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Screwless terminals save time and reduce damage to conductors

25 March 2010

Screwless or 'spring' terminal blocks from distributor Switchtec offer a variety of benefits to manufacturers, end users and maintenance teams.  The terminal blocks save time and bring enhance reliability while reducing costs.

Made by Euroclamp, the screwless terminal blocks use a spring clamp to grip the wire whereas traditional terminal blocks have to be tightened using a screw by the installer. The traditional screw terminal has been the mainstay of terminal blocks for many years - but there are draw backs associated with screw clamp technology.

The amount of pressure or 'tightness' of the screw clamping the wire depends entirely on the installer, and if not tightened enough could result in loose wires.  Similarly overtightened screws can wholly or partially sever conductors rendering them completely open circuit or liable to intermittent failure in the future as a result of mechanical vibration or oxidisation.

Screwless terminals provide a secure and uniform pressure connection across each terminal.  Obviously they are also quicker to use, as no tightening of screws is required. Screwless terminals can take less space on the PCB, enabling smaller boards and more compact products and equipments. They are also ideal for applications where vibration may be present.  Screw terminals can be susceptible to vibration that can result in loosening of the connection, as clamping screws will gradually rotate in the direction of least resistance i.e. open. Screwless terminals do not suffer in the same way.

There are three types of operating mechanisms, the so-called push button, lever, and push wire types. The push button and lever types operate in a similar manner, i.e. depressing the button or lever opens the clamp, then after insertion of the wire, releasing pressure on the button closes the clamp, firmly gripping the wire conductor. The push wire connection requires the use of a tool or screwdriver that is inserted into the terminal block to open the clamp, then removal of the tool allows the clamp to close.

The Euroclamp screwless plug range from Switchtec is available from 2 to 24 way in 3.5, 3.81, 5, and 5.08mm pitches with ratings of up to 10A, 300VAC. They are available in vertical and horizontal connection and all utilise the push button clamp connector.

The screwless terminal block range is available from single way connectors up to 24 way in pre moulded options, although most of the range is modular and enables the terminal block to be as many ways as is needed. The terminal blocks are available in 2.5, 2.54, 3.5, 5, 5.08, 7.5, and 7.62mm pitches with ratings up to 16A, 450VAC. They are available in horizontal, vertical and angled profiles and are available with all three types of clamp connector.

As a measure of its dedication, in 2009 Euroclamp completed a new factory at its headquarters near Isernia, Italy specifically for the production of the screwless terminal block range, thus underlining the importance Euroclamp places on this new range.  Euroclamp used its extensive knowledge in the production of screw terminal blocks to develop the screwless range.

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