kubler articles

Slip Rings with Integrated Sensors

Kubler 12/1/2017

Slip Rings with Integrated SensorsModern food industry production facilities are no longer what they still were 10-15 years ago. Their degree of automation is increasing. Work processes and complete facilities are increasingly networked with each other and with the outside world. More data is collected, transmitted and processed. This is why more and more functions are integrated in slip rings - which therefore increasingly become intelligent transmission systems. Kubler' slip rings offer here ideal solutions both in sensors and in transmission technology. The SR120, SR160 and SR250 product families are Ethernet-capable and reliable. They transmit, besides classical control signals, electrical power up to 120 A and large data volumes in real-time. 
 
High output under efficient production conditions around the clock is decisive for the economic operation of modern investment-intensive production facilities. The trend is moving towards more efficient, self-organizing and resource-saving production facilities. Operating data is comprehensively collected, analyzed and controlled. The question is asked here: How am I doing (how is the facility doing)? Are all values nominal? Is a problem appearing somewhere? Or, in more technical words: are the characteristic values such as temperature, speed, position, acceleration, air humidity and many others in the normal range or not? If this is not the case, even a facility will sooner or later need a pause.

Smartphone and tablet are increasingly used on site to analyze the failure and order the necessary spare parts. We are currently on the way to the cloud. The service technician does no longer have to stand in front of the facility to look for the problem. Plants, plant segments and single components communicate with the outside world and provide even more detail information. The necessary maintenance work becomes predictable. Production can be controlled in a more targeted way. This allows reducing the waste - less time, less resources and of course less money. 
 
What has all this to do with slip rings, and which requirements result from this?

Often, also in the food industry, the main process steps are carried out on rotary indexing tables in order to save space. The electrical power supply of the active elements mounted on the carousels and data communication with other peripheral plant components takes place here via slip rings. The facilities become larger and the carousel counts more and more electrical components. More electrical consumers in the rotating section of the facility means that the slip ring has to transmit more power.

Kubler has taken this into consideration and offers slip ring families for various power classes. The slip rings of the SR120 family can transmit up to 400V-25A, SR160 up to 40A and SR250 up to 120A. But larger facilities including more electrical consumers in the rotating section also mean that the slip ring has to transmit in parallel also many different control signals. The increasing digital networking and the use of Industrial Ethernet, for example for bottling plants including filling, capping and labeling stages, requires slip rings that can be Plugand-Play integrated in an existing network and support real-time Ethernet independently of the data protocol used. Based on our proven contact technologies, we achieve interference-free operation and maximum availability with very long maintenance cycles.

Depending on the application, the devices are maintenance-free for periods up to 5 years, with a very low bit error rate. So much for the basic equipment of the main topic. Condition monitoring is here the means to the end, allowing monitoring continuously the operating condition of important components throughout the facility. The condition of the sliding contacts themselves is the most important point for the proper functioning of a slip ring. Until now, the inspection of these contacts required stopping the facility and partly dismounting the slip ring. This entailed time, specific product knowledge and sometimes special tools. These additional expenses disappear if measures for condition monitoring are integrated in the slip ring besides the pure transmission function.

The customer can monitor from the outside the remaining operating time of the slip ring - during ongoing operation and without having to open the device or even dismantling it from the facility. At Kubler, we developed a simple yet efficient condition monitoring using sensors available on the market. Not only the remaining operating time can be monitored by the customer, but we can also adjust the warning levels according to customer requirements. They can be deeply integrated in the control to allow reducing further the risk of unplanned facility downtimes. 
 
Life-prolonging measures

Many applications are running under more or less moderate climatic conditions. Neither the temperature nor the air humidity show extreme values or fluctuations. But this is not the case for other applications in the food industry. Temperature and humidity are strongly varying. There is here the risk that condensation and dew appear inside the slip ring. In such a situation, the contacts may corrode. Contact safety and service life of electrical contacts in general and of sliding contacts in particular are no longer ensured, or are greatly reduced. In such cases, monitoring the temperature and humidity inside the slip ring makes sense. The integration of adapted sensors and heating elements will allow measuring and controlling the risk of condensation inside the device during operation. The control then decides whether the integrated heating is to be switched on preventively or not. 
 
Integrated additional functions by Kubler

Besides endlessly rotating processes, there are applications in most varied industry sectors that require controlling as accurately as possible positions within one revolution. In such cases, we can provide position and motion sensors in the slip ring, for example singleturn or multiturn absolute encoders, in the form of a ready-to-mount transmission system with various additional functions and position sensors - Plug and Play. 

Where are transmission systems taking us?

It is to be expected that future automation will lead to the increase of data volumes and therefore also of data rates. Transmission rates of 100 Mbps use a contacting transmission technology. For transmissions of 1 Gbps we rely on non-contacting transmission technologies. In both cases, data transmission is protocol-independent; our transmission systems support all usual Industrial Ethernet protocols. The "traditionally passive component" slip ring is increasingly given a more active role. The integration of further functionalities on the way to the IIoT is gaining in importance also for slip rings.