Section 13 — Electrical

Induction Motors NEMA Frame 500 HP and Below Explosion Proof

IPE Engineering Practice IPE-EP-13-3-4

Document number: IPE-EP-13-3-4 · Section: 13 — Electrical

1.0 SCOPE

1.1

1.2

1.3

1.4

This Practice covers requirements for AC fractional and integral HP, T frame, polyphase induction motors below 600 volts,500 HP and Below explosion proof. Included as part of this Practice is a Data Sheet (EP 13-3-4DS) listing specific equipment requirements. In cases of conflict between the Data Sheet and the Practice, the Data Sheet takes precedence.

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

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

DEFINITIONS

• Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
• Explosion Proof Motors - Motors for use in Class I or II, Division I classified locations as defined by the National Electrical Code shall comply with UL 674 and bear the UL listing mark.
• 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
• Balance and Vibration
• Motor rotors shall be dynamically balanced. The use of solder or similar deposits for balancing is not acceptable. The use of balance washers is acceptable. 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 vibration levels below when tested at no load per NEMA MG 1.
• 0.5 to 2 HP motors; 2 pole - 0.001 in Pk to Pk, 4 Pole 0.015 in Pk to Pk, and 6 pole

0.002 in Pk to Pk maximum.

• 0.5 to 200 HP explosion proof motors; velocity - 0.15 in/sec Pk, amplitude 0.015 in Pk to Pk maximum.
• 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 fill locations shall be provided with ZIRK fittings.
• As a minimum, 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.
• Breathers and Drains

Explosion Proof Motors shall be supplied with combination stainless steel breather and drains or separate breather and drains. The drain and breather shall be U.L. Listed.

• 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 of explosion proof motors including all air flow passages shall be coated with a rust inhibiting primer and finished with an epoxy paint.
• Conduit Boxes
• Cast iron conduit boxes shall be sized per NEMA MG-1 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 as a minimum shall be supplied with a ground connection as detailed in paragraph "2" below:
• If Manufacturer's standard requires, the motor frame shall be provided with a tapped hole (1/4 or 3/8 inch National coarse thread bolt) to accommodate a compression lug for the Owner's #2 AWG copper ground wire. The hole shall be drilled and tapped into a foot or base of the motor, in such a manner as not to weaken the structure. Under no circumstances shall the hole be drilled directly into the housing of the motor.
• A grounding connection lug shall be provided on all motors within the motor terminal box. The lug shall be suitable for the ground wire size specified on the data sheet.
• 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.
• Enclosures
• TEFC (severe duty) enclosures shall be of all cast iron construction including conduit boxes, frame, end brackets, fan covers and mountings.
• Explosion Proof motors shall be suitable for Class I, Division I, Group D locations (or group as otherwise specified on the Data Sheet) and shall have corrosion resistant cast iron enclosures, including stator frame, end brackets, fan cover, conduit boxes, and mounting feet.

• A non-sparking, non-corrosive water seal/slinger ring shall be installed on the drive end of the motor shaft to protect against entrance into the bearing of moisture or dust.
• 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.
• Hardware: All hardware, including frame bolts, conduit box bolts, name plate fasteners, grease caps or plugs, fan clamp and bolt, drain plugs or fittings, and etc., shall be of corrosion resistant stainless steel or zinc plated steel.
• 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.

• Motor windings shall be furnished with class F insulation and not exceed Class B temperature rise by the resistance method (based on a maximum ambient temperature of 40°C) while operating at rated load (1.0 SF) and shall not exceed 90°C (Class B factor temperature rise) by the resistance method at service factor load. The motor shall be rated for continuous operation at full service factor load and 40°C ambient.
• The stator winding insulation system shall be applied using multiple dips and bakes with a non-hygroscopic, inorganic varnish (NEMA MG1-1.27.1). Motors 30 HP and less may be supplied with a sealed insulation system (Reliance Electric Company proprietary epoxy sealed system) (NEMA MG1-1.27).
• 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 as a minimum.
• Nameplates
• Nameplates shall be easy to read and made of stainless steel. Nameplates for explosion proof motors shall include "T" (temperature identification) numbers as specified in the National Electrical Code (Article 500-5(d)).
• The front and rear (or guide and thrust) bearing numbers shall be stamped on the name plate and be in AFBMA nomenclature.
• Unidirectional motors shall have a rotation arrow plate on the motor frame.
• Explosion proof motors shall have the UL Label attached to the motor frame or shown on the nameplate. If separate from the nameplate, it shall be mounted adjacent to the nameplate.
• Noise Levels
• Unless specified otherwise, the maximum (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

3) The Manufacturer shall quote a standard motor with a 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 the 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 in Section 21 on the Data Sheet, space heaters shall be arranged to provide the optimum attainable uniform heating of the stator windings.
• Surface temperature of the heater elements or the motor enclosure shall be suitable for the classified area specified on the Data Sheet, and shall not exceed 80% of the ignition temperatures as specified in NFPA 70 Para.501-3(b)2.
• 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 MG1-12.50 at rated 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. 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.

Special Applications

Vertical Motors

• The General Requirements of paragraph 5.1 of this Practice 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 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.
• Shaft voltages/current due to harmonics which may cause bearing failure.

TESTING

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

• Routine/Commercial Test

Each motor shall be given a routine (commercial) test to demonstrate that it is free from mechanical and electrical defects. This test shall be conducted in accordance with the latest edition of ANSI/IEEE Std 112. Certified test copies shall only be provided when specified by the data sheet. As a minimum this test shall include:

• Measurement of no-load current (each phase).
• Measurement of no-load speed.
• 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 of this Practice. 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.

• 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 normal 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.
• Max allowable locked rotor time with winding temperature at rated ambient and with winding temperature at rated rise.
• Temperature identification number ("T" Rating, NEC Article 500) for explosion proof motors.
• Noise Level (dbA) measurement at 3 feet.
• The information specified in 7.1.3 of this Practice 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.
• Alternate proposals are acceptable provided a primary proposal that meets this Practice is submitted.
• Complete descriptive information on the motor quoted shall be supplied. Features supplied but not necessarily specified shall be identified.
• Information to be Submitted for Owner Approval After Receipt of Order

The drawings and data detailed in paragraph 7.1 of this Practice 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 of this Practice shall be supplied.
• Certified test reports for all tests required in paragraph 6.1 and/or 6.2 of this Practice as specified.
• Installation Operation and Maintenance manuals shall be provided in the quantity shown on the Data Sheet.

8.0 SPARE PARTS

A complete spare parts recommendation based on the total purchase order is required within 30 days after the vendor receives the purchase order. Spare parts recommendations shall include a list of priced spare parts as recommended by the vendor to be on hand during start up and the first year's operation.

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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