Procedures_New_80574001.doc

PORTSMOUTH NAVAL SHIPYARD

500 KW “NEW DESIGN” SSMG

COMMUTATOR MANUFACTURE PROCEDURE

COMMUTATOR REFURBISHMENT PROCEDURE

“NEW DESIGN”

The commutator shall be rebuilt in accordance with the following instructions. All materials shall be as specified. Equivalent materials may be used if approved by Portsmouth Naval Shipyard in writing or via E-mail. The commutator manufacturer is responsible to provide certified records including signatures required by this instruction, that the commutator has been rebuilt in accordance with this instruction. The manufacturer shall provide a copy of all spec or data sheets for all materials used during the manufacture of the commutator with the final certification package. Failure to meet any requirements shall be cause for rejection.

NOTES:

1. NO SILICONE OR SILICONE CONTAINING PRODUCTS SHALL BE USED IN THE REFURBISHMENT OF THE COMMUTATOR.

2.

ALL METERS AND MEASURING INSTRUMENTS USED FOR CERTIFICATION OF DATA SHALL MEET THE REQUIREMENTS OF ISO-10012-1 “QUALITY ASSURANCE REQUIREMENTS FOR MEASURING EQUIPMENT” AND/OR ANSI-Z540-1 “GENERAL REQUIREMENTS FOR CALIBRATION LABORATORIES AND MEASURING AND TEST EQUIPMENT”.

3. INSPECTION OF THE COMMUTATOR COMPONENTS AND COMPLETED ASSEMBLY SHALL BE PER ISO 9001/ANSI Q9001. INSPECTION AT ORIGIN WILL BE ACCOMPLISHED FOLLOWED BY INSPECTION AND ACCEPTANCE AT DESTINATION.

4. THE GENERATOR THAT UTILIZES THIS COMMUTATOR HAS A DUST SEAL THAT RIDES ON THE COMMUTATOR SURFACE ADJACENT TO THE BRUSH-RIDING SURFACE. IN ORDER TO MAINTAIN THIS SEALING SURFACE ADDITIONAL DIMENSIONS AND DATA PERTAINING TO THE SEAL LOCATION AND BAR DIAMETER WILL BE REQUIRED PRIOR TO DISASSEMBLING THE COMMUTATOR. THE MICA MUST NOT BE UNDERCUT IN THE SEAL RIDING AREA. CONTACT PNS IF FURTHER INFORMATION IS REQUIRED.

a) The commutator GFM carcass will be provided to the contractor after being removed from its shaft by Portsmouth Naval Shipyard. The commutator is for a General Electric 500 kW (New Design) DC generator, 210 - 355 volts, 1200 RPM. The following data is provided for informational purposes only.

Number of Segments - 152

Mica segment thickness- .040"

Armature Coil Wire Size - .080" x .300"

No of Wires per slot - 8

Diameter (brush surface) 19 35/64" Min

Diameter (dust seal surface) 19.925" +/- 0.005” After assembling the commutator, clean up the dust seal surface in a lathe the minimum amount necessary to obtain a total indicated runout (TIR) of less then .003”. The final outside dimension of the surface shall be not less than 19.680” and not more than 19.880”.

Length of active surface 10 5/16"

Bar length - 13 3/32"

Front V-Ring Proj. - 1 7/8"

Rear V-Ring Proj - 1 7/8"

Riser Type - Double Inserted

Dia. over risers - 29.50" (As Folded)

Commutator weight - 854 LB

Keyway - none

Shaft (commutator mounting surface) Diameter:

Riser end (8.999 - 9.000"); Front end (8.989"- 8.990")

Commutator Bore Diameter: Riser end (8.996 - 8.997");

Front end (8.987 - 8.988")

b) The commutator shall be completely stripped of all insulation material prior to replacing copper segments and insulation (including any varnish).

c) All commutator copper shall be new. Replacement commutator bars shall be manufactured from copper bar stock in accordance with the Copper Development Book, silver bearing type UNSC-11600 with 25-30 troy ounces of silver per ton. Copper bar hardness shall be at least 70 Rockwell F and have a tensile strength of not less than 30,000 PSI. Riser material shall be oxygen free silver bearing type UNSC-10700 copper. Risers shall be brazed to the bars with BCuP-5 brazing rod per Fed Spec QQ-B-654 without the use of flux. The brazed joint shall have excess material removed as required to ensure that excess filler material does not interfere with the fit up of the completed assembly.

d) All the mica insulation shall be new. Segment insulation (between commutator bars) shall be inorganic bonded muscovite micapaper. The segment insulation shall be flush with the commutator segments in the area of the riser seal. The segment insulation shall be sub flush 1/16" to 3/32" on the brush riding surface. Commutator ground insulation and the V-ring insulation shall be pasted mica, type PMM, in accordance with NEMA FI-1. The thickness and the extent of all insulation shall be equal, as a minimum to the thickness and extent of insulation as found on the original commutator provided for rebuild. Each Mica V-ring and barrel shell insulator will be built in such a manner that it is one molded assembly consisting of built up layers that are scarfed or tapered to obtain uniform thickness when successive strips are lapped over in making the ring. V-rings consisting of two pieces with a joint at the apex of the V-ring are unacceptable.

e) Commutator steel parts shall be inspected for damage. Any damaged or missing parts shall be repaired or replaced. The V-ring barrel if replaced shall be manufactured from seamless steel tubing per ASTM A29, AISI 1020. The V-ring clamp rings if replaced shall be manufactured from carbon steel per ASTM A29, AISI 1040. Hot rolled seamless steel tubing per ASTM A-106 is acceptable for barrel replacement. AISI-4140, normalized, quenched & tempered to meet ASTM A-668 is acceptable for v-ring replacement.

Note: Repairs to steel parts shall consist of minor straightening, weld build-up, and plating in accordance with MIL-STD-2197. A bushing or sleeve shall not be used to repair over sized seating surfaces.

CLAMP RINGS AND BARREL INPECTED/REPLACED, MAT'L AS SPECIFIED:

SIGNATURE/DATE

f) V-ring studs shall be replaced with heat-treated and stress relieved alloy steel bar per AISI-4140. All nuts shall be replaced; the material for the nuts shall be at least SAE Grade 5 alloy steel. New locking tabs will be manufactured from 1/16” carbon steel plate. Note: The locking tabs will not be bent over by the commutator manufacturer. These will be bent at PNS after the commutator is mounted on a shaft and final torque has been applied.

ALL NUTS, STUDS AND LOCKTABS ARE NEW MAT'L AS SPECIFIED:

SIGNATURE/DATE

g) The inside and outside V-rings shall be banded with 3/8” wide B-staged glass banding. No Teflon will be used in this area. Glass band to extend from the face of the clamp ring to the face of the commutator bars. Glass banding shall conform to Mil-I-24178, such as Fibertek Inc. RES-I-GLASS B-0322-F, or equivalent. The bands shall be built up on the V-rings to a level that will completely seal any opening at the V-ring where grit or carbon dust could become lodged on the V-ring surface. NO STRING BANDING, GLASS WEAVE OR TEFLON TYPE BANDING SHALL BE USED.

GLASS BANDING PER MIL-I-24178 APPLIED AS DESCRIBED ABOVE:

SIGNATURE/DATE

h) The commutator steel mating surfaces (inside diameter) shall have a final dimension of: Riser end (8.996 - 8.997"); Front end (8.987 - 8.988"). Record actual dimensions below.

FINAL COMMUTATOR STEEL MATING SURFACE DIMENSIONS

RISER END: IN

FRONT END: IN

SIGNATURE/DATE

i) The commutator shall be spin seasoned after assembly. The commutator shall be seasoned at 1500-1550 RPM, at a temperature of at least 200(C for at least three five minute cycles. The maximum change in total indicator runout shall be 0.002 in.

COMMUTATOR SATISFACTORILY SPIN SEASONED:

SIGNATURE/DATE

j) The axial skew of the commutator bars shall be checked from the riser to the end of the commutator. Commutator bar axial skew shall not exceed 0.015-in. Excessive axial skew shall be corrected.

AXIAL SKEW IS LESS THAN .015 IN:

SIGNATURE/DATE

k) The commutator shall successfully pass a 400 VAC bar to bar test between the commutator bars. If the commutator does not successfully pass this test, it shall be repaired as necessary.

400 VAC BAR TO BAR TEST SAT:

SIGNATURE/DATE

l) Wrap several turns of bare copper wire securely around the commutator to short bars together and conduct a 3500 VAC Hi-Pot between the commutator bars and ground to ensure there are no grounds or shorts between the commutator and ground. If the commutator does not successfully pass this test, it shall be repaired as necessary.

3500 VAC HI-POT SATISFACTORY:

SIGNATURE/DATE

m) Measure for one minute the insulation resistance to ground of all the commutator bars connected together. The minimum insulation resistance value shall be 10,000 megohms. Log below the actual megohms (data such as infinity or greater than 100 megohms is unsatisfactory. Greater then 10,000 meg-ohms is an acceptable reading) If the commutator does not successfully pass this test, it shall be repaired as necessary.

SIGNATURE/DATE:

n) The commutator outside diameter shall be machined to be concentric with the inside diameter of the mounting sleeve within 0.003 inch TIR. The bar-to-bar runout shall not exceed 0.0003 inch bar-to-bar. Log actual concentricity and bar-to-bar runout in the table below.

Concentricity of the commutator surface with respect to the mounting sleeve and commutator bar-to-bar runout:

one inch from front middle one inch from dust seal

On the dust seal surface

Required: Concentricity less than 0.003-in. TIR, bar-to-bar runout less than 0.0003 in. TIR

SIGNATURE/DATE

o) The commutator manufacturer shall stamp or etch mark the outside V-ring (steel portion) in a visible location with a unique serial number consisting of the abbreviated company name, two digit month and two digit year date code of when the commutator was rebuilt. Verify data below.

Commutator Serial Number:

Company Abbreviation/Two Digit Month/Two Digit Year

SIGNATURE/DATE

p) All exposed steel parts (with the exception of bore to shaft mounting surfaces) shall be coated with air dry varnish per MIL-I-24092 Grade CA (NON SILICONE) or baking varnish per MIL-I-24092 Grade CB (NON SILICONE). NO PIGMENTED OR COLORED VARNISHES AND RESINS ARE ALLOWED. Ensure that the commutator serial number remains visible.

q) After completion of all of the above work, the commutator shall be balanced to 5 ounce-inches or less.

FINAL BALANCE DATA:

Required:

≤ 5 0Z-IN

Actual:

SIGNATURE/DATE

r) The commutator manufacturer shall cover the commutator bore/mounting surfaces with a non-silicone rust inhibitor such as Cosmoline or "Dolph Lamination Coater With Orange Tracer". The completed commutator shall be wrapped in plastic or other suitable packing material to keep dirt and grit from the finished unit. The commutator shall then be installed in a suitable crate and braced as required to prevent movement and damage to the commutator during shipping. A copy of all certification data shall be provided in the shipping crate.

Enclosure (2) Part (2)