Attachment 1 - SOW Refurbish Fan Motors.pdf

SOW NO. 11524-25-001

14 Jan 2025

STATEMENT OF WORK

FOR

SERVICE TO REFURBISH FAN MOTORS

NATIONAL FULL-SCALE AERODYNAMICS COMPLEX

MOFFETT FIELD, CALIFORNIA 94035

DISTRIBUTION STATEMENT A. Approved for public release: distribution is unlimited.

Table of Contents

1 SCOPE

1.1 Summary

1.2 Background

2 APPLICABLE DOCUMENTS

2.1 Government Documents

2.2 Non-Government Documents:

3 REQUIREMENTS

3.1 Schedule

3.2 Security Requirements

3.3 Safety Plan

3.4 Safety Orientation

3.5 Confined Space, Lock-Out/Tag-Out (LOTO), and Nacelles

3.6 Job Safety Analysis

3.7 Fire Requirements

3.8 Hazardous Materials

3.9 Products

3.10 Protection of Property

3.11 Cleanliness

3.12 Stator Shift

3.13 Stator/Rotor Cleaning and Maintenance

3.14 Inspections

3.15 Painting

3.16 Stator Shift Back

3.17 Testing

3.18 Verification, and Acceptance

3.19 Submittals

1 SCOPE

1.1 Summary

This specification defines the requirements for the work associated with the inspection, testing, cleaning, and as needed repairs of fan motor(s) within the National Full-Scale Aerodynamics Complex (NFAC) wind tunnel fan motor drive system. Removal of the fan motor from the nacelle is not an option. All work shall be performed on site. Work shall be performed at NASA Ames Research Center located in Moffett Field, California.

1.2 Background

1.2.1 Brief Fan Motor Drive Description

The Fan Motor (FM) drive system consists of 6 FMs connected to 40 ft diameter fans, which push air through the wind tunnel. The FMs are each encased in a 26 ft diameter nacelle. There are two levels with three nacelles on each level. Access to the motor is through openings in the bottom of the nacelle on each end of the motor. An additional 60 in x 26.5 in access hatch on the slip ring end of the motor is available for hoisting material and equipment into the nacelle. The openings are approximately 13 ft above the floor. A freight elevator is available to carry personnel, tools, and materials to each of the floor levels.

Each of the six fans in the NFAC wind tunnel is driven by an 18,000 horsepower, 180 RPM, pedestal type synchronous motor. To support the motor and fan, a complete fan drive shaft bearing system is composed of three parts two drive motor bearings and one combination thrust and journal fan shaft bearing. The two drive motor bearings are 22 in diameter, tilting pad journal bearings that support the motor rotor and couples the motor rotor to the fan shaft. The combination thrust and journal fan shaft bearing supports the fan end and consists of a 22 in diameter, tilting pad journal bearing and a 30 in, 16 x 16 tilting pad main thrust bearing. Each bearing is supplied with its own independent, high pressure, hydrostatic lift oil system. A common reservoir and pump system supplies lube oil to all 18 bearings.

There are 40 field poles on each motor. There are 126 turns on a field pole. All the 1-1/4 in field pole retaining bolts (4 per pole, 160 per motor) were replaced in 1999 due to poor design of the rotor. The poor design allowed cyclic loading on the bolts, alternating every revolution which led to bolt failures. The cyclic loads were also transmitted to the amortisseur bars, through the shorting rings, to the adjacent poles. The cyclic loading on the amortisseur bars caused their eventual fatigue failure on 18 poles.

1.2.2 Fan Motor Nameplate Data

Manufacturer Style

WESTINGHOUSE SYNCHRONOUS MOTOR

Type and Frame HP. % Load HR.

HP-40-167 18000 100 24

Hertz Volts RPM. OC Temp. Rise

60 6600 180 80

Ph. Amp. Exc. Volts Instr. Book

3 1212 250 1070DA

Service Factor %PF Exc. Amp Insulation Class

1.25 FOR 2 HRS,

110 OC RISE

100 465 F

1.2.3 Fan Motor Condition

As of January 2025, the 6 fan motors have seen about 6295 hours of operation (each motor) and 4360 starts (each motor). Their maximum operating temperature is assumed to be 96O C as a representative reoccurring maximum, even though they peak at different maximum temperatures over their life: FM1 at 108.3O C, FM2 at 115.8O C, FM3 at 113.7O C, FM4 at 101.5O C, FM5 at 103.5O C, and FM6 at 109.6O C.

The fan motors were last thoroughly cleaned and inspected in December 2010.

During this clean and inspection, dusty contaminants were found in the slots as well as in the end-regions of the stator winding. Contaminants were cleaned using solvent and rags. The work in this specification is the same scope previously performed in 2010. Stators were shifted, cleaned, and then recoated.

Test data from this effort is available upon request.

More recently, in February 2024, thorough testing and inspections were performed by ABB. From the reports (which are available upon request), it was determined that all the motors need maintenance, including the need for cleaning with special attention at the slot exit and end winding areas. These areas need to be cleaned and thoroughly inspected, which would be best accomplished with the stator shifted. ABB tests revealed evidence of slot end and surface discharge activity, high charge storage values, and low volume resistivity, among other findings.

yielded a rating for the insulation due to contamination of the windings and/or void formations as a result of thermal cycling. This puts the motors past mid-life on their designed life-curve. Thermal cycling has been found to be the dominant driver behind the aging of the fan motors. However, performing the recommended maintenance to remove the contamination could improve the insulation condition condition, indicating it is acceptable for longer term continuous operation with regime.

Contamination and Moisture

The charge storage as determined from the Polarization-Depolarization Current Analysis (PDCA) was found to be higher than what is normally observed in windings without contamination and could be mainly attributed to the presence of moisture along with contribution from minor contaminants. Also, the nature of the charging curve (PDCA graphs) is indicative of the flow of currents being controlled by electrochemical charge storage effects, or by presence of homopolar charges. Homopolar charges can be created by the presence of moisture in the contaminant or due to excessive humidity, or even from rust deposits due to moisture. The presence of moisture is the most likely explanation given the high humidity average of the Bay-Area climate in winter, which was the time of the measurements.

The volume resistivity is below what is normally observed for the class of insulation used. This is most likely due to the presence of homopolar charges and possibly the presence of moisture in the leads/termination areas of the winding, which could lead to increased leakage currents during charging measurements. This finding confirms the observed presence of moisture in combination with contaminants, especially in the end regions. Cleaning is expected to restore this value.

Thermal Cycling

The exact composition is not known of the end windings, but some part of it might have worn off at the surface of the insulation as a result of movements induced by thermal cycling.

There is some evidence of a lack of electrical contact between the outer layer of the windings (corona protection shield) in the slot area and the slot. This is attributed to either the presence of impregnating resin in localized areas between the corona protection shield and the slot, the accumulation of charges near the electrodes (i.e. in the air spaces between coil and slot), or the looseness or degradation of the slot corona protection. This area is expected to be affected the most by thermal cycling stress that is typical for this application.

The partial discharge patterns indicate dominant gap discharge at the lower voltage level, both at line-end, as well as at neutral-end. Both Discharge Inception Voltage (DIV) as well as Discharging Void Volume Content (DVVC) are compared. DVVC is an indicator of the insulation health, reflecting the volume of discharging voids in the insulation. The DVVC can be evaluated from the variation of the capacitance and tan delta above discharge inception.

Acceptable values of DVVC are less than 0.5% for class F & H insulation and less than 1.0% for class B insulation. At neutral end, more than at line end, there is evidence of dominant gap discharges to ground at lower test voltages, along with contributions from slot end and surface discharge at the higher test voltages, which could have led to erosion/damage to the coils located near the neutral end. This is most likely an effect that comes hand in hand with higher thermal stress (mostly cyclic) on the neutral end, since cooling air is passing from line to neutral end. There is also evidence of the discharging of voids and delamination within the insulation from the partial discharge patterns recorded, which completes the picture of high cyclic thermal stress and/or some presence of vibration.

The dispersion ratio is greater than what is normally observed in this class of insulation system. The dispersion rate for the insulation of motors refers to the rate at which electrical charges disperse across the insulation material. It's an important parameter that affects the performance and longevity of motor insulation

Need for Cleaning

The winding cleaning will help reduce the extension of the earth potential beyond the stator core area and thus reduce electrical stresses. By reducing the extension of the earth potential, the electrical field distribution becomes more uniform, reducing the likelihood of high stress points that could cause surface partial discharge and eventually insulation breakdown.

The contamination at the end of the slot is in a critical location, when considering winding designs. The winding contains a stress grading system at the end of the slot. In addition, the stator coils are attached to the stator core via a support ring on the end windings. This causes twisting stresses in the slot exit region of the stator windings. If the insulation becomes weak, a surface crack or fissure could develop, and if there is contaminant ingress, a localized area of weak insulation develops. The risk is when this weakness is located near the line side of the winding. This observation applies to FM5 and requires special attention during inspection and cleaning.

2 APPLICABLE DOCUMENTS

2.1 Government Documents

2.1.1 AEDC SHE Standards

A. A6 User and Contractor Safety.

B. A10 Job Safety Analysis.

C. B1 Master Work Permit.

D. B2 Lockout/Tagout.

E. B3 Control of Hazardous Area Using Safety Signs, Tags and Barricades.

F. B5 Confined Spaces.

G. D5 Hoisting Devices.

H. D8 Portable Power Tools.

I. D9 Fixed and Portable Ladders.

J. E17 Oil and Hazardous Substances Spill Response.

K. E18 Managing Wastes Containing Chemical or Petroleum Products.

L. F2 Personal Protection Equipment (PPE).

M. F5 Hazardous Noise and Hearing Conservation.

N. F6 Fall Protection.

2.1.2 NFAC Study Reports

A. ABB Life Expectancy Analysis Report of Stator Winding Insulation

B. TECO Westinghouse Evaluation for VFD Operation

2.1.3 Drawings

A. A421-7830-MS103 SH. 1 WESTINGHOUSE TYPE HR

SYNCHRONOUS MOTOR

OUTLINE

B. A421-7830-MS103 SH. 2 WESTINGHOUSE TYPE HR

SYNCHRONOUS MOTOR

OUTLINE

C. A321-8140-MS5 WAUKESHA BEARINGS CORP.

FAN BEARINGS COMBINATION

16x16 PAD THRUST BEARING

D. A321-8140-MS3 WAUKESHA BEARINGS CORP.

JOURNAL & AXIAL LIMITATION

THRUST BEARING

E. A321-8131-M112 MOTOR STATOR AND

BEARING MOUNTING DETAIL

F. A321-8131-M935 ACCESS HATCH, STATOR

HOLD DOWN BOLTS

G. A321-1230-M100 SHT. 1 OF 5 SPACE HEATER RACK

ASSEMBLY

2.2 Non-Government Documents:

2.2.1 Standards

A. OSHA CFR General Industry Safety and Health Standards

B. ANSI/IEEE 43-2000 Recommended Practice for Testing Insulation Resistance of Rotating Machinery

C. ANSI/IEEE 115-2009 Test Procedures for Synchronous Machines Part 1 Acceptance and Performance Testing; Part 2- Test Procedures and Parameter Determination for Dynamic Analysis

D. ANSI/ IEEE 118-1977 IEEE Standard Test Code for Resistance Measurement

E. ANSI/NEMA MG-1 Motors and Generators

F. ANSI/NETA MTS Maintenance Testing Specifications

3 REQUIREMENTS

3.1 Schedule

3.1.1 The tasks covered in this Statement of Work are not necessarily listed sequentially. It is the Contractor will be performed in a logical manner. Contractor shall provide a schedule of events one week prior to start of onsite work. Schedule shall be updated weekly to reflect ongoing events and provided to the Government after each update.

3.1.2 This work effort will have to be performed so as not to conflict with ongoing wind tunnel activities. The Government shall provide the Contractor with the allowable schedule window(s) to perform on-site work.

3.1.3 A detailed schedule of activities with estimated dates and durations will be provided to the Government for review and approval.

3.2 Security Requirements

3.2.1 Personnel coming on site shall go through a security check prior to arrival.

Personnel shall pass security check to be allowed on site. A visitor pass and/or local badge will be issued after satisfying all security requirements. The visitor pass or local badge shall be always adorned while on site.

3.2.2 List of personnel shall be provided ahead of first visit. List shall be provided at least 3 weeks prior to first visit.

3.2.3 Each listed personnel requesting site access shall watch for emails from NASA throughout the badging process, answer each email, and carry out all instructions.

3.2.4 US Nationals and Green Card holders shall be permitted. No Foreign Nationals will be allowed on site.

3.2.5 US Citizens must

and/or unexpired passport for a National Crime Information Center (NCIC) security check. The required IDs depend upon the type of citizenship and/or type(s) of pass/badge. All documents presented must be originals and the names must match exactly. Digital copies stored on phones are not acceptable.

Green Card holders require additional forms of ID.

3.2.6 All badges and passes must be returned by the last day of the visit or when no longer needed.

3.3 Safety Plan

The Contractor shall provide a Safety Plan based on the relevant SHE Standards prior to any onsite work. The Safety Plan shall be provided 2 weeks prior to site visit for review for approval by the Government. The Safety Plan shall highlight asbestos and lead awareness, and confined space and lock-out-tag-out training.

The Safety Plan shall include a high level of tasks to be performed on site.

Each task shall list hazards associated with the effort. Mitigation techniques shall be listed for each hazard listed.

3.4 Safety Orientation

All Contractor personnel performing on this project are required to attend a safety orientation with the Government Safety Officer prior to participating on any onsite work activities. Orientation will be no longer than 1 hour. Contractor shall notify the Government of any change of personnel as soon as possible so the Government Safety Officer can be scheduled for a safety orientation.

3.5 Confined Space, Lock-Out/Tag-Out (LOTO), and Nacelles

All Contractor personnel shall observe and understand the policies set forth by the Government. These policies include confined space procedures and requirements as well as adherence to the LOTO process prescribed by the Government.

3.5.1 Confined Space

All Contractor employees who plan to enter the nacelles shall have certified confined space training and shall undergo a safety orientation by the Government Safety Officer. Certificates of completed training within 1 year shall be provided to the Government with the Safety Plan.

3.5.2 LOTO

No person shall enter a nacelle without the necessary LOTO applied and accompanied by an observer with confined space training. Contractor personnel entering the nacelles shall be trained to work in confined space and

LOTO.

3.5.3 Nacelles

Nacelles have limited accessibility and require access via a permanently height and there are a couple uneven steps on the way up into the nacelle. It is not anticipated that scaffolding will be required. If the Contractor opts to use scaffolding, coordinate with the Government for approval and provide safety requirements in accordance with the relevant SHE Standard. The elevator used to access the two fan drive levels where the fan motors are housed is a standard passenger elevator design with a capacity of 4,500 pounds. It has an entrance opening of 4 ft wide x 7 ft high, and interior dimensions of 5 ft 9 ½-in wide x 7 ft 6 in deep.

3.6 Job Safety Analysis

While on site performing work, the Contractor shall perform a Job Safety Analysis (JSA) daily based on the relevant SHE Standard. If activities of the day are the same as the previous day, the previous JSA shall be reviewed each morning and updated with minor changes as necessary. The Government may request to review JSA at any time while work is being performed on site.

3.7 Fire Requirements

Welding is not permitted by the Contractor. If required, the Government will coordinate with the Contractor to have a certified site welder assist. The Government will coordinate all required permits.

Precautions shall be taken on any heating devices used to help reduce moisture in the motors. Anti-tip safety or overtemperature protective features shall be fully functional, if equipped.

3.8 Hazardous Materials

All used and contaminated rags shall be gathered and placed in either a bag or container. Bags and/or containers shall be properly labeled.

Walls onsite may be constructed with asbestos and/or painted with lead paint.

Insulating material used on piping may contain asbestos. Be aware of surrounding infrastructure and avoid contact if possible. Proper hygiene such as washing hands before ingesting food should be always observed.

3.9 Products

3.9.1 General

The Contractor shall furnish all services, tools, materials, and labor necessary to complete the work described in this specification. All materials, solvents, insulating varnish used by the Contractor shall be compatible with existing equipment and materials.

3.9.2 Government will furnish the following:

A. Brushes as needed per motor.

B. One set of jacking screws for shifting motor stator.

C. Sets of 10 rollers to shift stators (five each per side).

D. Illumination in all nacelles.

E. 100 psi shop air will be available upon request.

F. Two (2) 15 Amp, 120 Volt duplex receptacles, and one (1) 30 Amp, 120/208 Volt 3 phase receptacle in each nacelle.

G. Brush holders and springs as needed per motor.

H. Set of 10 stator hold down bolts and associated nuts and washers.

Note: Existing bolt threads were damaged intentionally to prevent the nut from fully backing out if it were to come loose.

I. Set of 160 field pole retention bolts and associated washers and locking plates.

3.9.3 Polyurethane Varnish

A. Only polyurethane varnish which is environmentally safe will be permitted.

B. Insulating varnish shall be red in color, rated Class F, tough, flexible and fast drying (30 minute cure time at 25O C).

C. Insulating varnish shall be abrasion, chemical, and moisture resistant.

D. Insulating varnish shall be -41 air drying polyurethane varnish or approved equal.

E. Product specification shall be submitted to the Government for review and approval.

3.9.4 Insulating Sleeves

A. Insulating sleeves shall be Tyco medium-wall tubing type BPTM (5-25 kV).

B. 6 sleeves are required per motor.

C. Contractor shall determine length.

3.9.5 Cleaning Solvents

A. Safety Data Sheets (SDS) shall be made available upon request.

B. Cleaning solutions shall not be conductive and/or leave a residue.

C. Solvent shall be electrically safe and not damage the existing insulation coating.

D. The Contractor shall submit list of solvents to the Government for review and approval.

3.9.6 Rigging Equipment

A. All equipment shall be certified.

B. The Contractor shall inspect all rigging prior to use. The Contractor shall verify lifting equipment is operating per manufacturer specifications.

C. All frayed, damaged, non-working items should be set aside and labeled as damaged to prevent accidental use.

3.10 Protection of Property

During performance of work, the care and protection of existing work, NASA- AMES equipment, and adjacent areas shall be the responsibility of the Contractor, and any damage thereto shall be repaired at the sole expense of the Contractor.

Specific attention shall be directed to ensure that the slip rings, shaft journals, bearings, and motor winding insulation are physically protected from impact abrasion, debris, or other damage during work.

3.11 Cleanliness

The Contractor shall always maintain a clean work area. Particular attention shall be paid to removal of used solvents, storage of oily rags, cleanup of slippery or oily areas, hazardous temporary placement or storage of equipment, and other actions necessary to ensure the safety of both personnel and equipment.

The Contractor shall clean up the work area of all debris and tools upon the completion of the work each day.

3.12 Stator Shift

3.12.1 Removal of Connections

A. 7.2 kV connections stemming from the surge packs shall be disconnected before the stator is shifted. The surge packs connect to the motor via 2 500 MCM cables per terminal. There are 6 terminals.

Currently, the leads are bolted to the terminals with Raychem shrink tubing encasing the connection. There are no stress cones.

B. There are 6 sets of RTD leads, 720 tooth gear tachometer pickups, RTD space heater power leads which shall be disconnected.

C. Disconnect and tape RTD wires, identify wires for reconnection and remove RTD j-box. (RTD j-box is located on the slip ring side of fan motor in the respective Nacelle).

D. Remove bolts from the RTD j-box 90° mounting pedestal to allow movement around Nacelle rib.

E. Disconnect wiring and conduit from space heaters and identify wire and conduit for reconnection.

F. Carefully mark tachometer gear tooth sensor support bracket location, remove bolts, and fold sensors out of the way. Prior to loosening the gear tooth sensor, use a feeler gauge to measure the air gap between the sensor and tach gear ring. Record gear tooth sensor air gap measurements on inspection sheets.

G. Disconnect 1-250 MCM ground cable at the ground pad. (Ground is located on slip ring side of fan motor, east side).

3.12.2 Remove End Bells

A. The Contractor shall remove access panels with their certified lifting equipment, if required.

B. The stator end bell positions shall be recorded and the end bells removed on both sides of the motor. There are 6 end bell segments on the coupling side, each weighing 226 lbs. There are 10 end bell segments on the slip ring side, each weighing 306 lbs. The Contractor shall provide their own hoist for removing the end bells.

C. One hard point is available for rigging on each side of the motor. The Contractor shall inspect hard points and determine that they are adequate for the intended load.

3.12.3 Outer Nacelle Scaffolding

A. Contractor shall install scaffolding on the outside legs for access hatch panel removal to expose the stator bolts.

A. Access hatch panel utilizes machines screws and dowels for attachment to nacelle. See drawings.

B. Scaffolding shall be clean. Excess dirt, concrete, paint, etc. shall not be used for all installations on site.

C. Contractor must be a certified scaffolding installer and must be present to certify the scaffolding installation to the Government Safety Officer.

D. All scaffolding will be inspected by the Government Safety Officer after installation.

E. Contractor shall perform daily inspections and log scaffold inspections.

3.12.4 Shift Out of Position

A.

a suggested procedure below. This procedure has been used in the past. Procedure for shifting the stator is the responsibility of the Contractor and the procedure shall be subject to review by Government prior to initiating changes and beginning work. The setup and alignment measures are critical to fan drive operation and the utmost care and attention to detail shall be taken.

B. Suggested Plan

A. Set up scaffolding on outside legs for access to hatch panel removal.

B. Blue surfaces, scribe, and punch mark exact stator location.

C. Measure air gap and record data.

D. Remove outside access hatch panel to expose stator bolts. Refer to drawing A321-8131-M935 for details.

E. Remove any obstacles within the stator path (conduits, HAD , RTD junction boxes, and tachometer mounting hardware after disconnecting space heaters, HAD ).

F. File and clean the threads on both ends of each stator bolt to allow nut to pass.

G. Install jacking screws (4 each stator).

H. Remove dowel pins (2 ea.) downstream side of stator.

I. Remove stator studs using stud tensioner to break nuts loose (10 each stator). Set stud tensioner to 12,500 14,500 psi.

J. Jack up stator using jacking screws (distance of a few thousandths of an inch).

K. Remove shim packs. Identify and mark location on each shim pack.

L. Clean roller tracks of oil, grime, or any other substance.

M. Install rollers (5 each per stator side).

N. Lower stator onto rollers using jacking bolts.

O. Rig to pull stator aft (rigging rated @ 4000 lbs).

P. Station observers (3 total) and two riggers to operate pull jacks.

Q. Secure stator against movement while on rollers.

C. Deviations to this plan shall be submitted for review to the Government.

3.12.5 Inner Nacelle Scaffolding

A. The Contractor shall install scaffolding on the slip ring sides of the motors to provide access for cleaning the windings.

B. The Contractor may install scaffolding on the coupling sides of the motors.

C. If desired, some scaffolding may be installed before removing the end bells, especially on the slip ring side since there is no floor next to the motor.

D. Scaffolding shall be clean. Excess dirt, concrete, paint, etc. shall not be used for all installations on site.

E. The Contractor must be a certified scaffolding installer and must be present to certify the scaffolding installation to the Government Safety Officer.

F. All scaffolding will be inspected by the Government Safety Officer after installation.

G. The Contractor shall perform daily inspections and log scaffold inspections.

3.13 Stator/Rotor Cleaning and Maintenance

3.13.1 Cleaning Plan

A. The Contractor shall prepare a detailed plan for cleaning the Fan Drive Motors for Governments review and approval.

B. It is important to recognize this work will be done in a confined space and all appropriate precautions shall be taken. Breathable air shall be forced through the nacelle throughout the cleaning process. The Contractor shall provide all necessary blowers to achieve this.

3.13.2 Initial Clean Around the Motor

A. This initial vacuum cleaning shall be performed on both sides of the motors. Where possible, use a soft non-metallic brush on exposed surfaces to loosen the dirt. Compressed air can also be used to loosen dirt. Compressed air at no more than 30 psig may be used to blow debris from areas not accessible with the vacuum.

B. Scaffolding itself and the installation of it may have some dirt and debris.

Clean and remove to prevent it from getting into the motor.

C. Wipe with solvent and rags around the area to prevent distribution of dirt into the motor. This cleaning shall be performed on both sides of the motor, as required.

3.13.3 Cleaning Motor Using Rags and Solvent

A. The stator windings and field windings shall be cleaned. A vacuum shall be used to collect dry dirt and other materials engaged with any exposed areas of the windings. An organic, non-toxic, and non-flammable solvent shall be used to clean buildup of grease and dirt from the stator windings and field poles.

B. Insulation resistance measurements shall be taken before cleaning, after major steps in cleaning, and after completion of the work.

C. Cleaning with an approved solvent can be done where appropriate. This should be done using rags that are moistened but not dripping with an organic, non-toxic, and non-flammable solvent or equivalent as approved by Government. Care shall be taken to avoid solvent running and carrying dirt or other contaminants into cracks or crevices where it could have a deleterious effect on the insulation resistance. Use shall be in accordance with Government safety rules concerning the use and disposal of solvents. Disposal of solvent soaked rags and solvent will be the responsibility of the Contractor.

D. In cases where a low power solvent will not provide proper cleaning and a stronger solvent becomes necessary, a solvent recommended by the Contractor may be used when approved by Government in accordance with applicable safety regulations.

E. When a stronger solvent is used definite precautions shall be taken to prevent breathing air containing excessive concentrations of its vapor.

Satisfactory ventilation of the area shall always be provided. If this is not practical, adequate respiratory protection shall be used. Such protective equipment may consist of chemical cartridge respirators or suitable gas masks. If there is any possibility of oxygen deficiency, breathing apparatus with a self-contained air supply, air line respirators, or hose masks shall be used. All protective breathing equipment shall have the U.S. Bureau of Mines Approval.

3.13.4 Cleaning Motor Using Dry Ice

A. The stator shall be cleaned as much as possible with the dry ice cleaning method. Dry ice shall be used to remove the contaminants that are mostly solid or paste-like.

B. Utilize heat to remove any moisture that could have formed on the surface during the cleaning process or formed from the compressed air (if it is not sufficiently dry).

C. Oily contaminates might require the use of a cloth dampened with solvent to wipe off. If this process is utilized, heat the end-windings to get rid of residual solvent. Heating should be done with hot air blowers.

See Cleaning Motor (Rags and Solvents).

3.13.5 Cleaning Motor Using Low/Mid Pressure Water and/or Hot Steam

A. The stator and rotor shall be cleaned with low to mid pressure water.

B. Sensitive electrical equipment and bearings in the area shall be shielded from possible water ingress.

C. Containment shall be created to capture all water runoff. Captured water shall be disposed of properly.

D. Make-shift oven or encasement of the motor with heaters shall be installed to bake the water out of the motor.

3.14 Inspections

3.14.1 General

A. Inspect stator coils for deterioration or degradation of insulation, such as general puffiness, flaking, brittleness or drying out, swelling into ventilation ducts, or lack of firmness of the insulation, resulting from aging. Check for cracks especially at the end of the slots.

B. Inspect stator coil wedges and filler strips for migration and tightness in the slots.

C. Check the parallel ring supporting structure for tightness of coil bracing and inspection of blocking or felt between end turns.

D. Look for damage from corona or slot discharge. Report any such conditions as concerns on the relevant inspection sheets and map locations of deficiencies.

E. Check field coil washers and cells for cracks and broken edges. Check connections between field coils and to the collector rings for loose joints, overheating, deteriorated insulation, or loose mechanical supports.

Check pole attachments to the spider for tightness. Make sure that field coils are not loose on the poles such as field coils can move outward and inwardly with changes in rotational speed. Report any such conditions as concerns. Record on relevant inspection sheet.

3.14.2 Wedges

A. The wedges shall be inspected for tightness and migration. If there is evidence of migration, it shall be recorded on relevant inspection sheet.

B. If necessary, tap migrated wedges back in place and use an epoxy

3.14.3 Amortisseur Winding

A. All amortisseur windings, both bars and shorting rings, shall be inspected for evidence of arcing and broken welds.

B. Check tightness of bolted connections.

3.14.4 Other Windings and Electrical Connections

A. All other windings and electrical connections shall be inspected for loose or broken connections, evidence of arcing, or any other problem. If a problem is encountered, the Contractor shall immediately notify the Government.

3.14.5 Space Heaters

A. The space heaters are located underneath the motor. They will not be accessible when the stators are shifted. Check and measure resistance and continuity of each space heater phase. Record on relevant inspection sheet.

B. There are a total of 12 space heaters per motor, 4 in parallel per phase.

The heaters are rated 750 W, 120 V, 6.25 A calculated, with a total output of 9000 W for each motor. Contractor shall verify operation of heaters and measure and record heater phase currents for each motor.

3.14.6 Slip Rings

A. Measure runout. Install a dial indicator on each collector ring. The Government will manually turn the fan motor shaft for the Contractor by pushing on the fan blades. Check and record on inspection sheets the total indicated runout and if it is greater than 0.005 inch. If run out exceeds 0.005 inch, the Government shall be notified immediately for review, otherwise the inspection shall be noted.

B. Inspect condition of the rings. Check for brush imprints, non-uniform or excessive wear, non-uniform color or rough surfaces on the collector rings. Check that the rings are tight (no evidence of movement) on the shaft. Check finish of hub insulation for smoothness and cleanliness.

3.14.7 Brush Holders

A. Check that the brushes are free to move in each box throughout complete travel of the spring. Repair or replace boxes where fingers stick or brushes stick in the brush holders.

B. Check for worn fingertips and wear at the shaft and fingers. If a problem exists, repair or replace. The Government will supply replacement brush holders and springs.

C. Inspect both slip ring brush holders and the shaft grounding brush holder.

3.14.8 Brushes

A. Check and adjust brush holder to achieve 3/32 to 1/8 inch clearance between each brush holder and the collector ring. Check and replace brushes that are less than 1 inch long or brushes that are damaged.

Damage includes chipped, cracked, grooved, double faced, overheated brushes and broken shunts.

B. Check and sand brush faces to obtain at least 80% contact against the collector rings if new brushes are installed.

C. Check and set brush spring tension to 2.3 to 2.5 lbs.

D. Record all the above checks on the relevant inspection sheet.

3.14.9 Bearing Pedestal Insulation

A.

Government.

B. This includes the insulation of all components connected to a pedestal as well as the sheet of insulation under the pedestal and the insulating tubes and washers on the mounting bolts and dowels in so far as accessible.

3.15 Painting

3.15.1 Spray painting materials/products and method of application shall be prepared in a plan by the Contractor and provided to the Government for approval.

A. Plan shall include ventilation methods.

B. Follow manufacturer specifications for proper application and curing.

3.15.2 A spray insulating varnish, approved by the Government, shall be used for painting.

3.15.3 The field pole mounting bolts, amortisseur shorting ring, and electrical connections shall be painted with insulating varnish. The stator windings and field poles shall be painted with insulating varnish.

3.15.4 If necessary, heat shall be applied for proper curing.

3.16 Stator Shift Back

3.16.1 Hook up rigging to pull stator on upstream side of stator (in mid nacelle, plate clamps).

3.16.2 Pull stator into position slowly and safely. Keep in constant communication as a team while moving the motor.

3.16.3 Align stator so dowel pins can be installed.

3.16.4 Check all alignment measurements.

3.16.5 Jack up stator with jacking bolts, just enough to remove rollers.

3.16.6 Gather new stator hold down bolts and associated nuts and washers. Install stator hold down bolts. (DO NOT TIGHTEN).

3.16.7 Install shims into original positions.

3.16.8 Lower stator with jacking bolts.

3.16.9 Check all measurements to include air gap by a qualified person (Millwright or Machinist).

3.16.10 Run top nuts down on threaded studs two inches.

3.16.11 Run bottom nuts up on threaded studs until hand tight.

3.16.12 Install stud tensioner on an end stud (use crisscross pattern working from ends to middle) with a calibrated and certified gauge and pump up to 13,925 psi (+/- 175 psi).

3.16.13 Tighten nut by hand using the handle on the tensioner.

3.16.14 Release pressure to zero psi.

3.16.15 Repeat steps #10-14 on remaining studs using a crisscross pattern working from ends to middle.

3.16.16 Repeat entire crisscross torquing procedure twice more on each of the 10 threaded studs.

3.16.17 Check all measurements to include air gap by a qualified person (Millwright or Machinist).

3.16.18 Perform preventative loosening measures such as intentionally damaging thread on the stator bolts for the top and bottom nuts to prevent the nuts from backing out.

3.16.19 Install outside access hatches.

3.16.20 Inspect area for cleanliness.

3.16.21 Install end bells.

3.16.22

3.16.23

3.17 Testing

3.17.1 Motor

A. Testing shall perform the following tests:

A. Stator insulation resistance (IEEE 43) testing at 2500 V.

B. Rotor insulation resistance (IEEE 43) testing at 500 V.

C. Stator polarization index at 2500 V.

D. Field pole drop with 120 VAC.

B. Stator winding resistance (expected value: 0.0193 ohm @ 25O C).

C. Rotor winding resistance (expected value: 0.2114 ohm @ 25O C).

D. RTD resistance (10 ohm copper).

E. Slip ring runout (< = 0.005 inches).

F. Initial tests to identify as found conditions to include insulation resistance, polarization index, field pole drop, air gap, etc. The Contractor shall perform these tests prior to doing any cleaning of the motors. This will provide an indication of the current health of the motors.

G. Insulation resistance measurements shall be taken after major steps in cleaning, and after completion of the work. All readings are to be recorded on relevant inspection sheets along with temperature of the winding.

H. Post-cleaning tests shall be performed right after the motor has been cleaned. The same tests performed during initial testing shall be repeated to verify motor has not been damaged. Results are expected to improve. However, if results have gotten worse, notify the Government.

Investigate the possible reason for the negative results.

I. Final tests to be completed after painting and motor shifted back. Tests included shall be the same tests performed during the initial tests. These results will be used as the new baseline for the motor. See Verification and Acceptance criteria.

3.17.2 Checking Journal Bearing Radial Clearance Fan, Front (Coupling), Rear (South) Bearings

A. The bearing wear shall be checked without disassembling the bearing by using a hydraulic jack and dial indicators. A comparison of the previously taken and current lift clearances will give an indication of any bearing wear. See table below.

B. Two dial indicators, mounted on the top of the bearing housing, shall be used to measure shaft movement. One indicator shall indicate movement at the end of the top pad on the inboard side of the bearing, and the other shall be placed to do the same on the outboard side. A hydraulic jack with a calibrated and certified gauge reading either pressure or total load shall be placed in a convenient location as close to the bearing as possible. For the fan bearing, install a hydraulic jack with a calibrated and certified gauge reading either pressure or total load as close to the fan end of the bearing as possible. The dial indicators shall be set to zero. Using the jack, lift the shaft vertically at a slow enough rate so that the lifting pressure or force and the dial indicators can be monitored and recorded simultaneously.

C. As the lifting pressure initially increases, there will be little or no dial indicator movement until the lifting force equals the weight of the load on the bearing. At this point the shaft will lift through the journal bearing clearance with little or no additional hydraulic pressure until it pushes up hard against the top pad. Record the dial indicator readings at this point.

Increasing the pressure will produce additional small increases in the dial indicator readings as parts of the bearing and housing begin to deform, this action should be avoided. Average the two dial indicator readings to obtain the journal bearing lift clearance; it should be 0.02 to

0.03 inch. Record clearance on relevant inspection sheet.

D. Build a small H frame using I-beams to support the hydraulic jack prior to jacking shaft.

E. For the rear motor bearing only, the oil drip catcher on the end of the bearing shall be removed to provide clearance for the hydraulic jack.

F. For the fan bearing only, remove junction boxes and conduits on floor next to the bearing pedestal to make a clear space for hydraulic jack.

3.17.3 Checking Journal Bearing Thrust Clearance Fan Bearing

A. Check the total end float of the thrust bearing in the cold condition.

B. The bearing wear shall be checked without disassembling the bearing by using a hydraulic jack and dial indicators. A comparison of the previously taken and current thrust clearance will give an indication of any bearing wear. See Table 1.

C. Mount a dial indicator on the fan shaft so that it can indicate on the motor end of the bearing housing. Using a hydraulic jack to apply force to the fan end of the shafting, move it toward the motor until the end of travel is indicated by the dial indicator. Once the end of travel is indicated, do not apply additional force. Zero the dial indicator, then release the jacking pressure. Observe the indicator reading. Move the shafting toward the motor again until the dial indicator again reads zero.

Release the jacking pressure and observe the indicator reading. It should read the same as before and indicates that the shaft is in its natural position at the motor end. Set the dial indicator to zero. Install the jack on the motor end of the shafting and move it toward the fan end until the end of travel is indicated. Note this reading on the indicator.

Release the jacking pressure and record the new reading. Jack the shafting toward the fan again until the same end of travel reading is obtained then release the pressure. The dial indicator should return to the previous reading and the shaft will be in its natural position at the fan end. The reading on the dial indicator is the total end float, or clearance, between the thrust collar and the faces of the thrust condition.

D. Record clearances on provided inspection sheets.

Table 1

07/1983: Bearing Clearances without Fan Blades

Fan Radial Clearance Thrust Clearance

Motor Rear Motor

Bearing Front Motor

Bearing Fan Shaft Bearing

1 0.026 0.024 0.021 0.025

2 0.019 0.024 0.028 0.023

3 0.030 0.028 0.021 0.019

4 0.023 0.029 0.020 0.031

5 0.028 0.030 0.022 0.025

6 0.025 0.022 0.026 0.027

Table 2

10/2010: Bearing Clearances with Fan Blades

Fan Radial Clearance Thrust Clearance

Motor Rear Motor

Bearing Front Motor

Bearing Fan Shaft Bearing

1 0.0265 0.0150 0.0145 0.0265

2 0.0200 0.0150 0.0095 0.0245

3 0.0290 0.0165 0.0130 0.0225

4 0.0225 0.0150 0.0160 0.0320

5 0.0295 0.0300 0.0160 0.0267

6 0.0283 0.0217 0.0185 0.0290

3.17.4 Replace Field Pole Retaining Bolts

A. The Contractor shall replace the field pole retention bolts on each field pole. There are 40 poles total on a motor and each pole utilizes 4 bolts to hold it to the rotor spider. A pair of bolts are located on each side of the motor.

B. Field pole bolts and nuts will be provided by the Government.

A. Locking plates shall be inserted between the bolt and field pole.

Tabs/corners of the locking plate shall be bent up to prevent bolts from loosening.

B. Each bolt shall be torqued to 500 ft-lbs.

C. New torque stripes shall be applied on all bolts after they are tightened.

3.18 Verification and Acceptance

3.18.1 The work shall include cleaning the windings to remove buildup of grease and dirt, painting, and minor repairs with the intent of improving the insulation resistance and overall condition of the fan motor. The overall goal is to provide, at a minimum, ten years of reliable service. The following insulation resistances and polarization indexes relative to ground are minimum goals. The work shall be done on a best effort basis.

Stator Windings - Polarization Index >= 2.0

- Insulation Resistance >= 1000 Mohms (10 minutes) @ 40° C, 2500 V

Rotor Windings - Polarization Index N/A

- Insulation Resistance >= 50 Mohms (1 minute) @ 40° C, 500 V

3.19 Submittals

3.19.1 General

The Contractor shall submit submittals/specifications to the Government for review and approval as requested throughout this Statement of Work. The Government will review submittals and provide pertinent notation within 10 days after receipt. Submittals will be returned to the Contractor with either

Contractor shall not proceed with work until the submittals have been approved by the Government.

3.19.2 Reports

A. Reports shall include Inspection Reports, Electrical Testing Reports, and Repair Reports for the motors.

B. The first Inspection Report shall address the machines condition as found and any necessary repairs that are required. The first Inspection Report shall include the first Electrical Testing Report, Inspection Sheets, and be submitted to the Government at the completion of the inspection period. The first Electrical Testing Report shall include the results of all initial testing.

C. At the completion of the project, a final report shall be submitted to the Government. The final report shall include the second Inspection Report and Repair Reports.

D. The second Inspection Report shall include the second Electrical Testing Report and a detailed description of the machines condition at the completion of the project. The second Electrical Testing Report shall include the results of the intermediate and final testing.

E. Repair Reports shall include a detailed description of all repairs, the reasons for these repairs, that is, the condition that necessitated the repair, and any recommended future maintenance or repairs that are a result of the machines condition/repair.

3.19.3 Required Submittal Summary

Table 3

No. Section Reference Submittal Description Due

1 3.2.2 List of Personnel 3 weeks prior to first site visit

2 3.1 Schedule 3 weeks prior to first site visit

3 3.3 Safety Plan 2 weeks prior to first site visit

4 3.9.3.E Varnish Specifications 2 weeks prior to first site visit

5 3.9.5.D Cleaning Solvent Specifications

1 week prior to cleaning

6 3.12.4.C Stator Shift (If different from suggested plan)

1 week prior to stator shift effort.

7 3.13.1 Cleaning Plan 1 week prior to cleaning

8 3.15.1 Painting Plan 1 week prior to painting

9 3.19.2.B Inspection Report After completion of initial electrical tests

10 3.19.2.C Final Report, Second Inspection Report, and

Repair Reports

2 weeks after completion of work

END OF STATEMENT OF WORK