Ferrules are used in process-reliable conductor assembly, wiring, and further processing. They offer many advantages in electrical engineering systems, both mechanical and electrical. The main task of the ferrule is to prevent the conductor from splicing and to protect the individual litz wires from mechanical effects, such as when connecting to screw terminal blocks. When spring-cage terminals are used, a firm connection between the copper conductor and the ferrule is essentially important. Alongside the appropriate ferrule pliers, the material quality of the sleeve is critical for an optimal and therefore reliable crimp connection.
The key advantages of ferrules
- Increased, long-term operational safety and contact reliability
- Time-saving further processing, particularly in the case of Push-in terminal blocks
- Reliable connection, even with repeated rewiring
- Reduction in cable breakages
- Easy cross-section detection
- Increased vibration resistance
- Permanently low contact resistances
- Individual litz wires are protected, particularly in the case of screw terminal blocks
- Consistent clamping in the case of screw connections
Standards for ferrules
In DIN 46228, the ferrule is defined as being between 0.5 and 50 mm². This standard has four parts:
- Part 1: Tubular end-sleeves without plastic sleeve
- Part 2: Crimp-type end-splices, with and without insulation grip
- Part 3: Conductor-embracing end-splices, without insulation grip
- Part 4: Tubular end-sleeves with plastic sleeve
Alongside the geometric dimensions of the sleeve, the material, the coloring according to the cross-section, and the test specifications are all part of the standard. In addition, there is the requirement that the ferrules accommodate Class 2, 5, and 6 conductors. The conductor cross-sections are defined through the electrical resistance values and not, as is the case for the ferrules, through the geometric dimensions. Greater variations in the cross-sections are therefore possible. Due to this fact, there is a certain discrepancy between the ferrule and the conductor. However, Phoenix Contact ferrule crimping tools are largely designed to compensate for this difference in capacity.
In addition to DIN, there is a French standard for the sleeves, NF C 63-023. With the exception of the coloring for some cross-sections, the NF standard is based on the DIN standard. The UL 486F and the Canadian C22.2 NO. 291-14 are new in the field of standardization for ferrules. These harmonized standards likewise are based on the DIN, but go further into detail on the test methodology and the specific requirements.
In UL 486F, the special sleeves such as the “TWIN” ferrules for a 2-conductor connection are also normatively defined for the first time. For certification in accordance with the UL and CSA standards mentioned above, comprehensive testing must be carried out by the respective organization. Not just the ferrules are tested and certified, but also the entire system consisting of the ferrule pliers and ferrule.
Trailblazer for international standards on quality, safety, and compatibility
As one of the first manufacturers, Phoenix Contact had ferrules – Made in Germany – combined with a selection of ferrule pliers certified in accordance with the UL 486F standard that went into force in 2016. Together with conformity with the DIN 46228‑1/‑4 standard, the ferrule pliers meet the market requirements in terms of quality, safety, and compatibility. Phoenix Contact therefore also has a system with global acceptance in its range for its export-oriented customers.