Line Post Insulators ANSI 57-3
ANSI 57-3 Line Post With 737 mm Leakage Distance
ANSI 57-3 is a 15 inch porcelain line post for 45 kV class distribution and sub-transmission construction: 165 mm shed diameter, 381 mm height, 737 mm leakage distance and a 2,800 pound (12.5 kN) cantilever strength, at 11.1 kg per unit. The line post carries the conductor directly on the structure, which removes the swinging string and keeps the right of way narrow.
Key Benefits
- 737 mm leakage distance on a single unit for 45 kV class lines
- 12.5 kN cantilever strength for conductor side loads
- Rigid mounting removes conductor swing and narrows the right of way
- 311 mm dry arcing distance with 210 kV positive critical impulse flashover
Technical Features
- Wet-process porcelain, 165 mm shed diameter, 381 mm height
- 45 kV typical application voltage
- 125 kV low-frequency dry and 10 kV wet flashover voltage
- 200 uV maximum RIV at 1000 kHz with 30 kV test voltage to ground
Published Figures for This Design
The values below are the catalogued figures for this type. Where a figure your specification needs is not listed, ask and we will confirm it in writing rather than estimate it.
| Diameter (D) | 6 1/2Inches(165mm) |
|---|---|
| Height (H) | 15Inches(381mm) |
| Leakage Distance | 29Inches(737mm) |
| Dry Arcing Distance | 12 1/4Inches(311mm) |
| Net Weight Each | 24 1/2Pounds (11.1kg) |
| Cantilever Strength | 2,800Pounds(12.5kN) |
|---|
| Typical Application Voltage | 45kV |
|---|---|
| Low Frequency Dry Flashover Voltage | 125kV |
| Low Frequency Wet Flashover Voltage | 10kV |
| Critical Impulse Flashover Voltage, Positive | 210kV |
| Critical Impulse Flashover Voltage, Negative | 260kV |
| Test Voltage RMS to Ground | 30kV |
|---|---|
| Maximum RIV at 1000 kHz | 200μV |
Application Scenarios
- 45 kV class sub-transmission on narrow rights of way
- Urban and roadside distribution where swing clearance is limited
- Compact line construction on concrete and steel poles
Who It Is For
- Distribution utilities building compact lines
- Contractors working in constrained urban corridors
- Designers replacing pin type construction at higher voltages
Problems It Solves
- Conductor swing into trees and buildings on tight rights of way
- Pin type insulators reaching their voltage limit as a network is uprated
- Flashover on lines whose original leakage distance was under-specified
How This Design Differs From the Alternatives
Compared With ANSI 57-2 line post
Taller at 381 mm with 737 mm leakage against 559 mm, for 45 kV rather than 35 kV class construction.
Compared With ANSI 56-3 pin type
Same cantilever class but a post that bolts to the structure, giving more leakage distance and a higher application voltage than pin construction.
Specifying and Installing This Unit
- Confirm the conductor side load and wind load against the 12.5 kN cantilever rating
- Match the base stud or clamp arrangement to your crossarm before ordering
- Tie the conductor into the top groove without over-tightening the tie wire
- Keep to one post type along a line so spares stay simple
Questions About This Product
What voltage is 57-3 used at?
The typical application voltage is 45 kV. The final decision comes from your system voltage, pollution class and the basic impulse level you design to.
How is cantilever strength applied?
It is the transverse load at the conductor position. Combine wind on the conductor, line angle and any construction loading, apply your safety factor, and compare with 12.5 kN.
Can the mounting be adapted to our crossarm?
Send your crossarm and base fitting drawing with the enquiry and we will confirm what fitting arrangement can be supplied.
Why is the wet flashover figure so much lower than the dry?
Wet flashover is measured with the surface under standard artificial rain, which shorts much of the leakage path. It is the conservative figure to design against for exposed lines.
Which glaze colours are available?
Grey and brown. ANSI grey is specified to Munsell 5BG7.0/0.4 with defined tolerances.
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Request A Quote for Line Post Insulators ANSI 57-3
Send the quantity, the destination port and the standard you buy against. Routine test records ship with the goods and type test reports are available on request.