Arc tracking

Key properties of alkyds are dimensional stability, colorability, and arc track resistance. Chemical resistance is generally poor. 

The heat and flame resistance coupled with good electrical insulation characteristics, which includes in some grades good arcing and arc tracking resistance, has led to PPS replacing some of the older thermosets in electrical parts. These include connectors, coil formers, bobbins, terminal blocks, relay components, moulded bulb sockets for electric power station control panels, brush holders, motor housings, thermostat parts and switch components. 

The cycloaliphatic resins also are clearly superior in arc resistance and arc track resistance. This has led to applications in the tension insulators, rocket motor cases and transformer encapsulation. 

Alkyd molding compounds, when molded into finished parts, may have excellent arc resistance (180 sec. minimum) and excellent arc track resistance. Other good electricals such as dielectric strength and insulation resistance can be obtained. The filler combinations may also result in excellent dimensional stability and outstanding retention of electrical and physical properties after exposure to elevated temperatures (450°F.) for long periods of time. Water absorption values are extremely low, which helps to maintain electrical values. 

Parts molded from melamine compounds have a hard scratch resistant surface, practically no odor or taste, good electrical properties, fair arc track resistance, decorative appearance, and color fast characteristics. 

The specific gravity range is from 1.45 to 2.00. The principal use of melamine compounds has been in the dinnerware field. They are widely used in electrical switch gear applications where arc track resistance is very important. In some cases the melamine phenolic compounds are used to produce electrical switch gear where arc track requirements are not so severe. Other applications are ignition systems (distributor cap), housings, and other decorative applications. 

The nonaromatic nature of these maicrials provides for improved uv resistance and arc-track resistance compared to conventional epoxies The best properties arc generally achieved with anhydride and phenolic curing agents. 

Alkyds are formulated from polyester resins, cross-linking monomers, and fillers of mineral or glass. The unsaturated polyester resins used for thermosetting alkyds are the reaction products of polyfunctional organic alcohols (glycols) and dibasic organic acids. Key properties of alkyds are dimensional stability, colorability, and arc track resistance. Chemical resistance, however, is generally poor. 

The cycloaliphatic epoxy resins are characterized by the saturated ring in their chemical structure. They are almost water-white, very low-viscosity liquids. They provide excellent electrical properties such as low dissipation factor and good arc-track resistance, good weathering, and high heat distortion temperature. They are also free of hydrolyzable chlorine, sometimes present in DGEBA resins, which adversely affects certain electronic applications. 

PFA does track arc as many other pol5miers do. Arc tracking refers to the formation of a carbonized track on a wire insulation that forms a path for conducting electricity. PFA has been tested by ASTM D495 and exhibited no arc tracking over the 180 second duration of the test. 

PPS, either PA-66 or PA-MXD6 and Mg(OH)j tensile strength, arc tracking, and heat resistance Dubois et al., 1993... 

HVTR High voltage arc tracking rate Measures arc tracking rate on sample surface Rate in in/minute that a tracking path can be produced on the sample sruface imder standardized electrical stress... 

Uses Rame retardant, smoke suppressant used for reduced afterglow and arc/track in jacketing and insulation for plenum and riser cables, wall coverings, urethane foams, intumescent coatings and belting Properties Wh. ultrafine tree-flowing powd. 2-3 avg. particle size 99.9%... 

Another group of epoxy resins, the cycloaliphatics, is particularly important when superior arc track and weathering resistance are necessary requirements. A distinguishing feature of cycloaliphatic resins is the location of the epoxy group(s) on a ring structure rather than on an aliphatic chain. Cycloaliphatics can be produced by the... 

Filler improving wet and dry arc-track resistance and flame retardance... 

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