Interconnection
Figure 1: The M12 design is widely used in the field level of automation, for example for sensor-actuator cabling; field-wireable male and female connectors provide flexibility during installation. Photo: binder
EN 60529 or ISO 20653 often results in the misleading assumption a high number in the IP code necessarily means better protection. It is therefore important to know that the first digit of the code refers to the ingress of solid particles, such as dust, while the second digit indicates protection against humidity and water. Thus, a product rated IP64 cannot be considered ‘better protected‘ in general compared to an IP55 product. The former may be more exposed to particles, i.e. it is dustproof. However, it can only withstand splashing water, while the second can be exposed to jet water from any angle. The two digits for particles and humidity/ water can be followed by code letters in the third and fourth positions to indicate the protection degree more precisely. For example, a K (as in IP69K) stands for road vehicle equipment; a B for access to hazardous active parts with a finger.
It is important to emphasize that the IP protection degree refers to the protection of equipment and its components only. It does not make any statement about the protection of persons who interact with this equipment. Measures for the safety of users are defined in the so-called protection class, which is not the subject of this article.
Waterproof in an industrial context In addition to electrical parameters such as
rated current and voltage, surge voltage or contact resistance, installation-relevant parameters such as integration density and degree of miniaturization – and consequently the design of a connector – are general selection criteria. Beyond this, however, it is necessary to evaluate the special features of the respective application environment. Is the interface exposed to mechanical loads such as shocks or vibrations? Are precautions to be taken against the influences of adjacent high- frequency electronic assemblies, against the risk of fire or explosion? Or does a connection that has to be mated and unmated frequently require special design considerations in order to endure many mating cycles? The answers to these and similar questions lead the user to product features such as locking system, electromagnetic shielding and contact materials, which necessarily influence the purchase decision.
The fact that connectors must – in an initially undefined manner – withstand the ingress of particles and humidity or liquids is a standard requirement in the industry. But as explained above, the necessary protection degree depends on the details of the application. As these range from interfaces in measurement and control in factory automation, through the Food & Beverage industry, to clinical use of medical instrumentation, the requirements
Figure 3: Miniaturized and waterproof to IP67: The 620 and 720 series with O-ring on the female side and seal in the clamping area. Photo: binder
Figure 2: Not Connected Closed – thanks to a spring-loaded plastic cover, the NCC connectors of the 770 series are protected from particles and splash water even when unplugged. Photo: binder
for ‘waterproof’ connectors can vary considerably. Especially in the latter two areas, the products are exposed to a particular humidity load resulting from the cleaning and sterilization processes required here.
Product examples featuring IP67 and IP68/69K
All M12 connectors from binder are resistant to moisture and water in accordance with IP67 standards, and many are also resistant to IP68/69K. Corrosion- resistant variants are equipped with stainless-steel or plastic threaded rings (Figure 1). While IP67 ensures application safety in occasional humidity – without higher requirements – the more resistant products, depending on the protection degree and material, can also withstand weather conditions in outdoor use as well as immersion in greater depths, high-pressure water jets and aggressive cleaning agents.
The IP67 portfolio also includes M12 plugs and sockets that can be assembled. Connection technology with IP67 protection, such as the binder NCC (Not Connected Closed) series 770 (Figure 2), are recommended, for example, for use in handheld terminals, medical equipment and LED lighting assemblies. Equipped with a bayonet lock and designed for more than 5,000 mating cycles, these products are
characterized by a special design feature. A spring-loaded plastic cover inside their housing encloses the contacts – when unmated – so that they are safe from accidental touch. They are thus protected against particles and splash water, and are also protected against mechanical impact from the outside.
The so-called subminiature and miniature series 620 and 720 – when mated – also meet the IP67 criteria (Figure 3). For this purpose, they are equipped with an O-ring on the female end as well as with a seal in the clamping area. Despite their sensitive snap-in elements, the connectors withstand more than 1,000 mating cycles. They are also suitable for medical equipment; other possible applications include metrology equipment, industrial lighting or the seat heaters in sports stadiums.
All molded cable connectors of the 763 series (Figure 4) featuring signal and sensor cables as well as threaded rings made of media-resistant and temperature-resistant plastic are waterproof to protection degree IP68 when mated. Protection to IP68/IP69K is achieved by the outdoor connectors with bayonet quick locking of the HEC series (Figure 5). Application examples include tunnel lighting for very humid environments, underwater metering probes and supply lines for submersible pumps. HEC connectors are also widely used in agricultural
Figure 4: IP68-compliant 763-series cable connectors in different versions. Photo: binder
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Components in Electronics
March 2023 31
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