Medium Voltage Insulators

Post-insulators for Medium Voltage Applications by Radiant Enterprises

Radiant Enterprises manufactures post-insulators for medium voltage applications.

Radiant offers standard and custom epoxy insulators for medium-voltage interior and outdoor applications.

In addition to our ordinary or standard insulators, we specialise in customised epoxy insulators for air-insulated switchgear (AIS) and gas-insulated switchgear (GIS).

Radiant provides a variety of testing equipment, including partial discharge or electric serial tests, gas-leakage testing, x-ray testing, and customer-specific individual insulator inspections, to assist you in the development of your epoxy insulator, mv bushing, and customised epoxy housing for mv switchgear from the beginning.


Custom-made high current bushing and bushing terminals with coated copper for special application in railway technology.

Medium Voltage Support Insulator

Standard outdoor and indoor epoxy support insulators for medium-voltage (12kV to 24kV).

Insulating Base

Customized strong insulating base for lightning arrestors and surge arrestors.

Breaker Pull Road

Customized epoxy resin casted product for switchgears

Surge Counter Bushing and DisConnectors

The six primary types of insulators commonly employed in low or medium voltage are highlighted in the following sections.

  • 1. Pin Insulators
  • 2. Shackle Insulators
  • 3. Stay or Guy Insulators
  • 4. Reel Insulators
  • 5. Egg-Type Insulators
  • 6. Aerial Fuse

1. Pin Insulators:

A 'pin insulator' is an insulator that is attached to a pin or bolt. The pin is threaded on both ends. The thread at one end of the pin is tightly connected to the thread within the insulator, while the thread at the other end is secured with nuts to a bracket or cross-arm.

The insulator has grooves on the top as well as on the sides. This allows the line conductor to be tightly bound to the insulator. Pin insulators come in a variety of configurations depending on the line's supply voltage.

The wire is drawn over pin insulators fastened to the cross-arms that are attached to intermediate poles in between the starting pole and the end-pole in an overhead line. A conductor is fastened to the top groove of the insulator if the line is relatively straight.

The conductor is fastened to the groove at the neck of the insulators if the line deviates from the straight course at an angle of not more than 15° to 20°. A pin insulator is used on overhead wires to install horn-gap lightning arrestors, among other things, in addition to keeping the conductor fixed to itself.

2. Shackle Insulators:

Pin and shackle insulators are used for low and medium voltage overhead wires. However, in comparison to pin insulators, the use of shackle insulators has expanded dramatically in our country. The fundamental reason for this is that today's medium voltage overhead lines do not have conductors oriented horizontally.

The conductors are almost often put in a vertical orientation on one side of the pole at this time. This makes drawing line conductors on pin insulators attached to cross-arms problematic. Shackle insulators are usually clamped to intermediate poles with D-iron clamps in this configuration.

The shackle insulators are fastened to cross-arms with the help of shackle straps at terminal poles, i.e. poles where the line begins or ends, and poles where the line deviates from the straight route farming at a large angle. There is a groove in the middle of a shackle insulator into which a line conductor is fastened.

3. Stay or Guy Insulators:

Stay-wires are permanently attached to specific roles in an overhead line system. There are two components to this wire. The upper part is clamped to a pole, while the lower part is attached to a stay-rod that is grouted in an earth trench. A stay-insulator or guy-insulator is installed at the junction of the two pieces to maintain the upper part insulated from the lower part. At least three meters above ground level, this intersection should be maintained.

Stay-insulator is a porcelain object with a unique shape. It has two holes that are perpendicular to each other. One hole is used to pass the lower half of the stay-wire. With the help of a stay-rod, the other end of this wire is secured to the ground. The upper section of the stay-wire is attached to the pole after passing through the other hole.

The three most common colours of stay-insulators on the market are green, brown, and white. This sort of insulator is extremely robust and long-lasting, with the added benefit of the stay-wires remaining attached even when it wears out.

4. Reel Insulators:

Reel insulators are used to tie up phase-type-safety devices' when overhead wires are drawn in a vertical orientation. This insulator has a groove running through it and a hole in the middle. The earth wire is at the top and the neutral wire is at the bottom in the vertical configuration.

The neutral wire is still wrapped up on the upper half of the groove in the middle of the reel insulator. This configuration eliminates the risk of a short circuit between the earth and neutral wires.

5. Egg-Type Insulators:

If a neutral wire is used on one side and an earth wire on the other, an arrangement must be made to keep the neutral wire insulated from the earth wire when binding cross lacings (tiny pieces of wire) of cradle guard. Egg type insulators with lacings on the side where the neutral wire is drawn are commonly used for this purpose.

The insulator should be as close to the neutral wire as practicable. The reason for this is that if the live lines are snapped, they will come into direct contact with the earth wire, whereas the egg insulator will keep the neutral wire insulated from the earth wire.

6. Aerial Fuse:

A specific type of fuse-holder constructed of porcelain is used to fix a fuse wire in an overhead line. There are two terminal screws on each of the fuse-two holder's sides. The line wire is attached to the screws on one side by nuts, while the fuse wire is connected to the screws on the other side by nuts with a specially designed head. A service connection is taken from a live line or phase wire through this fuse when a house-service connection is drawn from an overhead line at low or medium voltage.

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