How to Read a Marathon Motor Nameplate

The full-load speed of a motor is the speed at which it can run at full load when it is at its rated voltage and load. It is less than the synchronous speed and varies by motor type. For example, a four-pole 60 Hz fractional horsepower motor has a synchronous speed of 1800 RPM, but its nominal full-load speed is 1715 to 1745 RPM.

Full-load speed is the power factor

Full-load torque is required to produce rated horsepower at full load, divided by full-load speed. For example, if the motor is rated at 1 hp, the full-load torque would equal 1.5 hp/kW.

Duty/Time rating is the efficiency

Efficiency is measured as output power divided by the input power. This rating is usually displayed as a percentage. Manufacturers generally guarantee their motor’s reverse osmosis faucet meets efficiency standards within a specified tolerance range. The duty cycle is the maximum time the motor can carry a load without compromising efficiency. Marathon motor nameplates display the duty cycle as “S1” or “Cont”.

Motor nameplates also provide the rated voltage and frequency. If the input voltage and frequency are different, the performance of the motor will be impacted. Input frequencies are usually 50 or 60 Hz. Alternatively, depending on the manufacturer, they can be expressed as three-phase or single-phase.

Enclosure classifies a motor

A Marathon motor nameplate can be categorized by its enclosure, frame size, NEMA design letter, full-load efficiency, and power factor. The nameplate may also include other information, such as a manufacturer serial number or bearing identification number. The data listed on a Marathon motor nameplate may vary, depending on the motor design.

Temperature ratings are also indicated on the nameplate of the motor. They are usually rated for temperatures up to 40degC. For larger motors, the temperature rating may be 60degC. Motors rated for these temperatures have a tolerance at the rated temperature, usually below the autoignition temperature. NEMA considers 40degC as the default ambient temperature.

Model (MOD) or Catalog (CAT) number

The Model (MOD) Catalog (CAT), or serial number on the nameplate of a Marathon motor, is critical for the operation of the motor. It contains critical specifications and information about the motor, including the voltage and frequency of the line voltage. The nameplate can be laser-etched, sticker or metal piece bolted to the motor. If the nameplate has been lost or damaged, there are several steps you can take to determine the motor’s characteristics.

The Model (MOD) or Catalog (CAT) number on a marathon motor nameplate must be following NEMA guidelines. It must also include specific data and other information to aid installation, operation, and maintenance. The style of the nameplate depends on the manufacturer.