Sample Inverter Duty Motor Specification

1. SCOPE1.1 RequirementsThis specification contains the minimum requirements for the design, manufacture, and testing of ac, polyphase, squirrel cage induction motors. Motors are rated 1/3 to 450 horsepower and 600 volts and below, in NEMA frame sizes 56 through 449T. These motors will provide for constant torque or variable torque applications over a specific speed range when operated from an adjustable frequency drive.

1.2 RestrictionThis specification applies to a motor supplied directly to this purchaser or as part of the electric-motor-driven equipment.

2. STANDARDSU.S.A. The motor shall be designed, constructed, and tested in accordance with all applicable requirements of the latest standards of IEEE, NEMA, ANSI, and with the requirements of the National Electrical Code. (NEC)

CANADA: The motor shall be designed, constructed, and tested in accordance with all applicable requirements of the latest standards of Electro-Federation of Canada (formally EEMAC), Canadian Standards Association (CSA), IEEE, and the Canadian Electrical Code (CEC).

3. MECHANICAL CONSTRUCTION3.1 Enclosure and MaterialsMotors shall be Open Drip Proof; (ODP), Totally Enclosed Fan Cooled; (TEFC), Totally Enclosed Non Ventilated; (TENV) or Totally Enclosed Blower Cooled; (TEBC). TEBC motors shall have a separately driven constant speed blower motor.

Motor frames should be constructed out of extruded aluminum, cast iron, or rolled steel. End brackets must be die cast aluminum with steel bearing inserts, steel with cast iron bearing cartridges, or all cast iron.

3.2 Terminal Boxes (Frames 56-449T)The motor terminal box housing shall be sized to meet NEC requirements in accordance with Tables 430-12(C)(1) and 430-12 (C)(2). The box shall be easily adjusted to accept the input power conduit from the 3,6,9 and 12 o’clock direction. The terminal box shall be stamped steel or cast iron and designed to minimize the entry of contaminants.

3.3 NameplateThe nameplate shall clearly state that the motor is designed for inverter duty application. The nameplate shall be made of mylar or stainless steel and list the following information. Horsepower, full load and maximum sale speed (RPM), NEMA frame size, full load and no load current (amps), service factor, NEMA code letter, bearing identification, nominal full load efficiency, voltage, number of phases, insulation class, time rating, NEMA Design, maximum ambient temperature, full load temperature rise, enclosure, and model number. The nameplate variables shall be printed, stamped or laser etched into the nameplate for permanent reference.

3.4 SEPARATELY DRIVEN BLOWER (TEBC motors only)The separate cooling blower motor shall be totally enclosed, industrial duty and have double shielded or sealed bearings for long life.

3.5 INSULATION SYSTEMThe winding insulation system shall be rated Class F. System components such as slot liners, wedges, and phase separators shall be Class F or class H and the whole insulation system to be of non-hygroscopic materials. Inter-phase insulation paper shall be used.

Triple coat magnet wire or advanced design magnet wire shall be used. Wound stators with insulating materials in position shall be oven baked to drive-off residual moisture, then dipped in Class H varnish and baked again to cure the varnish. A minimum of two dip and bake cycles is required.

The full load temperature rise (of the windings) when the motor is operated on sine wave power shall be measured by resistance and shall be within Class B allowable limits.

The entire insulation system shall be capable of withstanding the 1600V spikes experienced with dV/dt IGBT waveforms as defined in NEMA MG1 –1993, Part 31.

3.6 POWER LEADSAll leads shall be copper stranded wire of the appropriate gauge for the motor rating.

3.7 BEARINGSSingle-row, radial or maximum capacity, deep-groove vacuum-degassed steel ball bearings will be used. The bearing system shall be designed to accept radial and thrust loading and permit motor operation in any position. Ball bearings on direct drive motors shall have AFBMA B-10 minimum life of 40-50,000 hours. The ball bearings shall have an internal clearance equivalent to a Class C3 AFBMA fit.

Ball bearings shall be pre-lubricated and grease reservoirs partially filled with a moisture resistant, rust inhibiting; wide temperature range synthetic based grease. Fittings, when applicable, shall be provided for adding lubricant.

3.8 SHAFT SLINGERThe motor shall have a molded, rotating shaft slinger to help prevent the entrance of contaminants.

3.9 FINISHThe motor shall have an undercoat that withstands degradation by virtually every tough environmental condition. This can be accomplished by using a spray-on primer or an e-coat system where the paint is electrostatically applied. The motor shall be top-coated with an alkyd or acrylic enamel.

3.9.1 HardwareAll hardware shall be plated with a corrosion resistant preventative material.

3.10 BALANCE AND VIBRATIONMotors shall be precision dynamic balanced in accordance with NEMA MG1-1993, Part 7.08.

3.11 WINDINGSThe stator windings shall be 100% copper. There shall be no copper to aluminum connections within the motor.

3.12 Laminations-Stator and RotorStator and rotor laminations shall be manufactured from low core loss steel to minimize eddy current losses and benefit motor operating temperature.

4. PERFORMANCE FEATURES

4.1 Variable TorqueVariable torque motors when applied with open loop adjustable frequency drives shall be suitable for variable toque load profiles continuously between 6 and 60 hertz.

4.2 Constant Torque-Open LoopConstant torque motors when applied with open loop adjustable frequency drives shall be capable of providing at least 150% of rated torque for 1 minute and 100% of rated torque continuously between 6 and 60 hertz.

4.3 Constant Torque-Closed Loop (Vector)Vector motors when applied with open or closed loop flux-vector adjustable frequency drives shall be capable of 150% of rated torque continuously from zero to base speed.

4.4 Speed RangeConstant torque motors shall be capable of constant horsepower operation between base speed and at least 150% of base speed.

4.4 Duty RatingThe motor shall be rated for continuous duty at 40 C ambient (104 F) up to an altitude of 3300 feet (1000 meters).

4.5 Service FactorMotor shall be rated for 1.0 service factor when operated on non-sinusoidal power. Temperature rise (measured by resistance) shall not exceed Class F limits when operated on non-sinusoidal power.

4.6 VoltageMotors in frame sizes 56-405T shall be rated for 230/460/3/60; 444T-449T shall be rated for 460/3/60.

4.7 Motor LeadsAll motor leads shall be clearly marked with the same terminology as shown on the connection diagram.

4.8 Motor NoiseMotor noise shall be measured in accordance with IEEE Std. 85 and shall not exceed the overall sound power level in decibels (A-Weighted) as recommended by NEMA MG1-1993, Part 12.

4.9 Feedback Devices (Constant Torque only)Motors shall have provision for mounting a feedback device directly to the motor end bracket opposite the drive shaft. The coupling shall be a bellows type selected for high torsional rigidity and axial compliance. Feedback leads shall beterminated at a clearly marked terminal strip in a separate terminal box. Mounting feedback device shall not interfere with the performance of the cooling blower.

4.11 Efficiency TestingMotors shall be tested in accordance with NEMA MG1-1993, Part 12, Test Method B.

4.12 WarrantyInverter duty motors shall be warranted against defects in workmanship and materials for a minimum of three years. Feedback devices shall be warranted for at least two years against defects in workmanship and materials.

5. BIDDING INSTRUCTIONSShould the vendor take exception to any of the requirements of this specification, he must so state the exception in his bid and reference the specific item’s paragraph number. The vendor must submit alternate prices for any exception taken to this specification.