In this video, we're going to introduce you to the Terminal Block
which is an important component in any industrial setting.
A terminal block is a component with an insulated frame
that has the sole purpose of securing two or more wires together.
Well…. you might ask,
“If you want to connect wires,
why not just solder them together?
Or twist them together and wrap them with electrical tape?”
Using terminal blocks is a much better solution for connecting wires.
Terminal blocks provide more flexibility.
For example, when using terminal blocks,
wiring modifications are easy
because wires can be removed or added quickly.
Terminal Block wiring is neat and orderly
allowing for quick identification
making modification and troubleshooting easier.
We'll show you more good reasons to use terminal blocks later in this video.
Terminal blocks are classified based on characteristics such as structure,
device type, and termination options.
Let’s explore some of the classifications and characteristics of terminal blocks
typically encountered in industry today.
There are a variety of methods used to connect the wires inside the terminal block.
Let's have a look at some of the more popular ones.
Probably the most commonly used method for connection
is the “Screw-in” terminal block.
“Screw-in” terminal blocks are those that use screws
as the method for holding the wires.
Be careful! Over tightening the screws can damage the wires
and result in poor or potentially dangerous connections.
The “Barrier” terminal block is very similar to a “screw-in” terminal block
as they use screws to clamp the wires.
Depending on the application and environment,
the “Barrier” terminal strip may have a small lid to protect the wiring.
Like the “screw-in” terminal block,
it's important to strip the wire to the correct length
or the screw clamp might not make contact with the wire itself.
Another common method for wire connection
is the “Spring-loaded" terminal block.
A connection is made by simply inserting the wires.
Most of these terminal blocks
require the wire to be attached to a ferrule before it is inserted.
The ferrule or wire
is attached and released by inserting a spring release device.
Some vendors have a unique spring release device
while others require a small screwdriver.
The “Push-fit” or “push-in” terminal block is becoming very popular.
Much like the “Spring-loaded” terminal block,
the “push-fit” often requires the wire to be covered by a ferrule.
Several vendors make “push-fit” terminal blocks.
A connection is made by simply inserting the wires.
The big difference between the “spring-loaded”
and the “push-fit” terminal block
is the method of wire release.
“Push-fit” terminal blocks
have the release device mounted right next to the wire insertion point.
Another terminal block that was first used in the “Telco” industry
is the “Insulation Displacement Connector” or “IDC”.
The wire insulation does not need to be removed before insertion.
Two sharp blades inside the terminal block will slice through the insulation
and make contact with the wire.
When first introduced,
this type of terminal block was more suited for solid wire than stranded
although there are vendors now making IDC’s for both.
As the name suggests,
a “Pluggable” terminal block
has a plug outlet to allow connection to a socket.
The wire is inserted and clamped with a screw.
Connection to the wire is made via a plug and socket configuration.
This terminal block is used in situations where a quick disconnect is required.
On “Tab Connector” terminal blocks
a wire attached to a connector is pushed onto a tab.
The wire can be “crimp-connected” or “soldered”
depending upon the type of connector.
“Tab Connector” terminal blocks are also available
where one side of the terminal block is a tab connection
and the other side of the terminal block is a screw clamp connection.
Okay…now that we have investigated some of the more common connection methods,
let’s have a look at some of the different terminal block types.
At first glance, a “Ground” terminal block
looks like a typical terminal block.
Instead of connecting wires,
the “Ground” terminal block connects the incoming wire to “Ground”.
The wire is terminated by the panel or the “DIN Rail”
or wherever the block is mounted…
We will talk more about DIN rails later.
“Fused Connection” terminal blocks have a fuse inserted in series
between the wire-in and the wire-out
eliminating the need for external overcurrent protection.
To aid in troubleshooting,
many vendors have included a built-in “Fuse Failure LED” circuit
to provide a visual indication of the fuse condition.
A “Thermocouple” block is designed to accept thermocouple lead connections.
Thermocouples cannot be connected to typical terminal blocks.
As soon as the thermocouple wire makes contact
with the conducting material inside the terminal block
an unwanted junction occurs.
Any dissimilar metals joined together will create a new junction,
and consequently an unwanted voltage.
To avoid creating a new junction,
some thermocouple connectors clamp the thermocouple leads together
on both sides of the block.
Some vendors have developed “Thermocouple” blocks
with the internal metal connection strip made of the same metal
as the thermocouple wire itself.
Quite often, space inside a cabinet or an electrical panel is limited.
To save space,
individual terminal blocks can be connected to form groups or clusters
and are generally structured in multi-level configurations.
Each configuration has a different number of “layers” or levels.
For example, a “Triple level” terminal block has three layers.
In this schematic example,
the terminal blocks have 3 levels.
We are only showing 4 of the several terminal blocks
that create what is labeled as “TB4101”.
The levels are designated as “B” for bottom or “Layer 1”,
“M” for middle or “Layer 2”, and “T” for top or “Layer 3”.
Interpreting this schematic is not that difficult
once you know that the terminal blocks are multi-level.
The label “TB4101-2M”
means that the wire is connected to “TB4101”, terminal block 2, layer 2.
Terminal blocks are mounted in a variety of ways
but by far the most common is by attachment to a “DIN rail”.
A “DIN rail” is a metal rail of a standard size
universally used for mounting devices and components
inside electrical panels and equipment racks.
If you want to learn more about “Thermocouples” and “Junction Voltages”,
you might want to review our video called “What is a Temperature Sensor?”
You can find the link to this video in the description.
Ok…let's review what we’ve covered in this video:
A terminal block is a component with an insulated frame
that has the sole purpose of securing two or more wires together.
Terminal blocks are classified based on characteristics
such as structure, device type, and termination options.
Terminal Block Connection methods include
Screw-in,
Barrier,
Push-fit,
Pluggable,
Insulation displacement,
Spring loaded,
and Tab
Terminal Block Types include Ground,
Thermocouple,
and Fused
The most common terminal block mounting method
is by attachment to a “DIN rail”.
If you want to shop for terminal blocks
you can check out the RealPars marketplace.
We'll add a link to the video description.
Using the RealPars marketplace,
you can order different types of high quality terminal blocks with great pricing.
Also, if you have any questions regarding which type of terminal blocks to order
or about terminal blocks in general,
you can reach out to our experienced technical support.