Model Meaning: "PH" indicates an extension ring, and "7" indicates a nominal breaking load of 70kN.
Material: Made of steel with a hot-dip galvanized surface for excellent corrosion resistance and suitability for harsh outdoor operating environments.
Structure: Generally a one-piece forged ring, similar in shape to a U-shaped hanging ring, but the connection holes at each end may be designed differently to accommodate different hardware connections and length adjustments.
Main Dimensions: Ring diameter 20mm, hole diameter 16mm, ring length 80mm.
Technical Parameters: Nominal breaking load 70kN, weight approximately 0.4kg.
Application: Used for connecting insulator strings to hardware, between clamps and insulator strings, and between lightning conductors and pole towers. It is a universal connection hardware.
The PH-7 extension ring is commonly referred to as the PH-0780, where "07" represents a breaking load of 70 kN and "80" refers to the ring length of 80 mm. It is manufactured from round steel butt-welded or forged as a single piece, forming a ring-shaped structure. The ends of the extension ring can be connected to other hardware, with the connecting screws aligned in the same direction, making it a parallel ring. The galvanized surface enhances corrosion resistance and extends its service life. As a ring-shaped connection fitting, it is commonly used to connect insulator strings to hardware, between clamps and insulator strings, and between lightning conductors and towers.
First-time users of the PH-7 extension ring are especially advised to familiarize themselves with its usage specifications to ensure smooth installation.
Load Limitation
Although the breaking load of the PH-7 extension ring is 70kN, the actual operating load must be ≤49kN, representing 70% of the breaking load.
Installation Compatibility
Bolts must be tightened with double nuts to prevent loosening. When mating with the cup-shaped bracket, the clearance should be ≤1mm.
Environmental Contraindications
Cast iron versions are prohibited in coastal and industrial areas. Low-temperature alloy versions should be selected for environments below -20°C.
The PH-7 extension ring is primarily used as a connector in power lines, with the following applications:
Connection Compensation
Extending connections between insulator strings and between clamps and insulator strings to compensate for installation gaps or adjust length deviations.
Transmission Lines
Transition connectors between suspension strings and tension strings to transfer mechanical loads.
Pole Tower Transposition
Installed on tension insulator strings to meet the electrical clearance requirements of jumpers to the tower.
Standard hot-dip galvanized alloy steel ensures corrosion resistance during operation. However, extension rings with the "Z" suffix are prohibited from use in highly corrosive environments.
The PH-7 extension ring typically has a service life of 15-20 years. However, with long-term use, its lifespan will eventually expire. So how do you determine when an extension ring needs replacement? Consider the following three factors:
Rust depth
When the rust depth exceeds 1mm, the zinc layer is damaged, accelerating corrosion of the steel.
Deformation
When the main body deformation exceeds 5%, the ring will bend under tension or compression, or the aperture will become out of round.
Low-temperature embrittlement
When temperatures below -20°C are below -20°C, it is prone to breakage if the low-temperature alloy is not used.
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