A well-designed electrical circuit is never complete or safe without electrical connectors. Any engineer designing a circuit. An electrical connector, also known as a PCB terminal block, is mounted on circuit boards to secure two or more wires together. Regardless of the appliances attached to the circuit, a PCB terminal block is a necessary component of any electrical circuit.
What is a Terminal Block, and Why is it Required?
In electrical circuits, wires are connected by stripping the rubber insulation and twisting the copper wires together. This method works fine when there are only two wires to connect. But there are many situations where simply connecting two wires like this can become risky. For example, what if there are many wires connected adjacent to each other? Or a situation where many output wires are connected to one single input wire? In these scenarios, the copper wires will be exposed, and the risk of starting a fire will become much higher. In addition to this, the risk of electrocution would also be increased manifold.
The insulating body of a terminal block consists of a metal strip called a terminal bar. On each side of the insulating body are clamped to hold the two wires that are to be connected. The current safely passes through the terminal bar. In this way, the two wires are securely held in place with no risk of disconnection. The barrier of the insulating body of the terminal separates adjacent wires that are closely connected hence minimizing the risk of electrocution and fires.
Terminal Block Design Types
PCB mount terminal block is the smallest size of terminal block that is used for printed circuit boards. It is multi-purpose and is utilized on any electronic device to ensure a safe connection of wires. It is available in three design configurations: single feed, dual-level, and multi-level modules.
This kind of terminal block has a screw terminal. To secure the wire, a ring or pad is attached to the wire, inserted on the screw, and the screw is tightened in the enclosure of the terminal block. Barrier strip terminals are utilized in situations where vibration can loosen the wires. These terminals have barriers of insulating material between multiple wires.
Feed Through Terminals
Feed-through terminals are used in wire-to-wire connections for two wires. Like all terminal types, they come in single, dual, and three, or multi-level modules. The terminal design consists of one input contact and one output contact. The two wires are inserted in separate enclosures. A conducting metal strip between the enclosures establishes a connection between the input and output wire. They are color-coded. Gray is the color for phase, and blue is the color for neutral wire connection.
Wire Securing Mechanisms Used in Terminal Blocks
This type of mechanism is the most popularly used in terminal blocks. The wire is pressed into contact with a conducting strip by tightening a screw. Screw-in terminals are built to fit a wide range of wire sizes. This type of mechanism is commonly used in household circuits where high voltage is involved. The downside of this mechanism is that the wire can become damaged if the screw is tightened too much. Also, this type of mechanism is time-consuming when multiple wires need securing, as it takes time to loosen and tighten the screw.
Spring clamp/Push-button mechanism
The spring clamp of the terminal is opened by pushing a screwdriver in or pressing a button. Once the clamp is open, the wire is inserted in the enclosed space, and the button is released, or the screwdriver is taken out to close the clamp and secure the wire against the conductor. This connection method is easier than screw-in, and the wire is simply secured by pushing a button or removing the screwdriver.
This mechanism resembles a push-button method but does not require any button to be pushed or a screwdriver to be inserted to open the clamp. The wire is simply connected by pushing it into the insertion point. The conducting strip is held by a pressure spring and simply opens automatically once the wire is pushed in. Once the wire is in, the pressure spring keeps the clamp tight against the wire. This is the quickest mechanism to connect the wire as involves no screws or buttons. Moreover, it also prevents overtightening of the wire.
Things to Keep in Mind for Choosing the Terminal Block Type
PCB terminal blocks are available in a variety of current ratings. A high current passing through a terminal block can damage it through overheating. Therefore, always confirm the current rating of the terminal block.
A voltage surge can damage the insulating material and also cause it to conduct electricity between the adjacent wires. This results in short-circuiting and can damage electrical appliances. The voltage rating of the terminal block should be higher than the maximum system voltage.
To ensure a secure fit in the protector block, the wire's thickness should not be excessive, which could cause the wire to be loosely secured. Additionally, the wire type should be taken into consideration. Single-core wires are appropriate for push-button and push-in terminal blocks, while for multi-core wires, screw-type blocks may be preferable.
Amount of Poles
The quantity of individual circuits in a system is defined as the pole mount. A system can consist of one pole or be more than 48. You should accurately know how many circuits are a part of your circuit design.