Understanding motor’s nameplate Motor nameplate is normally located on all produced electric motors. Understanding nameplate information can be hard sometimes, but is essential. In most countries it is a requirement for manufacturers to display all information on the motor’s nameplate, but often this is not the case.
19 Essential Information You Can Find On Motor TemplatesPresentation)
However, when a motor has been in operation for a long time, it is often not possible to determine its operating information because nameplates of motors are often lost or painted over.
Electrical input 1. Voltage This data tells you at which voltage the motor is made to operate. Nameplate-defined parameters for the motor such as power factor, efficiency, torque and current are at rated voltage and frequency. When the motor is used at other voltages than the voltage indicated on the nameplate, its performance will be affected.
2. Frequency Usually for motors, the input frequency is 50 or 60 Hz. If more than one frequency is marked on the nameplate, then other parameters that will differ at different input frequencies have to be indicated on the nameplate as well.
3. Phase This parameter represents the number of AC power lines that supply the motor. Single-phase and three-phase are considered as the standard.
4. Current Current indicated on the nameplate corresponds to the rated power output together with voltage and frequency. Current may deviate from the nameplate amperes if the phases are unbalanced or if the voltage turns out to be lower than indicated.
5. Type Some manufacturers use type to define the motor as single-phase or poly-phase, single-phase or multi-speed or by type of construction. Nevertheless, there are no industry standards for type. Grundfos uses the following type designation: MG90SA2-24FF165-C2.
6. Power factor Power factor is indicated on the nameplate as either “PF” or “P .F” or cos φ . Power factor is an expression of the ratio of active power (W) to apparent power (VA) expressed as a percentage.Numerically expressed, power factor is equal to cosine of the angle of lag of the input current with respect to its voltage.The motor’s nameplate provides you with the power factor for the motor at full-load.Power factor also known as cosFI Mechanical Input //7. kW or horsepowerkW or horsepower (HP) is an expression of the motor’s mechanical output rating – that is it’s ability to deliver the torque needed for the load at rated speed.
8. Full-load speed Full-load speed is the speed at which rated full-load torque is delivered at rated power output. Normally, the full-load speed is given in RPM. This speed is sometimes called slip-speed or actual rotor speed.Motor efficiency label; Full-load speed; Efficiency in percent and kW or horsepower
Performance 9. Efficiency Efficiency is the motor’s output power divided by its input power multiplied by 100. Efficiency is expressed as a percentage. Efficiency is guaranteed by the manufacturer to be within a certain tolerance band, which varies depending on the design standard, eg IEC or NEMA.Therefore, pay attention to guaranteed minimum efficiencies, when you evaluate the motor’s performance.
10. Duty This parameter defines the length of time during which the motor can carry its nameplate rating safely. In many cases, the motor can do it continuously, which is indicated by an S1 or “Cont” on the nameplate. If nothing is indicated on the nameplate, the motor is designed for duty cycle S1.Motor duty
Reliability 11. Insulation class Insulation class (INSUL CLASS) is an expression of the standard classification of the thermal tolerance of the motor winding. Insulation class is a letter designation such as “B” or “F”, depending on the winding’s ability to survive a given operating temperature for a given life. The farther in the alphabet, the better the performance. For instance, a class “F” insulation has a longer nominal life at a given operating temperature than a class “B”.Insulation class. CI.F(B) = class F with temperature rise B
12. Maximum ambient temperature The maximum ambient temperature at which a motor can operate is sometimes indicated on the nameplate. If not the maximum is 40°C for EFF2 motors and normally 60°C for EFF1 motors. The motor can run and still be within the tolerance of the insulation class at the maximum rated temperature. The power output reduction curve shows the performance reduction with increased ambient temperature or increased installation height above sea..
13. Altitude This indication shows the maximum height above sea level at which the motor will remain within its design temperature rise, meeting all other nameplate data.If the altitude is not indicated on the nameplate, the maximum height above sea is 1000 metres.Go back to Index ↑
Construction 14. Enclosure Enclosure classifies a motor as to its degree of protection from its environment and its method of cooling. Enclosure is shown as IP or ENCL on the nameplate.Motor frame, enclosure ,bearing and grease information on nameplate.
15. Frame The frame size data on the nameplate is an important piece of information. It determines mounting dimensions such as the foot hole mounting pattern and the shaft height. The frame size is often a part of the type designation which can be difficult to interpret because special shaft or mounting configurations are used.
16. Bearings Bearings are the component in an AC motor that requires the most maintenance. The information is usually given for both the drive-end (DE) bearing and the bearing opposite the drive-end, non drive- end (NDE).NEMABesides the above mentioned information, NEMA nameplates have some supplementary information. The most important ones are:
Letter code,
Design letter and
Service factor.
17. Letter code A letter code defines the locked rotor current kVA on a per horsepower basis. The letter code consists of letters from A to V. The farther away from the letter code A, the higher the inrush current per horsepower.NEMA code letterLocked rotor kVA/HPNEMA code letterLocked rotor kVA/HP A0 – 3.15L9.0 – 10.0 B3.15 – 3.55M10.0 – 11.2 C3.55 – 4.0N11.2 – 12.5 D4.0 – 4.5ONOT USED E4.5 – 5.0P12.5 – 14.0 F5.0 – 5.6QNOT USED G5.6 – 6.3R14.0 – 16.0 H6.3 – 7.1S16.0 – 18.0 INOT USEDT18.0 – 20.0 J7.1 – 8.0U20.0 – 22.4 K8.0 – 9.0V22.4 AND UP
18. Design letter Design letter covers the characteristics of torque and current of the motor. Design letter (A, B, C or D) defines the different categories. Most motors are design A or B motors. A design A motor torque characteristic is similar to the characteristic of a design B motor; but there is no limit in starting inrush current. With a design B motor, the motor manufacturer has to limit the inrush current on his products to make sure that users can apply their motor starting devices.So, when replacing a motor in an application, it is important to check the design letter, because some manufacturers assign their products with letters that are not considered industry standard which may lead to starting problems.
19. Service factor A motor designed to operate at its nameplate power rating has a service factor of 1.0. This means that the motor can operate at 100% of its rated power.