Milton Keynes, UK, September 9th, 2017: Cyntech Components, a specialist supplier of Hammond Electronics products, Russell Irvine writes;
At the macro level, the Internet of Things (IoT) is rapidly developing as the convergence of multiple technologies advances at increasing speed. In the industrial environment, increasingly ubiquitous wireless communication, real-time analytics, machine learning, sensors and other physical devices are all forming part of embedded systems with electronics, software, sensors, actuators and network connectivity which enable them to collect and exchange data. IoT offers advanced connectivity of devices, systems and services that goes beyond machine-to-machine (M2M) communications and covers a variety of protocols, domains, and applications, potentially resulting in improved efficiency, accuracy and economic benefit in addition to reducing the level of human intervention required. Industry 4.0 about which much is heard these days, is the name given to the current trend of automation and data exchange in manufacturing technologies, where inter alia, IoT is obviously a key enabling technology.
At the other end of the spectrum, the micro level, the IoT requires rapidly increasing deployment of distributed electronics, particularly in manufacturing facilities, where intelligent connected equipment is replacing dumb sensors. These mini-systems will often have embedded IP capability, Wi-Fi and Bluetooth connectivity, processing and communicating information from their attached sensors and controls rather than the raw signals going back to a central control room. From the enclosure manufacturer’s point of view, providing suitable housings for these often physically small systems must provide physical protection for the housed equipment and in particular protect against the ingress of solid objects and water. The relevant international standard is EN 60529, which defines ratings written as IPxx, where the first digit defines the protection against solid objects and the second the protection against water ingress.
EN 60529 Protection Classes for protection against contact and solid bodies
|First figure||Scope of protection|
|1||Protection against contact by the hand with active or internal moving parts. Protection against penetration of solid bodies with a diameter greater than 50 mm.|
|2||Protection against contact by the fingers with active or internal moving parts. Protection against penetration of solid objects with a diameter greater than 12mm.|
|3||Protection against contact with active or internal moving parts with tools, wires, etc. of a thickness greater than 2.5 mm. Protection against penetration of solid objects with a diameter greater than 2.5 mm.|
|4||Protection against contact with active or internal moving parts with tools, and wires greater than 1 mm.|
|5||Complete protection against contact with live or internal moving parts and protection against harmful dust accumulation. The penetration of dust is not completely prevented, but it may not penetrate in such quantities that the operation of the equipment is affected.|
|6||Complete protection against contract with live or internal moving parts. Total protection against the ingress of dust.|
Protection classes for water protection
|Second figure||Scope of protection|
|1||Protected against vertically falling drops of water|
|2||Protected against direct sprays of water from up to 15 degrees from the vertical|
|3||Protected against direct sprays of water from up to 60 degrees from the vertical|
|4||Protected against water sprayed from all directions: limited ingress that does not affect the equipment operation is permitted|
|5||Protected against low pressure jets of water from all directions: limited ingress that does not affect the equipment operation is permitted|
|6||Protected against strong jets of water from all directions: limited ingress that does not affect the equipment operation is permitted|
|7||Protected against immersion between 150mm and 1m for up to 30 minutes: limited ingress that does not affect the equipment operation is permitted|
|8||Protected against long periods of immersion under pressure: limited ingress that does not affect the equipment operation is permitted|
An enclosure for general purpose use would typically be rated IP54, whereas one for use in hostile environments would need to perform to a minimum level of IP65, but nowadays IP67 is becoming the de facto minimum requirement. In general, enclosure manufacturers use two main techniques to achieve the designed protection level. Satisfactory IP54 sealing is readily achieved by using a tongue and groove construction to the joint between the body of the enclosure and a removable panel or lid. No gaskets are used; the seal is achieved through the combination of a recess in the base section that mates to the corresponding mirror profile in the lid when the lid is screwed down.
To achieve higher levels of sealing in metal, plastic and extruded small enclosures will require a gasket between the two mating halves. Normally a separate, preformed moulded gasket is sandwiched between the two mating surfaces. A metal enclosure can be painted if required without having to mask the gasket area; the gasket can be easily replaced if it is damaged.
The majority of enclosure manufacturers will quote the IP rating of their products as part of the specification, enabling the project engineer to select the most appropriate packaging for the intended application – inadvertently to end up with an ideal enclosure that also happens to be rated at IP67 for equipment that will only ever be used in the office environment could be somewhat over the top. As always, the best advice is to talk to the specialist enclosure supplier as early in the design cycle as practical; timely advice on the selection of the enclosure frequently saves a lot of development time and money.