Manufacturers of machines, modules and assemblies are rarely able to estimate which cables will actually be used by fitters in the respective country. So often the only option is to supply different cable glands, which on the one hand is associated with costs, but on the other hand does not guarantee that cables and cable entries will fit together and that a secure seal with strain relief can be achieved.

Thanks to the large, spherical sealing insert (blue), the 'blueglobe' provides a large-area, crush-free seal for the cable with protection ratings up to IP69K and high strain relief values.

© Plow

Cable glands that can be used as flexibly as possible are therefore in demand. One approach to this is the 'blueglobe' cable glands from Pflitsch, for example, which are available in sizes M8 to M85 with larger clamping ranges. These metric cable glands use a spherical sealing insert made of modified TPE plastic, which fits securely over a large area around the cable when the pressure screw is tightened. The result is a reliable seal with protection class IP68 or IP69K up to 30 bar. Thanks to the large-surface contact between the sealing insert and the cable sheath, the cable is not irreparably constricted, which ensures long-term operational safety. A grooved O-ring, which remains in position when the cable gland is screwed into the screw-in thread of the terminal box and is not crushed in an undefined manner, ensures reliable sealing towards the housing or terminal box.

This sealing principle with the large-area sealing insert enables the required large sealing areas. In practice, this means that cables with different outer diameters can be securely routed with just one cable gland. The standard size M20, for example, seals cables with diameters from 5 to 14 mm; with size M85, 65 to 77 mm are possible.

No slipping out of the cable

The large-area sealing of the cable gland also ensures significantly better strain relief than required by EN 62444 Class B. Even under strong vibrations or high dynamic forces, the machine builder can be sure that the cable will not slip out of the cable gland, which would result in leaks. Thanks to the soft crimp, the cable sheath is not irreparably constricted, as is often the case with conventional cable glands with lamellas. Cable breakage and leaks are ruled out from the outset.

The robust gland body made of nickel-plated brass and stainless steel with a metric thread in accordance with EN 60423 can also withstand higher mechanical loads. The temperature range of the cable gland from -40 to +130 °C corresponds to most industrial operating conditions. A polyamide plastic version is also available for the same operating temperature range.

The triangle spring

The 'blueglobe TRI' EMC cable gland is easy to install thanks to its triangle spring and contacts the cable shield 360° for maximum RF attenuation values for Cat. 7A applications.

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For applications where EMC safety is crucial, Pflitsch equips the cable gland with a triangle spring whose 360° contact ensures maximum attenuation values. This cable gland is therefore approved for applications with Cat. 7A requirements, where at least -60 dB attenuation is required up to 1000 MHz in accordance with DIN IEC 61156-5. The 'TRI' achieves -65 dB, and even in the frequency range up to 2.5 GHz it is typically at least -50 dB. Even higher EMC attenuation values are achieved by using a non-magnetic 'TRI' annular spring, as the non-magnetic version of the spring has no ferromagnetic influences on the shielding.

In the 'HP' version, the 'blueglobe' can withstand IP68 protection at 30 bar water pressure for one hour during leakage tests. Even water jets and high-pressure cleaners are no problem for this cable gland with IP69K. With silicone sealing inserts, operating temperatures between -55 and +180 °C are possible.

Sealing inserts for railroad applications in accordance with EN 45545-2 are also available. Pflitsch has modified the TPE material to meet this standard. In combination with gland bodies made of nickel-plated brass, the cable gland meets the HL3 requirements of the EU standard for unrestricted use in trains - whether on open tracks, in tunnels or in stations. Corresponding tests have also provided proof of an oxygen index >32 %, smoke gas density Ds maximum 300 and toxicity CIT maximum 1.5. This means that the cable gland achieves the prescribed fire resistance test 'room closure'. In the test, it remains tight for at least twice as long as required by the standard.

For cables from 10 to 25 mm

Another approach to making the cable connection flexible is a multi-inlet sealing insert: its three inlets can be easily removed with a screwdriver if required and thus adapted to the cable diameter used. This special TPE sealing insert increases the sealing range of the 'blueglobe' by a good 55%. In practice, this means that cables with a diameter of 6 to 20 mm can be safely routed through an M25 cable gland and sealed with protection class IP68 (15 bar). The M32 size is designed for cables from 10 to 25 mm thick. Despite the increased sealing range, the cable gland with multiple inlet achieves IP68 up to 15 bar and IP69. The strain relief values up to the highest achievable class B in accordance with EN 62444 are also achieved.

Author:
Walter Lutz works as a freelance technical journalist in Haiger.