Section 13 — Electrical

Induction Motors 500 HP and Below

IPE Engineering Practice IPE-EP-13-3-1

Document number: IPE-EP-13-3-1 · Section: 13 — Electrical

1.0 SCOPE

1.1

1.2

1.3

1.4

1.5

This Practice covers requirements for AC integral HP, T frame, polyphase induction motors 1/2 HP to 500 HP. Included as part of this Practice is a Data Sheet (EP 13-3-1 DS) listing

specific equipment requirements. In cases of conflict between the Data Sheet and this Practice, the Data Sheet takes precedence. Explosion proof NEMA motors are covered in EP 13-3-4.

This Practice is appropriate for attachment to an inquiry or purchase document when accompanied by the referenced IPE Engineering Practices and completed Data Sheets.

An Asterisk (*) indicates that a decision by the Owner's Engineer or Owner is required, or that additional information is furnished by the Purchaser.

Any deviation from this Practice must be approved by the procedure described in EP 1-1-3.

A revision bar indicates all changes made to this Revision.

2.0 REFERENCES

All applicable sections of the latest standards and codes listed below are a part of this Practice unless amended herein.

STANDARDS AND PUBLICATIONS

STANDARDS AND PUBLICATIONS (Cont.)

DEFINITIONS

• Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
• Inspector - A Inflection Point Engineering, LLC appointed engineer or inspector.
• Manufacturer -- The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a Manufacturer by a Contractor or the Owner. An indirect order is one issued to a Manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
• Owner - Inflection Point Engineering, LLC.
• Owner's Engineer - A Inflection Point Engineering, LLC appointed engineer.
• Purchaser - The party placing a direct purchase order. The Purchaser is the Owner's designated representative.

SERVICE CONDITIONS

• (*) Motors shall perform satisfactorily when operated indoors or outdoors either intermittently or continuously in environments noted on the Data Sheet. Unless otherwise noted, motors shall be for use in 104°F maximum ambient, -13°F minimum ambient and at an altitude of 3,300 feet or lower.
• (*) When ammonia or H 2S fumes are listed as an environmental condition on the Data Sheet, there shall be no exposed copper (or alloys with free copper) parts. All exposed parts will be corrosion resistant.

DESIGN, CONSTRUCTION AND MATERIALS

• General Requirements
• Design Standards

Motors provided shall be in compliance with IEEE Std. 841-1994 and the requirements of this Practice. Where conflicts arise, the requirements of this Practice shall take precedence.

• Balance and Vibration
• Motor rotors shall be dynamically balanced to 4 W/n oz. inches unbalance ( W= Journal weight pounds; N = maximum continuous running speed rpm). The use of solder or similar deposits for balancing is not acceptable. The use of balance washers is acceptable. Any parent metal removed to achieve dynamic or static balance shall be removed so as not to affect the structural strength of the rotating element.
• All fully assembled 2-, 4-, 6-, or 8-pole motors shall meet the levels of vibration below when tested at no load on elastic mounting per section 12.08 of NEMA MG 1-1993, and when bolted to a heavy, flat base whose natural frequency with motor mounted is removed by at least 25% from the motor frequencies referenced below:
• Motor unfiltered vibration at rated voltage and frequency shall not exceed 0.08 in/s peak velocity for 2-, 4-, and 6-pole machines, and 0.06 in/s peak velocity for 8-pole machines, when measured in any direction on the bearing housing and tested uncoupled with a crowned 1/2 height key in the shaft extension key way.
• Motor filtered vibration at rated voltage and frequency shall not exceed 0.05 in/s peak at frequencies of 2n (twice speed) or 2f (twice frequency).
• Motor unfiltered axial vibration shall not exceed 0.06 in/s peak on bearing housings. This limit shall not apply to roller bearings.
• Bearings, Lubrication and Grease Fittings
• Manufacturers standard anti-friction bearings are acceptable provided they are designed for a minimum L10 life rating (per AFBMA Std 9 and 11) of at least 100,000 hours on horizontal direct connected motors and 40,000 hours for vertical motor applications at rated driven equipment conditions. Horizontal motors in belted operation shall have L10 life rating of at least 17,500 hours.
• Grease used shall be a high quality poly-urea thickened grease with rust and corrosion inhibitors and rated for high temperature operation.
• Bearings shall be regreaseable.
• Horizontal and vertical ball bearing and roller bearing manufacturing tolerance limits shall be in accordance with ANSI/AFBMA 20-1987, table 4 (ABEC1-RBEC1). Ball bearings used in horizontal motors shall have AFBMA C/3 clearances.
• Bearings shall be regreaseable without disassembly of fans or fan covers and shall contain a reservoir equipped with outlet relief devices that extend beyond the fan cover for automatic elimination of purged grease. Front (DE) bearings shall have grease inlet extensions that extend to the top portion of the motor and grease drain/relief extensions with relief devices, that extend at least half way down the motor end bell for easy observance/access of the automatic grease relief. Grease inlet fittings shall be Zirk. Oil- lubricated bearings may be furnished for vertical motors. Inner bearing caps shall be provided such that entry of harmful amounts of oil or grease into the motor interior is prevented.
• For vertical flange mounted motors with thrust loading, angular contact ball (single or duplex type), Conrad deep-groove or spherical roller thrust bearings are recommended, depending on the requirements of the application. Filling-slot (maximum-load) anti-friction bearings shall not be used in any motor. Thrust bearings of other construction shall be noted by the Manufacturer. All vertical motors shall have a top thrust bearing. Where the motor shaft is solidly coupled to the driven apparatus, the thrust capacity of the thrust bearing should be sufficient to carry the weight of the rotating element of the motor and the external axial thrust loads (in either or both directions), as well as the radial load specified.

• Motors in frame sizes 320 and above shall have IP55 protection for both bearings.
• Motor bearing and grease relief design shall allow re-greasing of the motor while it is in operation without damage to the bearing system and minimal entrance of grease into the motor interior. The relief system shall be designed to minimize plugging and insure grease relief under low grease pressure.
• Breathers and Drains

All Motors shall be supplied with corrosion resistant 'T' or labyrinth drains at a low point of the motor frame.

• Coatings
• The inside of motor frames, stator and rotor air gap surfaces shall be sealed with a moisture resistant, long life coating.
• All exterior surfaces including all air flow passages shall have a paint system capable of passing the ASTM B 117-90 test for 96 hours with no paint lifting, and no visible corrosion except at high points of castings.
• Conduit Boxes
• (*) Cast iron conduit boxes as a minimum shall be at least twice the size specified in section

11.06.2 of NEMA MG-1 with a minimum volume of 24 cubic inches. Cast iron conduit boxes for non-explosion proof applications shall be diagonally split; be rotatable in 90° turns; have a threaded conduit opening; have a water seal between the box and the motor frame; and have a gasketed cover. Conduit box orientation shall be as specified on the Data Sheet.

• (*) A separate cast iron conduit box for space heaters is required when space heaters are specified on the Data Sheet.
• A motor lead seal and separator gasket shall be provided between the motor frame and terminal box. The motor leads/frame seal (lead positioning gasket) shall be designed to minimize moisture entrance into the motor and prevent damage to the lead wire insulation.
• Grounding: All motors shall be supplied with a grounding connection lug within the motor terminal box. The lug shall be suitable for the ground wire size as specified in section 11.06.3 of NEMA MG-1. A drilled and tapped hole for a ground lug shall be provided on the motor frame.
• Cooling Fans: The cooling fans shall be made of corrosion resistant, mechanically strong, nonsparking material. When plastic fans are provided they shall be of reinforced thermal setting or thermal plastic material and shall be sufficiently conductive to prevent the accumulation of static charges. Preferably, fans for TEFC motors shall be suitable for rotation in either direction. If a unidirectional fan is used, the rotation of the fan shall be indicated by a permanent, legible stainless steel marker mounted on the motor.
• Enclosures
• Enclosure types shall be severe duty TEFC.
• TEFC (severe duty) enclosures shall be of all cast iron construction including conduit boxes, frame, end brackets, fan covers and mountings.
• Lifting eye bolts or cast hooks shall be furnished with all motors sizes 5 HP and above. Eye bolts shall be located at the balance point. Drilled or tapped holes in the enclosure case shall be dead ended or permanently sealed against water entry.

• (*) When specified on the Data Sheet, the motor shall be equipped with vertical jackscrews appropriately located to facilitate coupling alignment.
• Hardware: All hardware, including frame bolts, conduit box bolts, nameplate fasteners, grease caps or plugs, fan clamp and bolt, drain plugs or fittings, and etc., shall be of corrosion resistant steel and/or plated steel capable of passing the ASTM B117-90 test as outlined in paragraphs A.2, A.3, and A.4 of IEEE Std. 841.
• Insulation, Temperature Rise, Service Factor and Efficiency
• Motors shall have a 1.15 service factor. Motor power rating however, shall be based on a

1.0 service factor and shall have Class F insulation. Credit for service factor shall not be taken when sizing the motor to the driven equipment.

• All motor windings shall be furnished with Class F insulation and not to exceed Class B temperature rise by resistance while operating at rated 1.0 SF loading. Additionally, all motors shall not exceed 90°C rise (Class B service factor temperature rise) by the resistance method at service factor (1.15 SF) loading. The motor shall be rated for continuous operation at full load and service factor load with a 40°C ambient.
• (*) When specified on the Data Sheet all motors shall be provided with a Class B temperature rise by resistance while operating at rated 1.0 SF loading and shall not exceed a Class F temperature rise by the resistance method at 1.15 SF loading for a 40°C ambient.
• The stator sealed winding insulation system for random wound motors above 30 HP shall be applied using multiple dips and bakes with a non-hygroscopic, inorganic varnish (NEMA MG1 - 1.27.2).
• The motor leads shall be of a non-hygroscopic insulation material. EPR or other rubber based insulated wire must have an oil resistant protective jacket such as PVC. Motor leads shall be of a non-wicking material. The motor leads insulation shall be of a thermal rating that equals or exceeds that of the stator windings to allow continuous full service factor loading without lead insulation breakdown.
• All motors covered by this Practice shall be premium efficiency motors exceeding Table 12-10 NEMA MG-1 efficiency levels for energy efficient motors. Guaranteed values shall be based on a 10 percent loss variance from the NEMA nominal (nameplate) efficiency.
• Phase insulation paper in addition to varnish shall be used between the phases of random windings.
• Nameplates
• Nameplates shall be easy to read and made of stainless steel. As a minimum, the nameplates shall contain all the information required by NEMA MG-1 and IEEE Std. 841.
• The nameplate shall include the front and rear (or guide and thrust) bearing numbers in AFBMA nomenclature.
• The nameplate shall also indicate that the motor is incompliance with IEEE Std. 841.
• The motor nameplate shall indicate maximum total temperature rise of stator/rotor at 40°C ambient.
• Noise Levels
• (*) Unless specified otherwise, the maximum dBA (not average) sound pressure level (SPL) generated by the motor shall not exceed 85 dBA at three feet from the motor. Testing and sound measurement location shall be as defined by IEEE Standard 85.
• The Manufacturer shall provide evidence of compliance with noise limits for all proposed motors.

5.2

5.2.1

5.2.2

5.2.3

• The Manufacturer shall quote a standard motor with guaranteed maximum 85 dBA (per IEEE Std. 85) SPL 3 feet from the motor. Guaranteed levels (type test data acceptable) must be furnished (listed) on the Data Sheet. For motors that exceed specified limits, the motor Manufacturer shall separately quote the cost of special designs or acoustic treatment which would provide a guaranteed SPL to that specified. Detail of special designs and/or acoustic treatment shall be furnished with the proposal.

Space Heaters

• (*) When specified on the Data Sheet (Section 21), space heaters shall be arranged to provide the optimum attainable uniform heating of the stator windings.
• Surface sheath temperature of the heater elements or the motor enclosure shall be suitable for the classified area specified on the Data Sheet (Section 21) and shall not exceed 80% of ignition temperatures as specified in NFPA 70 Para. 501-8 (b).
• (*) Space heaters are generally not required and shall only be provided when approved by the Owner and specified on the Data Sheet.

Starting, Reacceleration and Torque

• Motors shall be designed to be capable of accelerating WK 2 per NEMA MG1 -12.44.2 and

12.54 at a rated frequency and 90% rated voltage, with two successive cold or one hot start.

• (*) Torque characteristics shall be in accordance with NEMA Design B or Design C, as specified on the Data Sheets. NEMA Design A motors shall not be supplied.
• Motors 15 HP and larger shall have starting inrush current equal to or less than that specified by NEMA KVA Code G. Motors less than 15 HP shall have the Manufacturer's standard NEMA KVA code letter for the type motor specified.

5.2 Special Applications

Vertical Motors

• (*) The General Requirements of paragraph 5.1 apply. Vertical motors, in general, shall be round frame, P flanged, solid shaft construction. Hollow or special shafts will be completely specified on the Data Sheet, when required.
• Vertical motors shall have a top thrust bearing.
• The top end bracket bearing assembly shall be designed to prevent water from entering the enclosure or shall be fitted with weatherproof hood.
• Bearings shall be selected to give minimum L10 rating life of 40,000 hours (see paragraph 5.1.3) when carrying the maximum loads (radial or axial or both).
• The coupling design shall be taken into consideration for continuous and/or momentary down thrust or up thrust, possible reverse motor drive and pump driving motor backwards.
• Vertical lifting lugs shall be provided.

Two Speed Motors

Two speed motors shall be two winding design, two speed single winding motors are not acceptable.

Adjustable Frequency Drive Applications

(*) When motors supplied in accordance with this practice are to be applied on an adjustable frequency drive (speed) application, the motor Manufacturer shall consult with the Owner to insure that the motor will operate with the specified drive over the specified speed range.

Proper selection of the motor and drive is required to avoid the following conditions:

• Motor rms current exceeding the continuous sinusoidal nameplate rating due to excessive voltage harmonics or improper volt/hertz levels.
• Excessive winding temperature due to insufficient cooling, excessive torque levels, or improper volt/hertz levels; and increased losses due to harmonics.
• Insufficient motor accelerating torque at reduced speeds due to insufficient volt/hertz levels or limitations in the drive's momentary current capacity.
• Increased noise levels due to increased fan noise (above base speed), excitation of mechanical resonances, and/or magnetic noise caused by supply source harmonics.
• Mechanical failure of the motor or coupling due to torque pulsations, operation at or near mechanical resonances, or excess speed.
• Winding failures due to repetitive high-amplitude voltage spikes created by the drive system.
• Damage to the motor and drive due to improper application of power factor correction capacitors.
• Higher motor temperatures which may limit application in Division 2 hazardous areas. Areas of concern shall include, but not be limited to, rotor temperatures as well as stator surface temperature.
• Shaft voltages/current due to harmonics which may cause bearing failure.

TESTING

All tests that require energization of the motor shall be done at the rated frequency and voltage.

• Routine/Commercial Test

Each motor shall be given the following tests to demonstrate that it is free from mechanical and electrical defects. This test shall be conducted in accordance with the latest edition of NEMA MG-1, IEEE Std. 841 and ANSI/IEEE Std 112. Certified test copies shall be provided with each motor. As a minimum this test shall include:

• Measurement of no-load current (each phase), speed and power at rated voltage and frequency.
• A high-potential test in accordance with section 12.03 of NEMA MG-1.
• An insulation resistance test by 500V (minimum) DC megohmmeter.
• Measurement of winding resistance.
• Test of sleeve bearings and oil supply (when furnished). Bracket-type sleeve-bearing test shall consist of a no-load run observation and vibration measurement to ensure bearing operation without excessive noise, heating, or vibration and a check for lubricant leaks. When accessible, the lubrication shall be examined after the run.
• A determination of locked rotor current.
• Vibration test for all motors.
• Complete Test
• (*) When specified on the Data Sheet selected motors shall be given the complete test listed below in addition to the routine test, see paragraph 6.1. This test shall also be in accordance with ANSI/IEEE Std 112. The test shall include:
• The determination of efficiency and power factors at 1/2 load, 3/4 load, full load, and service factor load. ANSI/IEEE Std. 112 method B (Dynamometer test) shall be used to determine motor efficiency.
• The determination of the locked-rotor power factor.
• The measurement of full load current and slip.

• The determination of locked rotor and breakdown torques.
• A heat run at maximum continuous rated service factor.
• Measurement of vibration with motor at rated temperature.
• The motor price and the cost of the complete motor test shall be listed separately.
• List also, the cost of the above complete test as a witness test.
• The test results shall be certified by the Manufacturer and transmitted to the Owner in reproducible form.
• If the efficiency of the motor is found to be less than the guaranteed quoted minimum efficiency the motor will not be accepted by Owner.
• 6.3 Witness Test

(*) When a witness test is specified, the Owner shall witness the entire test of all items detailed on the Data Sheet and other Owner approved purchase documents.

DRAWING AND DATA REQUIREMENTS

• Information To Be Supplied With Quotation
• (*) The drawings and data provided shall fully describe the proposed equipment. The number of copies required will be indicated on the Data Sheet.
• Outline drawings for the motor and for any auxiliary equipment not mounted on the motor shall be provided. Include the weight of each item.
• Provide Representative (Type Test) Performance Data at 40°C ambient and at rated voltage of:
• Full Load RPM
• Motor Current at No Load, 25%, 50%, 75% and 100% Load
• Locked Rotor Current and NEMA Code Letter
• Full Load Torque in lb-ft
• Starting Torque in % of Full Load (Min)
• Breakdown Torque in % of Full Load (Min)
• Guaranteed efficiency at No Load, 25%, 50%, 75% and 100% Load and at Service Factor. Efficiency shall be measured using the Dynamometer Test per ANSI/IEEE Std 112 (Method B).
• Power Factor at No Load, 25%, 50%, 75% and 100% Load and at Service Factor.
• Maximum allowable locked rotor time with winding temperature at rated ambient and with winding temperature at rated rise.
• Noise Level (dbA) measurement at 3 feet.
• The information specified in paragraph 7.1.3 shall be supplied by filling in and returning a copy of the Manufacturer's Section of the motor Data Sheet.
• Identify any exceptions to this Practice.
• Spare parts recommendation and price list.
• Information to be Submitted for Owner Approval After Receipt of Order

(*) The drawings and data detailed in paragraph 7.1 shall show the equipment as ordered. Typical drawings are not acceptable unless revised to show as built equipment and identify the specific equipment ordered. The number of copies required will be indicated on the Data Sheet.

• Certified Information to be Supplied
• Certified drawings and data requested in paragraph 7.2 and 7.3 shall be supplied.
• Certified test reports for all tests required in paragraph 6.1 and/or 6.2 as specified.
• (*) Installation Operation and Maintenance manuals shall be provided in the method and quantity indicated by the agreement purchase order.

8.0 (RESERVED)

SHIPPING

• Motor shafts shall be shipped with a protective covering when shipped without a coupling. The key shall be shipped with the motor and shall be prominently tagged for easy identification.
• (*) Other shipping instructions and destinations will be covered in the Data Sheet and/or Purchase Order.

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