NEMA Vertical Spec
NEMA Line Vertical Motors Sample Specifications

A. Scope

1.0 This specification provides guidelines for design and manufacture of low vertical squirrel cage induction motors on NEMA-size frames (thru 445 frame).

2.0 Work governed by these specifications includes manufacture, testing and delivery of equipment constructed in accordance with the requirements presented herein.

3.0 Items not addressed by these specifications include, but are not limited to:

3.1 Unloading and installation.

3.2 All external connections.

B. Codes and Standards

1.0 All equipment shall be fabricated, assembled and tested in accordance with the most current applicable standards as defined by the following institutions:

1.1 American National Standards Institute (ANSI).

1.2 Institute of Electrical and Electronic Engineers (IEEE).

1.3 National Electrical Manufacturers’ Association (NEMA).

1.4 Anti-Friction Bearing Manufacturers’ Association (AFBMA).

2.0 All materials and equipment shall be labeled or listed as being approved by the Underwriters Laboratories (U.L.) whenever applicable.

2.1 Equipment offered as meeting the intent of the U.L. requirements may be acceptable subject to the approval of the Purchaser.

C. Conditions of Service

1.0 Motors shall be suitable for continuous operation on a three-phase, (50 or 60) hertz system rated _________volts.  (Not less than 200 volts or more than 600 volts).

2.0 Motors shall be designed to operate at rated load in a maximum ambient temperature of ___ C at a maximum altitude of (1,000 meters is standard).

3.0 The location of installation will be either _______________ as dictated by the specific provisions for each motor.

4.0  All WPI motors shall have a minimum of 1.15 S.F, TEFC (1.0 or 1.15), Explosionproof (1.0 S.F.)

D. Design Requirements

1.0 General

1.1 Motors shall be capable of withstanding all normal forces which may be imposed upon them during the course of normal operation, including starting and normal stops.

1.2 Motors shall be suitable for across-the-line starting and shall be able to start and accelerate the connected load to full load speed with a balanced 90% of rated voltage at the motor terminals.

1.3 Motors shall be capable of continuous operation at full load and rated frequency with a voltage variation of +10%.

1.4 Motors shall be capable of continuous operation at full load and rated voltage with a frequency variation of +5%.

1.5 Motor starting current shall not exceed NEMA Code G for motors 20 H.P. and higher.  Standard NEMA codes for 15 H.P. and lower.  NEMA Design A is allowed for special performance characteristics.

1.6 Motor installation in hostile environments subject to dust, moisture and/or corrosive atmospheric conditions shall have TEFC motors with all parts given protective treatment such as U.S. MOTORS "CORRO-DUTY®" or equal.

1.7  The motor shall be _____ H.P., _____ RPM, _____ Thrust down, _____ Thrust up, _____ Voltage, 3-phase, _____ Hertz, vertical holloshaft, with self-release coupling (non-reverse ratchet, as required), NEMA style P pump base, squirrel -cage induction design.

2.0 Enclosure

2.1 Motors shall be furnished with one of the following enclosure types based on the location of installation and the specific requirements for each motor.

2.1.1 Weather Protected, Type I (WP-I)

2.1.2 Totally Enclosed, Fan Cooled (TEFC)

2.1.3 Totally Enclosed, Class I, Group D, Division 1 Explosion-proof (XP)

2.2 Openings on all Weather Protected designs shall be covered with corrosion resistant metal guard screens having a mesh size no larger than ½ inch square.

2.2.1 Weather Protected Type I motors shall be designed to protect internal components from falling water and debris at angles up to 15 degrees from vertical.

2.3 Enclosures shall be of fabricated steel or cast iron construction in accordance with the manufacturer’s standard design. Canopy caps shall be of aluminum, cast iron, sheet metal or impact resistance plastic and shall be easily removable for maintenance purposes.

2.4 Enclosed motors, to be installed in locations where moisture may collect shall be furnished with drain openings and/or plugs. In the case of Explosion-proof motors, breathers and drains shall be furnished and shall be of the type approved by U.L.

2.5 Lifting eye bolts on 210 frame and larger.

3.0 Mechanical Design

3.1 All rotating parts shall be individually dynamically balanced so that the motor vibration will not exceed 0.0008 inch, maximum vibration amplitude peak to peak.

3.2 Should non-reverse ratchets be specified, reverse rotation shall be limited to 5° maximum.

4.0 Stator Construction

4.1 Stator laminations shall be of fully processed or insulated electrical grade steel.

4.2 Stator windings shall be copper magnet wire. Aluminum magnet wire is not acceptable. Coil extensions shall be blocked and braced sufficiently to minimize movement during normal starting and running conditions at full rated voltage.

4.3 Insulation

4.3.1 Insulation system shall be Class B or better.

4.3.2 Insulation systems shall receive a treatment using a 100% solids resin and moisture resistant systems shall utilize multiple applications on the treatment resin.

4.3.3 When specified, a completely encapsulated insulation system shall be supplied. This system shall be capable of passing the NEMA MG1-27.1 and shall be VPI 2000 Encapsulation (320 fame and higher), or equivalent system.

4.3.4 When specified, motors to be rated for variable frequency drive applications shall meet NEMA MG-1 Part 31 dated 1993 and shall be Inverter Grade® insulation system or equal. The insulation system shall be warranted for a minimum of 3 years operation on VFD power which shall not be limited by maximum cable length restrictions.

4.4 Temperature rise shall not exceed the limits defined by NEMA for Class B insulation system while operating at nameplate horsepower, frequency and voltage (for whatever insulation system provided).

4.4.1 When approved, in the case of a particular rating where Class F temperature is required, motors shall be furnished with Class H or better insulation.

5.0 Rotor Construction

5.1 Rotors shall be of cast or fabricated aluminum in accordance with manufacturer’s standard design.

6.0 Bearings

6.1 Bearings supplied shall be of type and size sufficient to satisfy thrust loading requirements for each motor in accordance with manufacturer’s standard design. Bearings shall be rated for an in-service B-10 life of 8,800 hours.

6.2 Thrust Bearings

6.2.1 Thrust bearings shall be deep-groove ball, angular contact ball or spherical roller type. Special bearings mounted back-to-back or in tandem are acceptable and may be furnished when required according to manufacturer’s standard design. Deep-groove ball bearings shall be used only on normal thrust design motors and shall be capable of handling thrust loads in either direction. High thrust design motors shall be supplied with angular contact ball bearings whenever possible and in accordance with manufacturer’s standard design. Where thrust requirements restrict the use of angular contact bearings, spherical roller bearings shall be furnished.

  • When required, motors furnished with spherical roller bearings shall also be provided with a system of coils in the oil reservoir for the circulation of cooling water.
  • Spherical roller bearings shall be spring loaded to keep the lower bearing race in contact and prevent bearing damage during starting and momentary upthrust conditions.

6.3 Guide Bearings

6.3.1 Guide bearings shall be deep-groove ball type and shall be located at the bottom of the motor.

6.3.2 Guide bearings or bearing assemblies shall be provided with sufficient means for preventing the leakage of lubricant or entrance of foreign matter along the shaft.

6.4 Lubrication

6.4.1 Thrust bearings shall be oil or grease lubricated.  Oil lubricated bearings contained in an oil reservoir shall have an oil sight level gauge and oil fill and drain openings with plugs.

6.4.2 Deep-groove ball bearings furnished as thrust and guide bearings for normal thrust motors shall be grease lubricated. Grease lubricated bearings shall be furnished with provisions for in-service positive lubrication. A drain shall be provided to guard against over lubrication. Smaller motors may be provided with sealed lube for life bearings.

6.4.3 Lubrication instructions attached to each motor at time of shipment.

7.0 Noise Level

7.1 Sound pressure levels shall be measured according to NEMA and shall not exceed 90 decibels as measured on the A-Weighted Scale at a distance of three (3) feet from any motor surface under no load, free field conditions.

8.0 Nameplates

8.1 Motor nameplates shall be of stainless steel and shall be securely fastened to the motor frame with pins of a like material.

8.2 The following information shall be contained on the motor nameplate as a minimum:

8.2.1 Rated Horsepower

8.2.2 Full Load Speed

8.2.3 Frequency

8.2.4 NEMA KVA Code and Design Letter (when applicable)

8.2.5 Rated Voltage

8.2.6 Manufacturer’s Serial Number

8.2.7 Service Factor

8.2.8 Insulation Class

8.2.9 Maximum Ambient

8.2.10 Full Load Current at Nameplate Voltage

8.2.11 Frame Size Designation

9.0 Terminal Boxes

9.1 Terminal boxes shall be of fabricated steel or cast iron construction to be compatible with the motor enclosure specified and when possible, shall be diagonally split and capable of rotation in 90° increments. Boxes not suitable for rotation must be capable of four sided entry.

9.2 The area in which the main terminal box is connected with the motor frame shall be fully gasketed in order to prevent entrance of foreign matter into the motor and to provide support for the stator leads where they pass through the motor frame.   UL explosionproof motors will not have gaskets.

9.3 A properly sized grounding terminal shall be mounted in the main terminal box when specified.

10.0 Leads

10.1 Main motor leads shall have EPDM or equal type jackets and shall be permanently tagged for identification.

E. Accessories

1.0 Space Heaters

1.1 When specified, motors shall be furnished with space heaters to provide sufficient wattage to maintain the internal temperature of the motor at a level approximately 10°C above the ambient temperature while the motor is not in operation.

1.2 Space heaters shall be of the silicone rubber strip type attached directly to the stator end turns. When specified, the leads shall be brought out to an auxiliary terminal box.

1.3 Space heaters shall be rated for operation on a single phase, 60 hertz, 120 volt system.

2.0 Protective Devices

2.1 When specified, stator winding protection shall consist of one or more of the following systems:

2.1.1 Six (6) 120 phm nickel resistance-type temperature detectors (RTD’s) embedded in the stator windings, two (2) per phase. Each detector shall have its leads wired to an auxiliary terminal box.

2.1.2 One (1) positive temperature coefficient (PTC) thermistor temperature sensor embedded in each phase of the stator winding and corresponding solid state electronic control. Thermistor system shall be U.S. MOTORS "THERMA-SENTRY", or equal.

2.1.3 Three (3) bi-metallic thermostats of the automatic reset type, with normally closed contacts, mounted one per phase. Each thermostat shall be furnished with leads suitable for connection to the control circuit.

2.2 When Specified, bearing protection shall consist of one of the following:  (Available for U.S. MOTORS Mod- Max line only (320 - 440 Frame WPI)

2.2.1 Two (2) 120 ohm nickel resistance-type temperature detectors (RTD’s), one (1) per bearing, mounted as closely as possible to the outer surface of each bearing. Each detector shall have its leads wired to a terminal block located in an auxiliary terminal box.

2.2.2 Two (2) bearing temperature relays one (1) per bearing, furnished with indicating scale.

2.2.3 Two (2) dial type thermometers, one (1) per bearing.

2.2.4 Two (2) iron or copper constantan thermo-couples, one (1) per bearing.

F. Testing

1.0 When specified, one (1) motor shall be given a complete initial test in accordance with IEEE 112 method B and shall include the following items:

1.1 Current Balance

1.2 High Potential Test

1.3 Vibration Test

1.4 Winding Resistance

1.5 Locked Rotor Current

1.6 No Load Running Current

1.7 Full Load Heat Run

1.8 Full Load Percent Slip

1.9 Efficiency at 100%, 75% and 50% Load

1.10 Power Factor at 100%, 75% and 50% Load

2.0 When specified, noise test shall be performed in accordance with ANSI S 12.51, ANSI S 12.54 and ANSI S12.55 as referenced in NEMA MG1 Part 9.

3.0 Five (5) copies of certified test reports shall be submitted to the purchaser upon completion of all required tests.

4.0 Purchaser reserves the right to witness any or all of the tests specified to be performed. Prices for this shall be included as a separate item in the seller’s quotation.

G. Submittal Data

1.0 Required with Proposal

1.1 Preliminary Dimension Print and Frame Size

1.2 Approximate Motor Weight

1.3 Complete Motor Nameplate Information

1.4 Motor Performance Data, including the following:

1.4.1 Guaranteed minimum efficiencies at 100%, 75% and 50% of full load.

1.4.2  Average expected efficiencies add 100%, 75% & 50% of full load.

1.4.3 Locked Rotor Current

1.4.4 Full Load Current

1.4.5 Starting Torque

1.4.6 Full Load Torque

1.4.7 Breakdown Torque

1.5 If required long term, job site storage requirements.

2.0 Required within six (6) weeks of Purchase Order Award

2.1 Certified Dimension Prints

2.2 Recommended Spare Parts List Priced

2.3 Connection Diagrams

3.0 Required with motor upon shipment

3.1 Operation and Maintenance Manuals

3.2 Test Reports as Specified

H. Acceptable Manufacturers

1.0 Motors shall be U.S. MOTORS®  brand or approved equal.