Posted to News on 27th Apr 2017, 13:15
Cable colour coding - understanding the DESINA standard
DESINA stands for DistributEd Standardised INstAllation Technology and is a standard for components used on industrial machines, including the drives, control systems and cabling. It is a great idea with many benefits but, where it relates to cable colour coding, the situation may be a little confusing and there is room for error. Andrew Fallows, managing director of Motor Technology, explains.
The DESINA standard was created by members of the German Machine Tool Builders' Association (VDW) in conjunction with key automotive manufacturers and suppliers. The objectives were to reduce the variety of components, simplify design and avoid errors in assembly; but, when it comes to cable colour coding, ambiguity has recently led to some confusion.
For example, one cable manufacturer, in an attempt to comply with DESINA, recently changed the colour of its cable for feedback on servo systems from orange to green. Although the new green cable was identical, in terms of its specifications, to the previous orange one, it demonstrates how misinterpretation is not uncommon with DESINA colour coding.
In reality the cable manufacturer was not entirely wrong in the first place. According to DESINA, orange cable is for servo systems and so, in this sense, the manufacturer was correct to use an orange sheath for these servo-related cables. The thing is, DESINA also stipulates that all cable that is specifically for measuring and feedback functions should be green, so really the cable manufacturer was, in fact, correct to make the change.
The DESINA standard stipulates the following colour coding for cables used on industrial machinery, plant and equipment:
Screened cables
- Orange, (RAL 2003), for servo applications
- Green, (RAL 6018), for measuring and feedback systems
- Violet, (RAL 4001), for fieldbus and hybrid cables
Unscreened cables
- Yellow, (RAL 1021), for sensors
- Black, (RAL 9005), for power
- Grey, (RAL 7040), for 24V control
The RAL references used by DESINA are taken from a colour-matching system used in Europe mainly for defining varnish and powder coatings. It is used throughout industry and was originally created by the German RAL gGmbH, a subsidiary of the RAL Institute.
Being aware of what the colours are meant to indicate is useful, but it should not be a substitute for being thoroughly aware of a cable's exact specifications and the use for which it was intended. For example, some cable manufacturers are now offering grey cables, with screen, for use as feedback cables. Remember, unscreened grey cables are defined as 24V control cables by DESINA. So, always speak to your cable manufacturer or supplier if you are not sure.
This article was originally published in Motor Technology's newsletter, Motor Technology News.
A PDF download of a DESINA cable colour chart can be found here.
