
200  up to 1000  95.0 95.1 95.0 93.5 
 
   4.4.3 Tested  efficiency limit for IE3  
Table 5  – Tested  efficiency limits (%) for 50 Hz IE3  
PN 
kW Number of poles/synchronous speed  
min -1 
2/3000  4/1500  6/1000  8/750  
0.12 60.8 64.8 57.7 50.7 
0.18 65.9 69.9 63.9 58.7 
0.20 67.2 71.1 65.4 60.6 
0.25 69.7 73.5 68.6 64.1 
0.37 73.8 77.3 73.5 69.3 
0.40 74.6 78.0 74.4 70.1 
0.55 77.8 80.8 77.2 73.0 
0.75 80.7 82.5 78.9 75.0 
1.1 82.7 84.1 81.0 77.7 
1.5 84.2 85.3 82.5 79.7 
2.2 85.9 86.7 84.3 81.9 
3 87.1 87.7 85.6 83.5 
4 88.1 88.6 86.8 84.8 
5.5 89.2 89.6 88.0 86.2  
7.5 90.1 90.4 89.1 87.3 
11 91.2 91.4 90.3 88.6 
15 91.9 92.1 91.2 89.6 -- 
 
16 
 18.5 82.4 92.6 91.7 90.1 
22 92.7 93.0 92.2 90.6 
30 93.3 93.6 92.9 91.3 
37 93.7 93.9 93.3 91.8 
45 94.0 94.2 93.7 92.2 
55 94.3 94.6 94.1 92.5 
75 94.7 95.0 94.6 93.1 
90 95.0 95.2 94.9 93.4 
110 95.2 95.4 95.1 93.7 
132 95.4 95.6 95.4 94.0 
160 95.6 95.8 95.6 94.3 
200 up to 1000  95.8 96.0 95.8 94.6 
 
   4.4.4 Tested  efficiency limit for IE4  
Table 6  – Tested  efficiency limits (%) for 50 Hz IE4  
PN 
kW Number of poles/synchronous speed  
min -1 
2/3000  4/1500  6/1000  8/750  
0.12 66.5 69.8 64.9 62.3 
0.18 70.8 74.7 70.1 67.2 
0.20 71.9 75.8 71.4 68.4 
0.25 74.3 77.9 74.1 70.8 
0.37 78.1 81.1 78.0 74.3 
0.40 78.9 81.7 78.7 74.9 
0.55 81.5 83.9 80.9 77.0 
0.75 83.5 85.7 82.7 78.4 
1.1 85.2 87.2 84.5 80.8 
1.5 86.5 88.2 85.9 82.6 
2.2 88.0 89.5 87.4 84.5 
3 89.1 90.4 88.6 85.9 
4 90.0 91.1 89.5 87.1 
5.5 90.9 91.9 90.5 88.3 
7.5 91.7 92.6 91.3 89.3 
11 92.6 93.3 92.3 90.4 
15 93.3 93.9 92.9 91.2 
18.5 93.7 94.2 93.4 91.7 
22 94.0 94.5 93.7 92.1 
30 94.5 94.9 94.2 92.7 
37 94.8 95.2 94.5 93.1 
45 95.0 95.4 94.8 93.4 -- 
 
17 
 55 95.3 95.7 95.1 93.7 
75 95.6 96.0 95.4 94.2 
90 95.8 96.1 95.6 94.4 
110 96.0 96.3 95.8 94.7 
132 96.2 96.4 96.0 94.9 
160 96.3 96.6 96.2 95.1 
200 96.5 96.7 96.3 95.4 
250 96.5 96.7 96.5 95.4 
315 up to 1000  96.5 96.7 96.6 95.4 
 
   4.4.5 Interpolation of nominal efficiency limits of intermediate rated powers for 50 Hz 
mains supply frequency  
To determine normative nominal efficiency limits of 50Hz motors with rated 
powers not given in the tables above within the range of 0 .12 kW up to 200 
kW the following formula shall be applied . 
 
Where A . B. C. D = interpolation coefficients (see Tables 8 and 9);  PN is given 
in kW  
The formula and interpolation coefficients were mathematically derived to 
create a best fitting curve for the desired nominal efficiency limits.  They do 
not h ave a physical meaning. The resulting efficiency (%) shall be rounded 
to the nearest tenth . i.e.. XX. X (%) 
 
Table 7–Interpolation coefficients for 0.12 kW up to 0.74 kW 
 
IE code  
Coefficients 8-poles 
 
750/min 6-poles 
 
1000/min 4-poles 
 
1500/min 2-poles 
 
3000/min 
 
 
 
IE1 A 
B 
C 
D 5.9466 
 
7.9458 
 
40.441 
 
66.146 –45.9652 
 
–87.1474 
 
–8.2383 
 
68.7303 16.7271 
 
12.7136 
 
25.947 
 
76.174 11.924 
 
6.3699 
 
30.0509 
 
76.6136 
-- 
 
18 
  
 
 
IE2 A 
B 
C 
D 6.4855 
 
9.4748 
 
36.852 
 
70.762 –15.9218 
 
–30.258 
 
16.6861 
 
79.1838 17.2751 
 
23.978 
 
35.5822 
 
84.9935 22.4864 
 
27.7603 
 
37.8091 
 
82.458 
 
 
 
IE3 A 
B 
C 
D –0.5896 
 
–25.526 
 
4.2884 
 
75.831 –17.361 
 
–44.538 
 
–3.0554 
 
79.1318 7.6356 
 
4.8236 
 
21.0903 
 
86.0998 6.8532 
 
6.2006 
 
25.1317 
 
84.0392 
 
 
 
IE4 A 
B 
C 
D –4.9735 
 
–21.453 
 
2.6653 
 
79.055 –13.0355 
 
–36.9497 
 
–4.3621 
 
82.0009 8.432 
 
2.6888 
 
14.6236 
 
87.6153 –8.8538 
 
–20.3352 
 
8.9002 
 
85.0641 
 
 
Table 8 – Interpo lation coefficients for 0.75 kW up to 200 kW 
 
 
 
IE code  
Coefficients 8-poles 
 
750/min 6-poles 
 
1000/min 4-poles 
 
1500/min 2-poles 
 
3000/min 
 
 
 
IE1 A 
B 
C 
D 2.4433 
 
–13.8 
 
30.656 
 
65.238 0.0786 
 
–3.5838 
 
17.2918 
 
72.2383 0.5234 
 
–5.0499 
 
17.4180 
 
74.3171 0.5234 
 
–5.0499 
 
17.4180 
 
74.3171 
 
 
 
IE2 A 
B 
C 
D 2.1311 
 
–12.029 
 
26.719 
 
69.735 0.0148 
 
–2.4978 
 
13.2470 
 
77.5603 0.0278 
 
–1.9247 
 
10.4395 
 
80.9761 0.2972 
 
–3.3454 
 
13.0651 
 
79.077 
 
 
 
IE3 A 
B 
C 
D 0.7189 
 
–5.1678 
 
15.705 
 
77.074 0.1252 
 
–2.613 
 
11.9963 
 
80.4769 0.0773 
 
–1.8951 
 
9.2984 
 
83.7025 0.3569 
 
–3.3076 
 
11.6108 
 
82.2503 
 
 
 
IE4 A 
B 
C 
D 0.6556 
 
–4.7229 
 
13.977 
 
80.247 0.3598 
 
–3.2107 
 
10.7933 
 
84.107 0.2412 
 
–2.3608 
 
8.446 
 
86.8321 0.34 
 
–3.0479 
 
10.293 
 
84.8208 
 
 
 
 
  -- 
 
19 
 5. Comparison between different Efficiency classes  
 
Table 9 : Minimum efficiency values defined in KWS XXX  based on test methods 
specified in IEC 60034 -1-30:2014 for frequency of 50 Hz  
 
output 
8Pole 6Pole 4Pole 2Pole 8Pole 6Pole 4Pole 2Pole 8Pole 6Pole 4Pole 2Pole 8Pole 6Pole 4Pole 2Pole KW
62.3 64.9 69.8 66.5 50.7 57.7 64.8 60.8 39.8 50.6 59.1 53.6 31.0 38.3 50.0 45.0 0.12
67.2 70.1 74.7 70.8 58.7 63.9 69.9 65.9 45.9 56.6 64.7 60.4 38.0 45.5 57.0 52.8 0.18
68.4 71.4 75.8 71.9 60.6 65.4 71.1 67.2 47.4 58.2 65.9 61.9 39.7 47.6 58.5 54.6 0.20
70.8 7.1 77.9 74.3 64.1 68.6 73.5 69.7 50.6 61.6 68.5 64.8 43.4 52.1 61.5 58.2 0.25
74.3 78.0 81.1 78.1 69.3 73.5 77.3 73.8 56.1 67.6 72.7 69.5 49.7 59.7 66.0 63.9 0.37
74.9 78.7 81.7 78.9 70.1 74.4 78.0 74.6 57.2 68.8 73.5 70.4 50.9 61.1 66.8 64.9 0.40
77.0 80.9 83.9 81.5 73.0 77.2 80.8 77.8 61.7 73.1 77.1 74.1 56.1 65.8 70.0 69.0 0.55
78.4 82.7 85.7 83.5 75.0 78.9 82.5 80.7 66.2 75.9 79.6 77.4 61.2 70.0 72.1 72.1 0.75
80.8 84.5 87.2 85.2 77.7 81.0 84.1 82.7 70.8 78.1 81.4 79.6 66.5 72.9 75.0 75.0 1.1
82.6 85.9 88.2 86.5 79.7 82.5 85.3 84.2 74.1 79.8 82.8 81.3 70.2 75.2 77.2 77.2 1.5
84.5 87.4 89.5 88.0 81.9 84.3 86.7 85.9 77.6 81.8 84.3 83.2 74.2 77.7 79.7 79.7 2.2
85.9 88.6 90.4 89.1 83.5 85.6 87.7 87.1 80.0 83.3 85.5 84.6 77.0 79.7 81.5 81.5 3
87.1 89.5 91.1 90.0 84.8 86.8 88.6 88.1 81.9 84.6 86.6 85.8 79.2 81.4 83.1 83.1 4
88.3 90.5 91.9 90.9 86.2 88.0 89.6 89.2 83.8 86.0 87.7 87.0 81.4 93.1 84.7 84.7 5.5
89.3 91.3 92.6 91.7 87.3 89.1 90.4 90.1 85.3 87.2 88.7 88.1 83.1 84.7 86.0 86.0 7.5
90.4 92.3 93.3 92.6 88.6 90.3 91.4 91.2 86.9 88.7 89.8 89.4 85.0 86.4 87.6 87.6 11
91.2 92.9 93.9 93.3 89.6 91.2 92.1 91.9 88.0 89.7 90.6 90.3 86.2 87.7 88.7 88.7 15
91.7 93.4 94.2 93.7 90.1 91.7 92.6 82.4 88.6 90.4 91.2 90.9 86.9 88.6 89.3 89.3 18.5
92.1 93.7 94.5 94.0 90.6 92.2 93.0 92.7 89.1 90.9 91.6 91.3 87.4 89.2 89.9 89.9 22
92.7 94.2 94.9 94.5 91.3 92.9 93.6 93.3 89.8 91.7 92.3 92.0 88.3 90.2 90.7 90.7 30
93.1 94.5 95.2 94.8 91.8 93.3 93.9 93.7 90.3 92.2 92.7 92.5 88.8 90.8 91.2 91.2 37
93.4 94.8 95.4 95.0 92.2 93.7 94.2 94.0 90.7 92.7 93.1 92.9 89.2 91.4 91.7 91.7 45
93.7 95.1 95.7 95.3 92.5 94.1 94.6 94.3 91.0 93.1 93.5 93.2 89.7 91.9 92.1 92.1 55
94.2 95.4 96.0 95.6 93.1 94.6 95.0 94.7 91.6 93.7 94.0 93.8 90.3 92.6 92.7 92.7 75
94.4 96.1 95.8 93.4 94.9 95.2 95.0 91.9 94.0 94.2 94.1 90.7 92.9 92.9 93.0 93.0 90
94.7 95.8 96.3 96.0 93.7 95.1 95.4 95.2 92.3 94.3 94.5 94.3 91.1 93.3 93.3 93.3 110
94.9 96.0 96.4 96.2 94.0 95.4 95.6 95.4 92.6 94.6 94.7 94.6 91.5 93.5 93.5 93.5 132
95.1 96.2 96.6 96.3 94.3 95.6 95.8 95.6 93.0 94.8 94.9 94.8 91.9 93.8 93.8 93.8 160
95.4 96.3 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 200
95.4 96.5 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 250
95.4 96.6 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 315
95.4 96.6 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 355
95.4 96.6 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 400
95.4 96.6 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 450
500-
95.4 96.6 96.7 96.5 94.6 95.8 96.0 95.8 93.5 95.0 95.1 95.0 92.5 94.0 94.0 94.0 1000IE1 IE2 IE3 IE4-- 
 
20 
  
 
Figure 1: efficiency classes for 4 pole motors at 50 Hz  (Source: ABB)  
 
6. Registration : 
 
6.1 General  
 
Product registration is mandatory if motor is in the scope (including 
exempted motors) of the standard . whereby information about registration 
requirements will be available on the website of the Kuwait  Public Authority 
for Industry . and reference shall be made to the separate registration forms 
and requirements.  
Applications shall be submitted through energy Efficiency registration 
system electronically via the website.  
The applications shall fulfil all updated requirements of the el ectronic 
registration system and any new requirement . procedure . and regulation 
required by the Public Authority for Industry . 
 
 
-- 
 
21 
  
6.2  Type of documents needed for registration under the scope of this standard for 
registration .  
 
• Third party performance test report covering the submitted product   
as per the requirements of this KWS standard (report shall not be older 
than 3 years)  
• Laboratory accreditation (ISO 17025)  with scope of accreditation.  
• Product specification data sheet.  
• Product name plate design.  
• Photos of the product  
 
 
  -- 
 
22 
  
7.  Sources  
 
 Normative References  
 
The following documents . in whole or in part . are normatively referenced in 
this document and are indispensable for its application.  
  
1. IEC 60034 -1. Rotating electrical machines – Part 1: Rating and performance \ 
2. IEC 60034 -2-1. Rotating electrical machines – Part 2 -1: Standard methods for 
determining losses and efficiency from tests (excluding machines for traction 
vehicles).  
3. IEC/TS 60034 -2-3. Rotating electrical machines – Part 23: Specific test 
methods for determining losses and efficiency of converter -fed AC induction 
motors.  
4. IEC60034 -6. Rotating el ectrical machines – Part-6: Methods of cooling (IC 
Code)  
5. IEC/TS 60034 -25. Rotating electrical machines – Part 25: Guidance for the 
design and performance of a.c motors specifically designed for converter supply  
6. IEC 60038 . IECCC standard voltages  
7. IEC 60034 -30-1: 2014 © IEC 2014  
8. IEC 60079 -0. Explosive atmospheres – Part 0: Equipment – General 
requirements  
9. .SASO  2893 Rotating Electrical Machines Part 30 -1: Efficiency classes of line 
operated AC motors (IE code)  
 
 
 
 
 
 
 
 
 
 
 
 
  
  -- 
 
23 
 Bibliography  
 
IEC 60034 -5. Rotating electrical machines – Part 5: Degrees of protection 
provided by the integral design of rotating electrical achiness (IP code) – 
Classification  
 
IEC 60034 -12. Rotating electrical machines – Part 12: Starting performance 
of single -speed three -phase  cage induction motors  
 
IEC/TS 60034 -31:2010 . Rotating electrical machines – Part 31: Selection of 
energy -efficient motors including variable speed applications – Application 
guide  
 
IEC 60072 -1. Dimensions and output series for rotating electrical machines  
– Part 1: Frame numbers 56 to 400 and flange numbers 55 to 1080  
 
ISO 3 . preferred numbers – Series of preferred numbers.  
 
EN 12101 -3. Smoke and heat control system – Part 3: Specification for 
powered smoke and heat exhaust ventilators.  
 
EN 50347 . General purpose three -phase induction motors having standard 
dimensions and outputs – Frame numbers 56 to 315 and flange numbers 65 
to 740  
 
EN 52800 . Energy efficiency for power drive systems . motor starters . power 
electronics and their driven applications  
 
JIS C 4212 (Japanese Industrial Standard) . Low voltage three -phase  
squirrel -cage high efficiency induction motors  
 
NBR 17094 -1. Rotating el ectrical machines – Induction motors – 
Specification  
 
NEMA MG1 . Motors and Generators  
SANS 1804 -1 (South African Standard) . Induction motors – Part 1: IEC 
requirements.  
 
Saudi Standards . Metrology and Quality Organization (SASO)