Standard Motor Catalog

Section TR Technical Reference Guide

POLYPHASE MOTORS LARGER THAN 500 Hp Rating large than those listed in Tables 6, 7, and 8 are not covered by NEMA design letters, but have minimum torques established by NEMA MG-1 as follows: Table 11: Motor Torque - NEMA MG-1, Part 20

Breakdown torques developed by Design L motors are shown in the following table: Table 12: Single-phase (Design L) Breakdown Torque in lb-ft (NEMA MG-1, Part 10)

Frequency (HZ)

60

50

60

50

60 50

Synchronous Speed 3600 3000 1800 1500 1200 1000

*Minimum % of Rated Full-Load Torque

Torque

Hp

Locked-Rotor

60 60

1 5.16-6.8 6.19-8.2 6.9-9.2 * 1.5 3.6-4.6 4.3-5.5 6.8-10.1 8.2-12.1 9.2-13.8 2 4.6-6.0 5.5-7.2 10.1-13.0 12.1-15.6 13.8-18.0 * 3 6.0-8.6 7.2-10.2 13.0-19.0 15.6-22.8 18.0-25.8 * 5 8.6-13.5 10.2-16.2 19.0-30.0 22.8-36.0 25.8-40.5 * 7.5 13.5-20.0 16.2-24.0 30.0-45.0 36.0-54.0 40.5-60.0 * 10 20.0-27.0 24.0-32.4 45.0-60.0 54.0-72.0 * * * NO torque values have been established for these ratings Maximum locked-rotor currents for Design L, 60 HZ motors are shown in the following table: Table 13: Single-phase Maximum Locked-Rotor Current in Amperes at 230 Volts - NEMA MG-1, Part 12.34 Hp Amps 1 45 1.5 50 2 65 3 90 5 135 7.5 200 10 260 SERVICE FACTOR Service factor is defined as the permissible amount of overload a motor will handle within defined temperature limits. When voltage and frequency are maintained at nameplate rated values the motor may be overloaded up to the horsepower obtained by multiplying the rated horsepower by the service factor shown on the nameplate. However, locked-rotor torque, locked-rotor current and breakdown torque are unchanged. NEMA has defined service factor values for standard polyphase dripproof, 60 HZ motors as shown in the following table: Table 14: Service Factor - NEMA MG-1, Part 12 1.25 1.15* 1.15* 1.15* 1.0 1.0 1.0 1.5-125 1.15* 1.15* 1.15* 1.15* 1.15* 1.15* 1.15* 150 1.15* 1.15* 1.15* 1.15* 1.15* 1.15* 1.0 200 1.15* 1.15* 1.15* 1.15* 1.15* 1.0 1.0 over 200 1.0 1.15* 1.15* 1.15* 1.15* - - Note: Over 250 HP - Synchronous speed may vary after 1800 RPM * These service factor apply only to NEMA design A, B, and C motors. - - Hp Synchronous Speed 3600 1800 1200 900 720 600 514 1

Pull-up

Breakdown 175 * Higher values can be quoted for specific applications.

Locked-rotor current of these designs will normally not exceed 650% of full-load current, and will normally be within NEMA locked-rotor KVA limits for a code G or H motor. SINGLE-PHASE MOTORS

NEMA DESIGN L

TECHNICAL REFERENCE GUIDE

Figure 13: Typical NEMA Design L Speed/Torque Curve

A NEMA Design L motor is a single-phase integral horsepower motor designed to withstand full-voltage starting. The GE offering to meet design limits of design L is a type KC.Starting performance of type KC motors is dependent upon an additional winding controlled by a centrifugal mechanism and switch. Upon energization of the motor, both windings and the run winding of the motor are connected to the line. As the motor comes up to speed, the centrifugal mechanism will actuate and open the switch, removing the start provisions from the line. The RPM at which this occurs is known as “switch speed”. The motor will then operate at full-load with only the run windings connected.

TR.14

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