Austin Insulators Inc. Manufacturers of RF Insulators and Transformers.

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		Austin Insulators Inc. suppliers of RF insulators and transformers since 1933

Products: Self Supporting Base Insulator Description Specifications Notes		Austin Base Insulators for Self Supporting Radio Towers and Masts Austin Base Insulators for Self Supporting Radio Towers use ceramic in compression to bear the compression load and utilize continuous wound preloaded links to resist the individual leg uplift. In these bases, the resistance to shear load is derived from the compressive load and preload applied to the base. In addition to the standard range, designs can be provided for custom applications with extremely high electrical and mechanical working loads as well as high seismic load conditions. Special exact fit replacement bases, as substitutes for insulators by other manufacturers, are also available. Oil filled to eliminate Radio Frequency loss due to water condensation on internal surfaces. Additional benefits are elimination of 'hot spots' and easy detection of porcelain failure. Smooth insulator finish minimizes leakage and flashover due to surface contamination. Items listed are types recommended for new construction. Previously listed Austin types are available for replacement purposes. Insulators for higher mechanical and electrical loads are available. Please call, write, or e-mail stating your requirements. All insulators are supplied with adjustable lightning gap.

Specifications

Insulator Type	Number of Elements	Maximum Recommended Working Download (note 1)	Maximum Recommended Working Uplift (note 1)	Permissible Shear Load at Rated Uplift (note 2)	Preload	1 minute Drip Wet Withstand at 100kHz; Voltages KV RMS
Insulator Type	Number of Elements	Maximum Recommended Working Download (note 1)	Maximum Recommended Working Uplift (note 1)	Permissible Shear Load at Rated Uplift (note 2)	Preload	Standard Rainshield	High Voltage Rainshield
*A-4950 A-4950-C	1	25,000 lb 11,340 kg	17,500 lb 7,938 kg	680 lb 308 kg	25,000 lb 11,340 kg	32	44
*A-4938 A-4938-C	1	50,000 lb 22,700 kg	35,000 lb 15,900 kg	1,850 lb 840 kg	50,000 lb 22,700 kg	22	30
*A-4881 A-4881-C	1	75,000 lb 34,000 kg	52,500 lb 23,800 kg	2,400 lb 1,090 kg	75,000 lb 34,000 kg	71	99
*A-4729 A-4729-C	1	100,000 lb 45,400 kg	70,000 lb 31,800 kg	3,600 lb 1,630 kg	100,000 lb 45,400 kg	71	99
*A-3167 A-3167-C	1	150,000 lb 68,000 kg	105,000 lb 47,600 kg	6,300 lb 2,860 kg	150,000 lb 68,000 kg	71	99
*A-2812 A-2812-C	3	250,000 lb 113,400 kg	196,000 lb 88,900 kg	10,000 lb 4,540 kg	280,000 lb 127,000 kg	71	99
*A-2913 A-2913-C	3	375,000 lb 170,100 kg	280,000 lb 127,000 kg	15,500 lb 7,030 kg	400,000 lb 181,400 kg	71	99
*A-3782 A-3782-C	5	600,000 lb 272,200 kg	455,000 lb 206,400 kg	25,000 lb 11,340 kg	650,000 lb 294,800 kg	71	99
*A-4049 A-4049-C	6	900,000 lb 408,000 kg	600,000 lb 272,200 kg	42,000 lb 19,000 kg	900,000 lb 408,000 kg	71	99

* Identical insulator except it has a round base.

Notes:

Allows for a minimum Safety Factor of 3.
The permissible shearloads stated above assume that the insulators are worked at their stated recommended maximum working uplifts. If your required working uplift is lower than that given in the table above, a higher shearload is permissible. The following formula will enable the new maximum permissible shearload to be calculated.

Example: For insulator type A-4881-C and a required working uplift of only 30,000 lb.,

The 4,800 lb. represents the permissible shearload of this insulator when the working uplift requirement is 30,000 lb.
The drip wet figures above are a minimum achieved with the insulator standing directly on the ground plane. Higher voltages can be expected with the insulator installed on a pier.
All insulators can be fitted with a high voltage rainshield as an optional accessory to improve the voltage rating.