How to read the motor’s nameplate data

In this article, we will discuss each parameter mention on a motor’s nameplate. all necessary data printed on motor name plate-like electrical data- voltage, current, frequency, power factor. so here we are going to see how to read motor nameplate

Electrical parameter 

Voltage

This data specifies you at which voltage the motor is manufactured to operate.  Motor 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.

Frequency

Normally, for motors, the input frequency is 50 or 60 Hz. If more than one frequency is marked on the motor nameplate, then other parameters that will differ at different input frequencies have to be indicated on the nameplate as well.

Phase

This parameter represents the number of AC power lines that supply the motor. Single-phase and three-phase are considered as the standard.


Current

Current-Motor-Name-plate-data
Current Motor Name plate

Current indicated on the nameplate corresponds to the rated power output together with voltage and frequency. Current may deviate from the name-plate amperes if the phases are unbalanced or if the voltage turns out to be lower than indicated.

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

Power factor


Power-Factor-Motor-Nameplate
Power Factor- Motor Nameplate

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.

Mechanical Parameter on the motor nameplate 

Mechanical-Data-Motor-Name-plate
Mechanical Data on Motor Nameplate


kW or horsepower

W or horsepower (HP) is an expression of the motor’s mechanical output rating – that is its ability to deliver the torque needed for the load at rated speed.

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.

Performance


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.

Duty

motor nameplate data-Duty
                                              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 name-plate, the motor is designed for duty cycle S1.

Reliability

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”.

Maximum ambient temperature

The maximum ambient temperature at which a motor can operate is sometimes indicated on the nameplate. If 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.

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 meters.

Construction

Enclosure

Enclosure classifies a motor as to its degree of protection from its environment and its method of cooling.  The enclosure is shown as  IP  or  ENCL on the nameplate.

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.

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, nondriver (NDE).

Reference :Grundfos Motor book

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