Corona Shielding Ring For Insulator , Grading Ring Insulator For
|Standard||DIN,ISO, Non-Standard or according to customers’requirement|
|Applications||Power Hardware, Cable Hardware,High Voltage Test etc|
|Packing details||International standard package such as carton wooden or according
to your requirements|
|Delivery time||According to the quantity of products but will as soon as possible|
L/C, T/T, Western Union
30% TT before the produce, 70% before the shipment
|Place of Origin||Jiangsu,China|
Corona&Shielding Ring for Insulator is used to very high
voltage power transmission insulators and switchgear, and on
scientific research apparatus that generates high voltages, for
lower its maximum values below the corona threshold, preventing
What is Grading Ring?
Compared to electric porcelain insulator, composite insulator is
featured with high intensity, light weight, high wet-flashover and
flashover voltage, easy operation maintenance, strong ability of
impulse withstand, widely applied to transmission line suspension
string, and has spread application in tension string in recent
years. Surface field distribution and potential distribution for
composite insulator without corona ring is greatly uneven, due to
composite insulator structure characteristics and high resistivity
feature of silicon rubber, surface field density is highest at
mandrel and steel cap joint, distribution voltage is highest at
first umbrella dress near high voltage end. Exorbitant surface
field density not only generate corona discharge, affect
transmission line electromagnetic environment, produce audible
sound pollution, but also cause strong electric erosion, causing
further insulator aging. Corona ring installation is the normal
solution to the problem of uneven potential field density
distribution at insulator high voltage end. Installation of corona
ring helps to transfer maximum field density from insulator surface
to corona ring surface, thus effectively improves electric field
distribution on insulator surface.
How Corona Ring Works?
Corona discharge is an electrode-outer air current flow that
happens (among other) in high-voltage power lines. One way to
reduce corona discharge is using corona rings - a ring made of
thick metal rod positioned orthogonal to the wire, earthed and
mounted to the power line post.
Corona discharge damages insulators and may produce breakdown
products which can cause catastrophic insulation failure. If
electric field at a certain point in air is strong enough,
electrons will be stripped from the atoms and make the air a
conductive plasma instead of an insulator. An object with high
voltage and a small curvature (wire, sharp points) enables a field
of enough high strength, forming a conductive layer of air, which
is then surrounded by normal insulating air. In this case the
conductive layer can increase in size (usually in one direction)
until it forms a complete conductive path to another object, and
then a huge arc-shaped current flow. Even a non-arc-shaped field
can form a corona discharge. For that a conductive layer of plasma
stops expanding and stays around the wire, ions in the plasma layer
are repelled into neutral air and drift slowly in the air until
discharged on another object, which is still a current flow yet
Corona Ring Material
Aluminum, steel and copper are main material for Corona Ring and
The corona ring packing can be done by wooden case and cartons.
1). Wooden Packing:
Wooden packing suitable for heavy weight corona rings. For export,
Fumigation Certificate will be necessary when case is made of solid
1.No bark allowed on wooden package.
2.Ship fumigated wooden package as soon as possible, ensure
separate storage and segregation with non-fumigated wooden
3.Validity of the certificate of fumigation is 21 days.
Inquire local ship agency whether fumigation is necessary every
time after learning the lot package material, booking with a
certain answer. Method of wood case fumigation include chemical
preparation method and heat treatment.
2). Carton Packing:
Carton Packing always light weight and convenient for moving by
hands. Its suitable for light weight rings.