Terminal Blocks
Terminal blocks allow for a convenient and safe way to connect two or more wires within a control cabinet. They serve as our connection points, where easy initiation and termination of electrical contact can be made. When wired properly, a terminal block setup can be easier to comprehend than traditional wiring schemes. Because you wire a terminal block differently, you can reduce the risk of short circuits and other wiring faults.
There are many different types and designs of terminal blocks, and each one is appropriate for certain applications. Here are a few of the more typical configurations: feed-through, barrier, and modular. Feed-through terminal blocks are often used for connecting signal and control wires to equipment. These blocks have holes that the wires poke through, with brass screws (screw connection technology) on either side that clamp the wire in place. Barrier terminal blocks are for power and high-current connections and come in two varieties, single and double row. Modular terminal blocks mostly have diagonal "screw-and-rounds-together" wire connections when they're put together in the field.
Fuse terminal blocks incorporate fuse holders into the standard terminal block design. This allows the overcurrent protection to take place at the point of connection, within the terminal block itself. Fuse terminals are used in circuit protection applications to protect circuits and equipment from excessive currents and short circuits. They also allow easy fuse replacement and have visual indicators to show when a fuse has "blown" (i.e., opened or disconnected), both features that enable circuits to be brought back into service with minimal downtime.
More Information about Terminal Blocks
There are three common terminal block types: feed-through, PCB mount and barrier strip.
Feed-through terminal blocks contain one input and one output contact where two separate wires are inserted into opposite sides of the housing to connect the two wires together.
PCB mount terminal blocks are made for mounting on printed circuit boards (PCBs). Some types clamp bare wires into the housing, which is then soldered to a PCB, while others can be plugged into a pin strip that is mounted to the board.
Barrier strip terminal blocks feature a screw down terminal that attaches a bare wire or a ring or spade terminated wire. The wire is placed onto the screw and tightened into the housing for a secure connection. Barrier strips often have more than one termination point for multiple wires and provide small barriers between the individual terminals.
Three common wire-securing methods for terminal blocks are: screw-type, push-fit and insulation displacement connector (IDC).
Screw-type terminal blocks utilize a screw that tightens a clamp to secure the wire into place.
Push-fit terminal blocks use spring-loaded levers that allow wires to enter the terminal block in one direction, but do not allow them to be pulled back out.
Insulation displacement connectors (IDC) allow the unstripped wire to be inserted into the terminal block, which then uses two metal blades to cut through the insulation, making the proper contact with the conductor.
FAQs
What terminal block connection technologies utilize bolt connection?
Terminal block connection technologies that utilize bolt connections include stud terminals and ring lug terminals, where wires are secured to the terminal block using bolts and nuts for a reliable and robust connection.
Terminal Blocks: The Top 5 Things You Must Know
Is there a plan in place?
Make sure to have a proper plan in place for a specific application. With such a wide variety of terminal blocks available, it is important to use the correct types for various circuits. If the wrong types of terminal blocks are used, it could cause many issues, including possibly being very dangerous.
Is a disconnect necessary?
The most basic types of terminal blocks, simply act as a junction point. This allows current to pass through with nothing to stop it. However, if there is a need to stop current from flowing, some kind of disconnect will be required. There are a variety of different types of terminal blocks that have manual disconnects that can be used for this very purpose.
What about protection?
In many cases, devices connected to terminal blocks need protection. Terminal blocks that have a place for a fuses to be connected would be the ideal choice.
Is space limited?
In situations where there is very little room to accommodate the amount of IO that is need for a specific scenario, multi-level terminal blocks can wire multiple points or circuits in much less space than using single level terminal blocks.
Is grounding necessary?
When doing any kind of electrical wiring, proper grounding is essential to make sure all components in that circuit function properly. There are several different styles of grounding terminal blocks to meet different scenarios.