Standard Motor Catalog

Section TR Technical Reference Guide

ENCLOSURE: TENV SERVICE FACTOR: 1.0

*NOTE: 47 C is the weighted average temperature rise for XSD Ultra ® Motors, per Ecomagination Product Review (EPR -rev 11-29-2010)

INSULATION CLASS

DUTY CYCLE APPLICATIONS TYPES OF DUTY The duty cycle of a motor describes the energization/ deenergization, and load variations, with respect to time for any given application. Duty cycle applications may be divided into three basic classifications: 1. Continuous duty is a requirement of service that demands operation at an essentially constant load for an indefinitely long time. This is the most common duty classification and accounts for approximately 90% of motor applications. To size a motor for a specific applica tion with this duty cycle classification, select proper horsepower based upon continuous load. 2. Intermittent duty is a requirement of service that demands operation for alternate intervals of load and no-load; or load and rest; or load, no-load and rest; each interval of which is definitely specified. Select a motor for these applications to match the horsepower require ments under loaded condition. In some instances, such as a hoist or elevator application, savings in the purchase price of a motor may be possible by designing for the intermittent duty cycle. 30 or 60 minute motors are normally specified. Frequent starts, however, can increase motor heating. 3. Varying duty is a requirement of service that demands operation at loads and for intervals of time, which may be subject to wide variation. For this classification of duty cycle, a horsepower versus time curve will permit determination of the peak horsepower required and a calculation of the root-mean-square (RMS) horsepower will indicate the proper motor rating from a heating standpoint. The following example demonstrates the method for selecting a motor for a varying duty cycle based upon peak horsepower and RMS horsepower requirements assuming constant frequency.

Figure 15

ENCLOSURE: DRIPPROOF OR TEFC SERVICE FACTOR: 1.15

INSULATION CLASS

TECHNICAL REFERENCE GUIDE

Figure 16

ENCLOSURE XSD ULTRA ® SERVICE FACTOR: 1.0

Figure 18: Duty Cycle Calculations

Figure 17

TR.16

Data subject to change without notice. 03/24 • www.wolongamerica.com