U70BLD External Double-shed Type Glass Insulators IEC Standard for High Voltage Lines
Product Overview
● Model: U70BLD
• U Refers To Disc Suspension Insulator
• B For Ball And Socket Type
• L Stands For Long Steel Foot
• D Stands For Double-shed Type
● Type: External Double-shed profile Toughened Suspension Type
● Rated mechanical load: 70kn (about 7 tons)
● Purpose: Widely applicable as insulation support for medium and high voltage transmission lines and substation equipment, capable of stable operation under various climatic conditions.
● The product model is in accordance with GB/T 7253-2005 and JB/T9683-2012
● The connection structure is in accordance with GB/T4056-2008(IEC60120:1984,MOD) and BS 3288 part lll.
● According to customer requirements, the locking pin can be either W-pin or R-pin.
● If there is no special instruction, W-pin is used for U70~U120,Other uses R-pin.
key parameters
|
IEC designation |
|
U70BLD |
|
QOCI Type |
|
UG70B146/450D |
|
Mechanical failing load |
kN |
70 |
|
Nominal Diameter D |
mm |
280 |
|
Nominal Spacing P |
mm |
146 |
|
Creepage distance L |
mm |
450 |
|
Socket coupling |
mm |
16 |
|
Wet power frequency withstand voltage |
kv |
45 |
|
Dry lightning impulse withstand voltage |
kv |
120 |
|
Power frequency puncture voltage |
kv |
110 |
|
Radio interference voltage(10kV 1MHz) |
μv |
50 |
|
Corona visual test P/C |
kv |
18/22 |
|
Power frequency electric arc voltage |
ka |
0.12s/20ka |
|
Impulse puncture voltage |
P.U |
2.8 |
|
Net weight per unit |
kg |
5.4 |
Structure and materials
-
Material characteristic
• High mechanical strength: The U160BL's mechanical and electrical failure load can reach 160KN due to the metal materials of the iron cap and steel base and the properties of the tempered glass itself.• Excellent insulation performance: tempered glass has good insulation performance, can effectively isolate the current between the wire and the earth, its power frequency wet withstand voltage up to 55KV, lightning impulse withstand voltage up to 140KV.• Strong corrosion resistance: iron cap and steel foot after anti-corrosion treatment, tempered glass also has good chemical stability, can resist a variety of harsh environmental conditions of corrosion and erosion.• Good self-cleaning performance: the glass surface is smooth, not easy to accumulate dirt, and can maintain a good clean state under rain wash, reducing the workload of manual cleaning. -
Shape size
• Height: The structural height is available in a variety of specifications, including 146 mm, 155 mm and 170 mm. The insulator's height can be selected based on the specific application scenario and voltage level.• Diameter: The diameter of the umbrella skirt of the glass insulator is larger, which can increase the creepage distance, improve the insulation performance, and reduce the possibility of flashover in a dirty environment.• Connection size: The connection size of the top iron cap and the bottom steel foot conforms to ISO cylindrical head structure, the head size is small, light weight, high strength, easy to connect with other fittings in the transmission line, and has good interchangeability.
Typical Installation Example
1.Basic Structure
Double-layer shed design: Two-tiered sheds (large and small) arranged alternately to increase creepage distance.
Material: Typically made of high-strength porcelain or silicone rubber composite.
Metal fittings: Hot-dip galvanized steel pins, ball sockets, etc., ensuring mechanical strength and electrical connectivity.
2.Key Features
Excellent pollution flashover resistance: The shed structure prevents continuous pollution buildup, enhancing insulation performance in contaminated environments.
Strong self-cleaning ability: Optimized shed angles facilitate rain washing, reducing contamination accumulation.
High mechanical strength: Suitable for high-voltage transmission lines (e.g., 110kV and above).
Superior weather resistance: UV-resistant, corrosion-proof, ideal for coastal, industrial, and heavily polluted areas.
3.Applications
Heavily polluted regions (e.g., chemical zones, salt fog areas, deserts).
High-voltage/ultra-high-voltage transmission lines (e.g., substations, suspension/tension strings on towers).
Harsh climates (heavy rain, ice/snow, sandstorms).
4.Comparison with Other Insulators
|
Type |
Double-Shed Insulator |
Standard Suspension Insulator |
Composite Insulator |
|
Pollution Resistance |
Excellent (dual sheds) |
Moderate |
Excellent (hydrophobic silicone) |
|
Mechanical Strength |
High (porcelain) |
High |
Medium-High (core rod dependent) |
|
Maintenance |
Low (self-cleaning) |
High (regular cleaning needed) |
Low |
|
Cost |
Medium-High |
Low |
Medium |
5. Selection Guidelines
Prioritize double-shed designs for pollution class ≥Ⅲ.
Consider mechanical load, altitude, and climate when selecting shed types (e.g., triple-shed, aerodynamic variants).
Contact Us
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Due to the time difference, we may not be able to reply to you immediately. We will reply to your email as soon as we start working.