In addition to impacting data and network technology, the constant miniaturisation of whole devices increasingly affects drive technology being used. Here, the same principle applies as in data transmission: components must simultaneously become smaller, lighter and more powerful. However, the interfaces to the voltage supply have hitherto always presented a problem. The M12 in K-coding could be the solution to this.
The pursuit of miniaturisation and space savings extends to the gamut of components used in device construction. Housing, computer systems, network connectivity – everything is reduced in size while simultaneously ramping up in terms of power, speed or stability. Consequently, drive technology must also shrink. For electric drives with high power consumption, the 7/8" solution has been the standard to date. However, the 7/8" is bigger and is costly in terms of space. Some I/O boxes now have M12 sockets for data and signals. With M12 in K-coding (630 V, 16 A) the gap to L-coding (63 V, 16 A) has now been bridged and the limit for power density has shifted further upwards.
Supplying energy-hungry applications
In the area of circular connectors, which have been widely used internationally, power has so far been supplied via M12 A codings. But these quickly come up against their performance limits. For more energy-hungry applications, the 7/8" interface has been employed. Everything in between had to be covered by other interfaces. To close this gap in the area of metric circular connectors, new codes and standards needed to be added.
In the area of PNO (PROFIBUS user organisation), the L-coded M12 is available in the low-voltage range. With voltages of 63V at 16A, the L-coded M12 interface is the standard solution for I/O boxes in a Profinet environment. These are preferably used in the field of automobile production. But if drives with higher power consumption are intended to be supplied via a space-saving interface, the basic parameters of the L-coding are insufficient, and are given a boost by K-coding.
From a planning and technical point of view, with K-coding the last black spot on the energy supply map can now be removed. With 630V at 16A AC, some 7kW are available, which is more than enough power. For performance figures of this size in a compact M12 housing, special attention had to be paid to clearances and creepage distances as well as the adequate protection of users. This is solved by employing a PE contact directly attached to the housing which is designed in the mating face as a pre-leader, i.e. a pre-leading contact, in order to dissipate any voltages and to drain off a spark-over on the housing or between contacts in the event of uncertainty. The printed circuit board socket also had to be protected contact-side against voltage flashovers. For this purpose, all laterally sited hold-downs (THR) are mutually separated by an insulator star which must be factored into PCB design.
PushPull also offered
The cable side features K-coding as a crimp version. Locking is effected via the well-known and M12-typical screw connection as well as the new PushPull locking, which locks quickly and provides acoustic feedback when successfully locked. In addition to K-coding, which is at the forefront in terms of performance, the M12 codes S, M, T and L meet the more stringent requirements imposed on small interfaces with respect to power supply.
Connector technology terms
A solderless connection effected by crimping. With the aid of a crimping tool, the connection area of the contact part is deformed, thus producing a firm, gas-tight connection with the conductor. Crimping is suitable for single, multiple-wire and all the way to the finest wire conductors (strands). The crimp connection can be produced by hand crimping tools or on semi or fully-automatic crimping machines. The stripping of the cables and the crimping of the contact parts can be performed by machine in a single step (requirements and tests according to DIN EN 60352)
If the circuitry requires one or more contacts of a connector to make contact first (PE or GND) or disconnect last when pulled, extended contacts are used.
M12 connector codings
It’s one of the standards in automation: the M12 connector is a round connector with metric locking thread that is manufactured in multiple variants and codings for different applications. The M12 connector has now become the world's leading connection system for sensors, actuators, fieldbuses and network technology. Special coding ensures that the connector cannot be mated incorrectly. Pin counts range from 2 to 17 for A-coding. Shielded versions are used in 4- and 5-pin versions with A and B coding in fieldbuses and are standardised. For Ethernet up to 100 MBit, the 4-pin D-coded version and in the gigabit range the 8-pin X-coded version is used.