mini CLIX: Explosion protected plug-in connector

Transcription

1 mini CLIX: Explosion protected plug-in connector Pull twist pull... it s as simple as that! by A. Fritsch Figure 1: mini CLIX: Explosion protected plug-in connector To date, explosion protection by intrinsic safety was the most practicable and used solution when carrying out installation, maintenance and repair work of measuring and control equipment in hazardous areas. But the question was: what was to be done with non-intrinsically safe components such as flameproof transmitters, explosion protected light fittings or increased safety bus connections? If it was not possible or not permitted to disconnect the system section, the only solution to date was probably the hot work approval, also referred to as Permit to work form. The tremendous effort required to obtain this hot work permission is both well-known and dreaded. This problem has now been elegantly solved with the new, innovative explosion protected mini CLIX Explosion Protected plug-in connector (Figure 1). This joint development of the two companies CEAG Sicherheitstechnik GmbH and R. STAHL Schaltgeräte GmbH allows the user, for the first time, to carry out installation and maintenance work on non-intrinsically safe circuits in hazardous areas during operation and without complex and expensive authorisation procedures. The explosion protected connector is approved for use in Zone 1 and 2 areas as well as both 21 and 22 (risk of explosion from gas and dust) and is marked II 2 G EEx de IIC T6 und II 2 D IP66 T52 C. 40

2 Ex-Magazine 2004 Safe galvanic isolation Self-cleaning multi contacts Flameproof enclosure Flameproof enclosure Terminal connection Increased safety Figure 2: Basis mode of operation mini CLIX Basic mode of operation The technical solution is just as simple as it is effective. Isolation of the circuits with mini CLIX is done on the basis of the two-stage principle (Figure 2). In the first stage, the circuits are first electrically isolated by pulling the connectors apart. Electrical isolation of plug and socket contact occurs within a small, flameproof enclosure inside the connector. A notch prevents immediate, complete separation of plug and socket. The potential electrical arc or contact spark, which may be produced as the result of separation of the circuits is still enclosed in the flameproof enclosure and is quenched safely. In the second stage, the plug and socket are separated mechanically. In order to do this, it is necessary for one of the two connectors to be turned approx. 30 degrees. A gentle click provides audible feedback that unlocking has occurred. Pull twist pull: it s quite simple! The plug-in connectors can be connected together following the reverse procedure. The connection is locked with a union nut in order to prevent it coming loose of its own accord and to guarantee the degree of protection IP 68. The cable connection area on mini CLIX are designed either with type of protection Increased safety e or, on the versions for direct connection to flameproof apparatus, with type of protection Flameproof enclosure d. Applications Availability of mini CLIX now opens up many applications, which have not been possible to date or which have been possible only with major effort and expense. Power supply connection of explosion protected instrumentation equipment frequently cannot be implemented with intrinsic safety owing to the high power ratings required and can be implemented most times only with type of protection Increased safety e, e.g. using an Ex e terminal chamber or an flameproof cable gland. This does not allow the wiring to be disconnected easily under live condition. With mini CLIX, it is now possible to design the connection as a plug-in connection as with intrinsically safe circuits. If, for instance, it is necessary to exchange a defective item of equipment, it can be disconnected from the mains quickly and easily and exchanged with a replacement device. Explosion protected luminaires with this plug-in connector can be installed or exchanged very easily and without the need for specially trained expert staff. This means that it is possible to prepare the entire power supply system for instance. The light fittings are then subsequently connected quickly, easily and at low cost. If mini CLIX is used on junction boxes, there are additional flexible options relating 41

3 mini CLIX: Explosion protected plug-in connector Figure 4: Ex d transmitter with mini CLIX Figure 3: Junction box with mini CLIX to power and signal distribution. Circuits can be connected and disconnected at any time during maintenance work without the need for special precautions or even a special Permit for hot work. This affords major advantages as early as the planning and installation phase owing to simpler and more manageable engineering. Also modification and extension of installation can easily be realised (Figure 3). One main application of mini CLIX is certainly in the sector of sensors and actuators. Thanks to mini CLIX, explosion protected transmitters or solenoid valves, which are not available or which are not available completely with type of protection Intrinsic safety i, can be serviced just as conveniently as the intrinsically safe units. With mini CLIX, replacing a defective or outdated device takes a matter of seconds. Disconnect the cable from the old unit, remove the unit, fit the new unit and reconnect the cable that s it! If we compare this with the effort previously required, the immense advantages of this Ex d connector quickly become apparent. Even modern field bus applications can benefit from mini CLIX. As long as a field bus such as Profibus PA or FF H1 is operated intrinsically safe, it is no problem exchanging or extending field devices. But what about non-intrinsically safe field buses such as those frequently used? These are typically designed as an Ex e bus with corresponding Ex e connections of the field devices to the bus. If field apparatus fails in this case and needs to be exchanged, this is where it becomes complicated. It is not possible to simply disconnect and exchange the individual apparatus. Rather, in the worstcase scenario, it is necessary to disconnect the entire field bus and, thus, all connected devices. This means that the entire section of the installation is out of operation! By contrast, field units featuring mini CLIX can be exchanged in operating state without further safety measures. This means that users can operate just as conveniently with I.S. field buses as they can with Ex i field buses in hazardous areas (Figure 5). Many other applications and uses in hazardous areas are conceivable. Thus, users use mini CLIX in conjunction with motors, as a servicing interface, on radiant heating systems or trace heating, for directly plugging small units on without cables and for connection of portable apparatus such as scales, pumps or portable lamps etc. The possibilities are simply unlimited. But using mini CLIX is worthwhile not only in hazardous areas. The very rugged design, the broad operating temperature range of 55 C to +75 C and the high degree of protection IP 68 also open up many applications in the industrial sector. Since no tools are required for connecting or disconnecting the connectors, this means that handling is easier than is the case of many available solutions in these sectors. Figure 5: Ex e fieldbus application 42

4 Ex-Magazine 2004 Advantages The above list of applications and the resultant advantages ultimately mean one thing: easier installation and maintenance and, thus, a saving on both time and money. The possible savings potential achieved by mini CLIX can be shown very simply with an example calculation. Let us take, for instance, an installation with 2000 process control loops with an operating period of 15 years. The average failure rate for repairs is approx. 5 %. The annual percentage of the devices to be serviced is 10 % with two maintenance intervals per year. The investment for mini CLIX is set off with 5 % interest per year. If we take as our basis the average hourly rates and working hours for Germany, we achieve a cost saving of around 40% and a time saving of around hours over the above service period. If the general framework is different, i.e. shorter service period, less process control loops or less failures etc., we do, of course, achieve other savings factors. However, in general, we can see from a wide variety of example calculations that this factor lies in the range between 30 and 60 %. We must also consider other savings achieved by far shorter rest times and, thus, lower production outage of machinery and system sections in the case of repairs or exchange of equipment. In the case of many production sequences, it makes a major difference whether the machine is stopped for one minute or for one hour. The typical sequence for exchanging a device, i.e. detect the faulty device, call a mechanic and electrician, grant a working permission, switch off the installation or the system section, disconnect the electrical connections, exchange the device, connect the electrical connections and put the system back into service, is in stark contrast to the far shorter process, if devices incorporate mini CLIX: detect the faulty device and exchange the device: that s it! Figure 6: Versions of mini CLIX But it is not only the end user who benefits from the advantages of the new plug-in connector system. Even for engineering consultants, it is worthwhile considering mini CLIX when planning. On one hand, diagrams and wiring documentation are simpler and clearer if plug-in connections are used instead of terminals and clamping units. On the other hand, there are advantages during installation and commissioning. Typically, up to 20 % of all connection points or measuring points still need to be changed during commissioning in practice. Using mini CLIX essentially shortens commissioning time. This means that the resultant cost savings lead directly to an improvement in profitability. If a manufacturer of field devices equips his transmitters and actuators etc. with mini CLIX ex works, this results in additional expense at first glance, i.e. the purchase price of these devices is higher. However, if we compare this additional price with the resultant added value, the whole matter already becomes more interesting. If we take the slight additional price resulting from a mini CLIX plug and the number of years in which the field device is operated and compare this relatively with the savings achieved during installation, maintenance, exchange and conversion work etc., we quickly see which field device is ultimately less costly and which field device will thus be accepted better on the market. After all, the purchase price is not the only thing which counts. Versions mini CLIX can be supplied with various designs, materials, connection systems and pin variants in order to cover the many available applications as well as possible (Figure 6). There is the mini CLIX connector designed as plug and coupler, for connection cables. This can also be used, for instance, to design extension cables for hazardous areas. 43

5 mini CLIX: Explosion protected plug-in connetor Table 1: Technical data Gas hazardous area Dust hazardous area Rated voltage Rated current Connecting capacity (crimp) Connecting capacity (spring clamp) Connecting leads, Ex d version Cable clands Degree of protection Ambient temperature Pin numbers (standard) Coding (standard versions) If the unit is installed in junction boxes, on field devices and luminaires and transportable systems, the device plug or flanged socket outlet version is used. If space conditions are at a premium, it is possible to install an angled adapter between plug or flanged socket outlet and field device to deflect the cable route through 90 degrees. Currently, either plastic or brass, nickelplated, are available as enclosure materials for the connectors and angled adapters. Stainless-steel versions are currently in preparation. Plug-in connectors made of different materials can be combined with each other easily. Thus, for instance, a plastic plug can be connected to a brass socket. The plastic used is a very impact-resistant polyamide which is resistant to most solvents so that this version is the best and least-cost solution for very many applications. The versions available in nickel-plated brass are ideal for applications requiring a very rugged plug connector. The brass plug or flanged socket are used in conjunction with flameproof field devices. This brass plug and the corresponding flanged socket are designed and approved as Ex de connectors for direct entries on flameproof apparatus and enclosures. Of course, however, they may also be used for applications on junction boxes type of protection Increased safety e etc. as a very rugged solution. For reasons relating to interference immunity, the metal version should always be used for high-frequency signal transmission, such as field bus applications. This metal version allows trouble-free, reliable signal transmission. On the basis of test results to date, it is possible to easily achieve transfer rates of up to 10 MBit/s. mini CLIX is currently being tested by an independent test laboratory for Industrial Ethernet applications for up to 100 MBit/s. mini CLIX is the first explosion protected connector system suitable for use with Ethernet. The plugs and sockets feature time-proven cage clamp terminals. Cables can be connected very quickly with a simple screwdriver and can be disconnected again, if required. Alternatively, connectors and couplers are also available with crimp terminals. Only the crimp terminal system is used on the device plugs and flanged socket outlets. This very compact, fast and reliable connection system has been integrated since the connecting cables in this case are normally terminated in the workshop and no longer need to be detached. This has also allowed the overall size of the mini CLIX device plugs and flange sockets to be minimised so that the additional space required for installation in field devices or junction boxes is only a little more than that required for glands. The insulation-displacement system could also be used in the future. However, it will be necessary to wait and see how this connection system fares in general on the market and how it is accepted by users in the future. II 2G EEx de IIC T6 II 2D IP66 T52 C 250 V AC / 60 V DC 10 A AC / 2,5 A DC 1 x 0, ,5 mm²; 1 x 2,5 mm² 1 x 0,5... 1,5 mm² 1 x 1,5 mm²; 1 x 2,5 mm² Ø mm; Ø mm IP 68 (2 m water gauge) C 2 P + PE, E P, 4 P + PE 02h (Busse); 04h (115 VAC); 06 h (240 VAC); 08h (24 VDC); 10h (240 VAC plus PE); 12h (24 VAC) Dimension: Plug / coupler ca. 96 x Ø 30 / ca. 95 x Ø 28 Dimension: Appliance inlet / Flanged socket ca. 60 x Ø 30 / ca. 63,5 x Ø 28 Option Locking device Technical data mini CLIX is prefabricated with various pin arrangements adapted to the diverse possible applications mentioned above (Table 1). The versions have differing numbers and arrangements of plug and socket contacts depending on the nominal voltage used, i.e. 24 V DC, 24 V AC, 120 V AC, 230 V AC or bus signals. In addition, the connectors are coded so as to prevent confusion. This clock position coding with 12 different times is based on the coding system of CEE plugs and sockets and can also be colour-coded for simple identification using the supplied rings. Using a very high-quality contact material means that no different versions of the contacts for various application are required. This means that a mini CLIX connector can be used both for low levels of 1V / 1mA, such as those 44

6 Ex-Magazine 2004 on bus systems, and also for high rated values of up to 250 V and 10 A AC. So, in this case, it is not necessary to keep different versions in stock for different applications. This has been made possible by the use of a special copper-beryllium alloy with nickel plating. Unlike on gold-plated contacts, this alloy is far less sensitive to burn-off when arcing. Whilst a gold-plated contact has no gold plating left after only a few connection cycles at 250 V and 10 A load and is thus unserviceable for use at lower levels, the contacts used with mini CLIX can still be used in this case for bus signals for instance. Owing to the additional nickel plating of the contacts, use in aggressive atmospheres and rough ambient conditions poses absolutely no problems. These high-quality contacts also feature self-cleaning pins and guarantee low insertion and removal forces, low contact resistances and low thermal loading and, thus, a long service life. In conjunction with the high IP 68 degree of protection in accordance with EN 60529, tested with two metres water gauge and with the broad ambient temperature range from 55 to +75 C, the mini CLIX connector is the ideal solution for all applications in industrial areas at risk of explosion from gas and dust and in Zones 1, 2 and 21, 22. interesting alternatives. Since mini CLIX, being a joint development of the R.STAHL and CEAG, is fully compatible with the corresponding exlink plug connector, the user has additional certainty in relation to availability and application diversity. The range of possible applications in the near future will even increase by supplementing the mini CLIX series of plugin connectors with a T-adapter for direct connection to bus-capable field devices and looping through the bus lines, a 6+1-pin version, stainless-steel enclosure materials and various, preassembled junction boxes for power or bus distributors. mini CLIX: pull twist pull it s as simple as that! Summary and outlook mini CLIX opens up entirely new possibilities in hazardous areas for the user, planner and manufacturer. The flexibility in the case of installations, the time saving during wiring and commissioning and the simple servicing and maintenance ensure cost savings and, thus, improved profitability. Many applications, which could not be implemented to date due to the unavailability of an appropriate product, are now conceivable. In the high-growth sector of field bus technology in particular, the user is no longer reliant on intrinsically safe solutions and now has 45