Wiring via WAGO terminals: connect and forget
Electrical engineering still remains, above all, the "science of contacts": with a 90% probability, any malfunction of the electronic unit is to blame for the lack of a contact in the right place or its presence in an unnecessary one. That is why experienced engineers choose terminals and connectors sometimes more carefully than other components.
The set of requirements for terminal connectors in different applications can vary greatly, but the reliability of the electrical connection will always come first.
Very often it is required to guarantee the guaranteed parameters of the connection for a long time, in conditions of exposure to vibrations or aggressive environments. There are important requirements, for example, to the strength of electrical insulation, fire safety, heat resistance. At first glance, a fairly simple component, terminal connectors represent the results of many years of work by specialists in various fields of science and technology.
What is the choice? If you put the quality and technical characteristics of the terminals in the first place, the choice becomes quite limited. All kinds of cheap solutions from the southeastern and Polish manufacturers of «early ripening» do not withstand any criticism in terms of reliability, stability and electrical parameters. The proven "monsters of terminal construction" remain, including the German company WAGO Kontakttechnick Gmbh. In addition to the famous German quality, the main feature of WAGO terminals is the absence of the traditional screw clamp.
The rest of the design features of this connector will be discussed further, but for now we will note the main advantages of this technology:
·Clamping force optimized in proportion to the cross-section without damaging the wire;
·Gas-tight connection at the point of contact;
High resistance to vibrations and shocks;
Multiple time savings during installation;
The independence of the quality of the contact from the qualification of the service personnel;
·No need for follow-up maintenance.
CAGE CLAMP: how it works
The principle of connecting wires in WAGO terminals is based on pressing the wire to the busbar with the help of a specially shaped spring. The spring is made of chrome-nickel (CrNi) steel, which allows a sufficiently high clamping force to be obtained. It automatically changes according to the cross section of the wire. In other words, in a terminal designed to work with wires with a cross-section of 0.2-16 mm2, you can clamp wires whose cross-section differs by an order of magnitude, without fear of damage to thin and underdevelopment or slippage of thick wires.
The principle of connecting wires based on the spring CAGE CLAMP The busbar is made of electrolytic copper. This material has optimal electrical conductivity, chemical resistance and resistance to corrosion cracking. The surface of the rubber is additionally protected with a lead-tin coating, which at the same time ensures the gas tightness of the specially shaped transitional contact.
The high specific surface pressure at the contact point in the CAGE CLAMP pushes the convex surface of the conductor into the soft lead-lead layer in the contact area. It also provides long-term corrosion protection. So what does the user lose by using WAGO terminals? Wire failure or pinching often occurs with screw terminals. Loosening until the contact disappears due to loosening of the screw clamp under the influence of vibration. The need to perform routine maintenance on the terminal connectors every six months. Technology for connecting a wire to a typical WAGO terminal based on the CAGE CLAMP spring
All you have to do to connect the wire is:
·Insert a screwdriver into the process hole to release the spring.
·Place the wire into the terminal.
·Take out the screwdriver, then the spring will automatically tighten the wire. Comparing these simple steps to connecting a wire to a traditional screw terminal, you can easily see where the savings in installation time come from and why maintenance personnel do not need special skills to work with WAGO terminals. It should be noted that the successful design of the cage clamp was preceded by 9 (!) Years of research and experimentation by WAGO engineers.
By the way, an automatic machine for the production of only one type of springs for cellular clamps costs about 500 thousand dollars. This is called "know-how" that cannot be stolen or quickly replicated.
As soon as the patent for this type of terminal expired a few years ago, they appeared from all their major manufacturers. However, they have a long way to go to reach the perfection and variety of WAGO terminals. Main types of WAGO terminals
The world of WAGO terminals is huge, suffice it to say that the complete product catalog of this company has about 700 pages. However, to qualitatively understand the main types and purpose of WAGO terminals, the volume of an article in the magazine is quite enough.
All WAGO terminals are divided into two large groups according to the type of spring used.
The first group — terminals based on a clamp with a flat spring... This type is optimal for single-core wires with a diameter of 0.5 to 4 mm2 and is most often used in telephony, building cables and building security systems. The second group — terminals based on the CAGE CLAMP clamp ... This type is ideal for both solid and stranded wires. In particular, it should be noted that when using the CAGE CLAMP, lugs / wire lugs are not a prerequisite for a high-quality connection. This year, WAGO has one more type of terminals — FIT-CLAMP, which is based on an included contact.To work with FIT-CLAMP, it is not necessary to remove the wire from insulation in advance, which further simplifies and speeds up installation work.
According to the method of installation in the equipment, WAGO terminals are divided into the following groups:
·For mounting on support rails type DIN 35
·For mounting on mounting panels
·For printed circuit board assembly A large number of auxiliary accessories are produced for all three groups, including marking tools, all kinds of contactors, test probes, wire cutting / stripping tool, etc.
For completeness, it is worth citing some of the maximum technical parameters of WAGO terminals:
·Guaranteed maximum permissible current 232 A
·Guaranteed maximum voltage 1000 V
·Maximum wire cross-section 95 mm2
·Permissible peak voltage 8 kV