TERMINAL BLOCKS-PART 4 (CLAMPING TECHNOLOGIES)

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In the previous post we were talking about the metallic parts of the terminal blocks out of which one of them is the current bar. Up till now we have seen the insulating part and the conducting part of the terminal bock,but we forgot to think about one thing that how will we hold the wire in place (definitely not soldering !).

So how?!.

The wires need to be in complete contact with the current bar for the maximum output,now in order to do that we need something to hold the end tightly. Now this is where the third metallic part of the terminal block comes into play.It is called the conductor clamp.

Let's break this word up into two parts first conductor means that it is made up of conducting metal and the "clamp" means to hold something together tightly.So by this word only you must have understood that this is a very important part of a terminal block.Mind you clamp is not a name its a principle.They come in different shapes and sizes.Clamping is also known as termination so terminal blocks may use one of several different methods to achieve wire connection.

Let me list out some of the most used and basic clamping technologies:

1. Screw clamp-Steel.
2. Screw clamp-copper alloy.
3. Screw clamp Spring loaded.
4. Spring clamp.
5. Stud and nut clamping for cable lugs

Brief description:

• Screw clamps use a screw to tighten the wire and make an electrical connection and are the classic, industry standard termination method. This type can accommodate a very wide range of wire sizes and provides a reliable connection. 
• Spring clamps use the force of a spring to retain wire clamping. They represent a newer alternative to screw clamps and are particularly useful in applications using small wire diameters and limited working  space.
• Insulation displacement connections (IDC) push the wire between two sharp pieces of metal, allowing a connection to be made without exposing any bare wire.
• Tab connections are designed to be inserted and removed rapidly without the need for soldering. They are also known as spade or blade terminals.

Detailed Explanation:

The dimension of these current carrying parts varies in regard to the amperage/wire size and the construction of the block itself. Depending upon terminal block layout, wires can be clamped in position using screws, a combination of screws and pressure plates, wire cages or spring clamps.

 A screw is the easiest method of connection: A screw is utilized to secure the wire against the current bar. With screws and a pressure plate, the wire is constrained with a metallic plate, which fastens the wire when the screw is secured. The drawback of this method is just that whenever these terminals are subject to the vibration , there is a possibility of disconnection of wires.

Screw clamp technology

Next comes the screw clamp spring loaded clamping technology,now the only change in this is the addition of the spring under the screw clamp.This technology comes after the normal screw clamp terminals had problems working in places where vibration is more prevalent like in cement ,oil and gas etc.

Screw clamp spring loaded technology

With a wire cage, when the screw is tightened, a cage pulls upward and squeezes the conductor against the current bar. The large contact area provides exceptional contact properties. Because the screw does not have immediate contact with the conductor, wire damage is prevented.Even thin stranded wire can be connected without the use of additional Ferrules or wire pins.

 Spring clamps require a tool to open. The clamp encloses the wire to provide dynamic clamping. This extra holding action endures vibration.Spring clamps are the best of the lot.Still some people are still using the other technologies cause they cost you a wee bit more.

There are many companies that make terminal blocks such as Phoenix contact,Connectwell,Weidmuller,Mouser,DigiKey,Allen Bradley,Schneider Electric,Altechcorp etc

So that's it for this article ,in the next one we will cover the categorization of the terminal blocks.

Till next time!!

Bye!