motor nameplate information #5 – Reliability

This information is useful for troubleshooting and commisioning.It can tell us about the reliability of electric motor.We can design the area or room with such as good ventilation,enough space for maintenance works and suitable with motor application.

This information also can use for safety purpose.we can design the safety working area for that motor and can protect a user or operator from any electric shock or others danger.

The work load is important to ensure the motor can run efficient and not over their capacity.We must design the motor application suitable with working load.

If not the winding of motor cannot hold the high ampere and can cause the winding burn out.It can make higher cost for repairing jobs.

Motor Reliability

Below i explain detail about insulation class,maximum ambient temperature and altitude.

  • Insulation class

Often abbreviated “INSULATION CLASS” on nameplates, it is an industry standard classification of the thermal tolerance of the motor winding. Insulation class is a letter designation such as “A,” “B,” or “F,” depending on the winding’s ability to survive a given operating temperature for a given life. Insulation’s of a letter deeper into the alphabet perform better.

  • Maximum ambient temperature

The nameplate lists the maximum ambient temperature at which the motor can operate and still be within the tolerance of the insulation class at the maximum temperature rise. It is often called “AMB” on the nameplate and is usually given in C.

  • Altitude

This indicates the maximum height above sea level at which the motor will remain within its design temperature rise, meeting all other nameplate data. If the motor operates below this altitude, it will run cooler.

At higher altitudes, the motor would tend to run hotter because the thinner air cannot remove the heat so effectively, and the motor may have to be derated. Not every nameplate has an altitude rating.


  1. hemant says


    can u tell me the reson for high winding temprature in 3.3 kv 910mw motor.


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