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All pump motors have a nameplate, or a permanent adhesive label, that carries critical data about that specific motor. Deciphering that information is vital when specifying a motor to match a pump.

 

A common language is used on nameplates to avoid confusion and help make motors interchangeable between manufacturers. This makes installation, repair, or replacement a safer and more effective operation. The nameplate’s data allows technicians, engineers, and maintenance crews to identify exactly what type of motor they're working with.

 

The amount of nameplate information and layout differ between manufacturers. They all include loads of data. So, we will focus on the most common elements to help you understand what they refer to and what they mean.

 

Most nameplates carry information in a format that meets standards set by either the International Electrotechnical Commission (IEC) or the National Electric Manufacturers Association (NEMA).

 

NEMA is common throughout North America while IEC standards are used in most other parts of the world. 

 

Understanding how to read a pump motor nameplate will help you select the right motor for the right pump in the right application.

 

Frequency is the frequency of input power for which the motor is designed to operate and measured in hertz (Hz). Generally, 60 Hz is used in the U.S. and 50 Hz in many other countries.

 

Frame Size is important for ensuring that a motor will physically fit in a replacement situation. The size conforms to NEMA or IEC standards which should be compatible for a motor being replaced. Motor dimensions include the key dimensions of the motor’s shaft height, face, and bolt hole spacing.

 

Motor Enclosure type keeps the motor from overheating. ODP, Open Drip Proof, motor enclosure has open vents that bring cooler, outside air into the motor to flow directly over the windings. TEFC, Totally Enclosed Fan Cooled, motor has a non-vented enclosure. An external fan is built on the end of the motor with a protective shroud. It blows ambient air across the outside of the motor body. (See ODP vs TEFC)

 

Power is the motor’s rated output power and may be written in kilowatts (kW) or horsepower (hp) indicating its ability to deliver the required torque at rated speed.

 

Voltage represents the rated voltage of the motor. Most motors have a dual low voltage/high voltage rating based on the wiring diagrams. Variations of nameplate voltage can affect motor performance and motor life. A standard motor nameplate is about 4% lower than the common grid rated voltage due to common voltage losses in cable and other equipment feeding the motor. This can affect the motor performance. Higher motor temperature can result from low voltage. Voltage above 10% can cause overheating and affect insulation.

 

Current may be expressed as Full Load Current Amperes (FLA). It is the maximum current that a motor’s windings are designed to handle considering the nameplate’s listed power, voltage, frequency, and speed. It identifies the upper limit that the motor’s insulation can safely sustain without risking damage or reduced lifespan. 

 

Service Factor (SF) is a multiplier that indicates the maximum continuous load the motor can handle under specified conditions. A motor operating continuously at a service factor greater than one will have a reduced life expectancy.

 

Speed/RPM is maximum speed of the motor in revolutions per minute (RPM) without a load present.

 

While the amount of nameplate information varies between manufacturers, they should all include these basic attributes. Use them to guide you to the right motor for your specific application.