Tech Spec mow 3rd rail support insulators.pdf

MBTA MOW Specification – 3rd Rail Support Insulators

1. GENERAL

A. Support insulators shall consist of a base with a bonded cap, manufactured with molded fiberglass reinforced plastic material meeting the properties specified herein. The cap shall contain bonded in place cap inserts meeting the material properties as specified herein. The complete assembly of base, cap, and inserts shall have design dimensions as shown in the Book of Standard Trackwork

Plans, with all additional dimensional details required to meet the performance criteria specified herein. Base and cap color shall be porcelain white, cap inserts shall be black.

B. The complete insulator assembly, by design is intended to support the contact rail system and to provide electrical isolation. The support insulator shall provide a minimum of 6-½ inches of external distance from the charged contact rail to electrical ground or the insulator fasteners. Insulators shall be rated for a nominal voltage of 750 volts DC, and a maximum regenerative potential of 900 volts DC.

C. The fiberglass reinforced molded base and cap shall be generally free from molding defects consisting of, but not limited to, chips, pits and porosity that may affect the structural or electrical performance. There shall be no surface cracks or crazing in the critical location of the insulator as denoted in the Plans.

Outside of the critical location, surface cracks shall not exceed ¼ inch in length, crazing shall not exceed 1 inch diameter. Surface cracks and crazing shall be cause for rejection if they occur greater than two times on any one product or if two defects occur within 2- ½ inches from each other.

D. Each insulator shall be imprinted with the manufacturing lot number, batch and manufacturing date. Imprint shall be legible for the expected service life of the insulator. The base shall also be imprinted to include the type of contact rail that will be supported, and the dimensional height of each insulator stand.

2. SUPPORT INSULATOR BASE AND CAP

A. Base and cap material shall be composed of 30% polyester (including coloring) accelerator, catalysts, etc., 30% fiberglass, and 40% aluminum trioxide, UL recognized, and shall meet the following properties. A report shall be submitted demonstrating compliance with these properties prior to production. Production product thereafter shall be certified to have been manufactured using the same material formulation and manufacturing process as previously approved.

Flexural Strength, psi 20,000 min ASTM D 790

Flexural Modulus, psi 1.0 x 106 min ASTM D 790

Tensile Strength, psi 17,000 min ASTM D 638

Tensile Modulus, psi 9.0 x l05 min ASTM D 638

Compressive Strength, psi 20,000 min ASTM D695

Impact strength, ft-lbs / in 20 min ASTM D 256

Perpendicular Dielectric

Strength, volts/mil 200 min ASTM D 149

Arc Resistance, seconds 180 min ASTM D 495

Water Absorption, 24 hours at 23 deg C

% weight change

0.3 max ASTM D 570

Flame Spread 60 max ASTM E 162

Flame Resistance V-0 rating UL 94

Tracking Resistance, at 2500 volts 600 minutes min ASTM D 2303

Heat Distortion, at 264 psi Minimum 180 degrees C ASTM D648

B. Cap insert material shall meet the following properties. A report shall be submitted demonstrating compliance with these properties prior to production.

Production product thereafter shall be certified to have been manufactured using the same material formulation and manufacturing process as previously approved.

Tensile Strength, psi 7200 min ASTM D 638

Compressive Strength, psi at 10% compression 7,000 min ASTM D 695

Dielectric Strength

Volt / mil 150 min ASTM D 149

Arc Resistance, seconds 125 min ASTM D 495

Volume Resistivity

Ohm-cm 6 x 1014 min ASTM D 257

3. SUPPORT INSULATOR ASSEMBLY QUALIFICATION TESTING

A. Three insulator assemblies shall be electrically tested as follows:

1. Insulator shall be cleaned, dried and placed upright on a table suitable for electrical testing. The insulator shall then be subjected to a voltage potential of

1,000 Volts DC from the bottom of the base to the top of the cap using wet clay pads containing the anode and cathode leads. The circuit shall be capable of simultaneously displaying resistance. The voltage shall be maintained for no less than 1 minute during which the insulator assembly shall exhibit not less than 100 megohms resistance.

2. Insulator shall be immersed in water at 22 OC for not less than three minutes.

The insulator shall be removed from the water and placed upright on a table suitable for electrical testing. The insulator shall then be subjected to a voltage potential of 2,200 Volts DC from the bottom of the base to the top of the cap using wet clay pads containing the anode and cathode leads. The voltage shall be maintained for no less than 1 minute without electrical breakdown.

3. Insulator shall be immersed in water at 22 OC for not less than 72 hours. The insulator shall be removed from the water and placed upright on a table suitable for electrical testing. The insulator shall then be subjected to a voltage potential of 1,000 Volts DC from the bottom of the base to the top of the cap using wet clay pads containing the anode and cathode leads. The circuit shall be capable of simultaneously displaying resistance. The voltage shall be maintained for no less than 1 minute during which the insulator assembly shall exhibit not less than 7 megohms resistance.

B. Two insulator assemblies shall be mechanically load tested as follows:

1. The insulator shall be set vertical upright and bolted to a support surface using

½ inch bolts with one 1-½ inch diameter flat washer. A lateral load of 1,200 pounds shall be applied to the inside edge of the rail seat length to produce a shear force across the insulator cap. The load shall be held for not less than 1 minute and then increased to 1,500 pounds for an additional 10 seconds. The entire support insulator assembly shall be visually inspected without the aid of magnification after the load has been removed. There shall be no evidence of cracking of the any component of the insulator assembly.

2. The insulator shall be set vertical upright and bolted to a support surface using

½ inch bolts with one 1 ½ inch diameter flat washer. The insulator shall then be vertically loaded along a 2-inch line contact offset to an outer edge of the rail seat producing a torque like action between the cap and the base interface.

The load shall be held at 4,500 pounds for not less than one minute. The insulator cap shall not be displaced from the base due to the load application.

4. SUPPORT INSULATOR ASSEMBLY PRODUCTION TESTING

A. Three samples shall be taken from each 500 insulator assemblies produced. All three samples shall be tested as described in articles 3A1, 3A2, 3A3 and 3B1. If any insulator assembly fails any one test, additional samples shall be taken and re-tested for that test.

A second sampling failure shall constitute failure of the entire 500-piece lot.

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LBFoster Rail Business

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Transit Products Division

Suwanee, Ga 30024

M.O.W.

DIVISION

85 LB. COMPOSITE

CONTACT RAIL DETAILS

Contact Rail Insulator Stands

"B

"A"

Equals "A" plus 1-5/8"

RAISED LEGIBLE

INFORMATION BOTH

SIDES TYP.

SEE NOTE 6

T Y

P E

H E

IG

H

T

RAISED LEGIBLE

INFORMATION BOTH

SIDES TYP.

SEE NOTE 6

CRITICAL SURFACE AREA

AROUND PERIMETER OF BASE.

ONE INCH HORIZONTAL AND

VERTICAL FROM RADIUS.

SEE NOTE 5

NOTES:

1) ALL DIMENSIONS IN INCHES, UNLESS NOTED

OTHERWISE.

2) REFER TO "INSULATOR STAND SIZING CHART"

FOR VARIOUS INSULATOR DIMENSIONS USED

ON MBTA SYSTEM. THE 8-1/8" HEIGHT

INSULATOR STAND FOR 85C CONTACT RAIL IS

SHOWN HERE.

3) CAP AND BASE COMPONENTS SHALL BE

FIBERGLASS REINFORCED PLASTIC PER MBTA

SPECIFICATION. CAP INSERT SHALL BE PER

MBTA SPECIFICATION.

4) ALL COMPONENTS SHALL MEET MBTA

SPECIFICATION FOR MATERIAL PROPERTIES

AND TESTING REQUIREMENTS.

5) THE CRITICAL SURFACE AREA AROUND THE

PERIMETER OF THE BASE SHALL CONTAIN NO

SURFACE CRACKS OR CRAZING, PER THE MBTA

SPECIFICATION.

6) BASE OF STAND SHALL BE EMBOSSED WITH

THE TYPE OF CONTACT RAIL IT IS DESIGNED

FOR, AND THE HEIGHT OF THE INSULATOR.

REFER TO "INSULATOR STAND SIZING CHART".

IT SHALL ALSO INCLUDE THE MANUFACTURER

LOT NUMBER AND BATCH.

7) INSULATOR STAND COLOR SHALL BE

PORCELAIN WHITE.

*NOTE: BASE OF 84C TO BASE OF 115# SHOULD BE 8-1/2", THEN FACTOR FOR FASTENING SYSTEM FOR HEIGHT OF STAND. BASE OF 85C TO 115# SHOULD ALWAYS BE 7-3/8".