Third Rail Heaters Technical Spec rev2.pdf

THIRD RAIL HEATER SPECIFICATION

October 5, 2019

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Part 1 - General

1.01 Scope

A. This specification outlines design and operational requirements for third rail heaters with power limiting capabilities.

B. Polymer heating cables shall not be acceptable to the Authority. The heaters shall be a:

• Parallel circuit design

• Metal / alloy fiber composite heating element

• Positive temperature coefficient such that wattage decreases as sheath temperature increases and conversely wattage increases as sheath temperature decreases will not be acceptable. Heaters must be constant wattage type.

C. The heaters are to be installed on 85 pound / yard composite third rails.

D. Heaters shall be reusable in that they can be removed from the contact rail when heater is at ambient temperature and re-installed.

E. Heaters shall be able to directly replace existing Authority installed polymer type heaters without alterations to fuses or contactors.

The requirements specified herein apply to third rail heaters specifically designed for the purpose of deicing contact rails on mass transit systems.

1.02 Applicable Vendor Qualifications

The manufacturer shall have and submit documented evidence of at least three (3) years operating experience in providing contact rail heaters of the construction specified

Heaters shall be furnished by a manufacturer who is regularly engaged in the production of contact third rail heaters of the construction specified herein for transit systems. Manufacturer shall have successfully manufactured, terminated, and operated a complete heater assembly of the construction specified herein, under the Authority’s supervision, for a minimum of one heating season without failure.

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1.03 Codes and Standards

• The heaters shall be tested in accordance with test program as outlined in the current revision of IEEE 515.

• Manufacturer’s Quality Assurance Program must be certified by an independent auditing firm to ISO 9001

• IEEE 16

• IEEE 515

1.04 Submittals

A. At the time of Bid, the manufacturer shall submit complete technical data on the contact rail heater design. Submittal shall include, but not be limited to, dimensions, drawings, catalog cut sheets, and descriptions of all materials, including cables, terminations, channels, and fastening clips.

Part 2 - Product

2.01 Construction

A. Heater

1. The heater element construction shall have of a minimum of two 10 AWG nickel-plated copper conductors in a parallel circuit design.

2. The contact rail heater shall consist of two (2) parallel nickel-plated copper conductors. Each of the two (2) conductors is insulated with PFA. Over these two

(2) insulated conductors are laid parallel, a PFA binder insulation pairing jacket is extruded to form a parallel core. A Nichrome resistance wire is spirally wrapped around the core, followed with a PFA Teflon jacket. The heater assembly is covered with a braid of nickel-plated copper with a minimum of 80% coverage followed by an overall PFA jacket (outer sheathing) - silicone outer sheathing shall not be accepted. The heater assembly is supplied in lengths of 52 feet 6 inches plus lead wires with a four (4) foot skive length. Each skive shall have a solder connection.

3. The contact rail heater wire leads shall be No. 8 AWG, 37/24 strand, single copper cable with a heat resistant dielectric insulation, rated 2000 volts Transit Wire.

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B. Marking and Identification

1. The following information shall be continuously printed on the outside surface of the heater:

• Manufacturer’s Name

• Voltage Rating

• Wattage Per Foot

C. Terminations

1. Heater terminations shall be able to be performed in the field by using standard commercially available hardware.

D. Containment Channel

1. Heater shall be held to the contact rail by thermally rated insulation fiberglass channels affixed to the rail by stainless steel spring clips. The insulation shall exhibit excellent thermal insulation and water-resistant properties. This insulation, channel, and clip combination provides a more uniform and applied force of the heater to the rail. The fiberglass channel shall have thickness necessary for proper rigidity in holding the heater against the contact rail. Channel length shall be three

(3) feet to four (4) feet.

E. Spring Clip

1. Insulated containment channel with heater shall be held tight against the contact rail by means of stainless-steel spring clips. They shall be minimum, twenty (20) gauge (0.040 inches thick) by one-and-one-eighth 1-1/8) inches wide, flat spring steel.

2. Spring clips shall be available for 85-pound composite contact rail.

2.02 Warranty

A. Length of Life

1. All material included under this specification shall be warranted against defects in material or workmanship for a period of five (5) years.

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Part 3 – Testing

3.01 Factory Tests

A. All heaters shall be tested at the manufacturer’s plant prior to shipment as specified herein.

B. Function Test

1. Power shall be allied at rated voltage to ensure heaters operate properly.

C. Megger Test

1. All heaters shall be capable of withstanding Megger test ≥ 4MΏ @ 1000VDC, applied for one (1) minute between the heating conductor and the metallic braid.

The Megger test should be measured on the sample while in the water solution specified in 3.01F.

D. Hi-Pot Test

1. All heaters shall be capable of withstanding Hi-pot test ≤ 2mA @ 1000VDC, applied for one (1) minute between the heating conductor and the metallic braid. The Hi-pot test should be measured on the sample while in the water solution specified in 3.01F.

E. Water Resistance Test

1. Every heater shall be immersed (except at termination’s or ends where the conductors are exposed) in water for a period of 4.5 minutes. Within one (1) hour after conditioning as above, the sample should be subjected to the dielectric test outlined in 3.01D.

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Part 4 - Execution

4.01 Installation

A. Contact Rail

1. Heaters will be installed on 85-pound composite rail.

2. Channel shall hold heater to third rail and be held firmly to the rail by insulation and stainless-steel spring clips as described above

3. Where an obstruction such as a third rail anchor or joint bar is encountered, the heater shall pass out of the channel and loop around the obstruction.