Pfisterer Sicon Mechanical Shearbolt Connectors � Sicon Screw Principle

By Chris Dodds on 28th May, 2015

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The Pfisterer Sicon Screw Principle - Product Installation

Terminals, connectors and cable lugs using screw technology have been advancing over the years and for several electrical engineering reasons.

Screw technology using mechanical shearbolts offers many technical and practical advantages that compression connections cannot provide.

Advantages include a large cross-section range, easy handling and installation requiring only a simple handheld tool. No hydraulic crimping tools and associated die sets required. No tool calibration required.

The Pfisterer Sicon connector consists of a screw, external threads and a pressure plate on the end of the screw.

Due to the stepless screw design, the build up of the contact force is not interrupted by steps or any notches in the screw. 

Pictured: Pfisterer Sicon Shear Off Screw Technology For Jointing, Terminating & Connecting Cables (Copper & Aluminium)

The screw is inserted using a standard hexagon wrench, the screw turns in the threaded sleeve until it touches the bottom of the sleeve. 

The threading link now rotates and the pressure plate at the end of the screw meets the conductor that is to be connected and the plate is then released from the bottom of the screw.

Each screw then continues to rotate and remains locked solidly on the conductor surface.

The Sicon screw continues to rotate until the shear torque is reached and the interplay of tension and contact force come into action.

Both forces are caused by the screw being turned in as they are equal and opposite forces according to the mechanical law “force equals opposing force”. 

Contact force is applied directly to the conductor and the tensile strength is in the opposite direction onto the threaded sleeve of the Sicon screw. Once optimum contact force has been achieved the shear torque is then reached.

The screw under tension then becomes streched axially within a predefined range of the screw sleeve until it shears off. 

SICON connectors are developed in such a way to ensure that the point of maximum tensile stress will always be located where the threaded sleeve emerges from the connected body. 

The Sicon screw will always break below the surface of the clamp body and does not leave any sharp edges or protrusions from the screw. The need for filing is therefore eliminated as was previously required which in turn reduces the risk of shock due to metal swarf. 

The Sicon screw shears very gently and without any sort or jerk or tension resulting in an easy installation.

Pictured: Pfisterer Sicon Shear Off Screw Installation

Advantages Of The Pfisterer Sicon Shear Off Bolt

• Up to 30% increased contact force on Al conductors compared with conventional type terminals
• No special tools required for installation reducing financial costs and saving time
• Full utilisation of the thread loading for any size of conductor
• When sheared off, the remains of the bolt stay on the tool to enable easy disposle 

Video: Sicon - The First Cable Connector System With Stepless Shear Bolts

Category:  HV Cable Jointing & Terminating

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