When it goes wrong
It may be a capacitive sensor that becomes affected by condensation, an optical sensor that has become unreliable because the lens system is obscured by dust particles, or a magnetic sensor that no longer works due to hysteresis. When it does go wrong, as an engineer you will immediately ask yourself two questions: “What type of sensor technology do I need to use to stop this happening again?” and “how on earth am I going to find a sensor to retrofit into this very specific space?”. What is needed in this situation is a ‘fit and function’ replacement where a new sensor technology will work in the same mechanical space and with the same electrical interface that is currently in use. Simply put, this usually means a sensor that isn’t going to go wrong in tough conditions and can be a custom shape.
New generation inductive sensors
New generation inductive sensors, such as those made by Zettlex, use the same principles as traditional inductive sensors, offering precise non-contact measurement performance irrespective of the operating environment. One box ticked. Interestingly, however, and a key catalyst for engineers around the world counting on Zettlex sensors is what Zettlex call ‘Shapeability’.
Fig 1 – Zettlex custom sensor example
Zettlex sensors use printed circuits on flexible or rigid substrates, rather than traditional inductive sensors that use bulky spools of wire. The major benefit of this method is that it gives Zettlex the ability to make a sensor of almost any shape. An example of this is in Figure 1 which is a recent miniature rotary encoder custom requirement using a cast iron housing. In this situation the Zettlex sensor is replacing a potentiometer which had become unreliable due to prolonged vibrations causing wear.
When potentiometers fail and are replaced with a non-contact sensor, one issue that arises is that most non-contact sensors have a digital output, not analogue. For an engineer this means additional time and cost spent on requalification. This doesn’t happen if you choose a Zettlex sensor because they use the same electrical interface.
Zettlex’s ‘Shapeability’ position sensing technology is not limited to replacing unreliable sensors. In fact, greater demand than ever is coming from new project design, particularly in situations with cost, weight and size restraints. Position sensors are often the last elements of a design. Invariably, the space available is tight or in an awkward shape – typically with fasteners, cables and connections competing in the sensor’s prime real estate. This often results in the conclusion that the traditional COTS (Commercial-Off-The-Shelf) sensors are simply not going to fit the available space. Gimbal systems are a useful example where there is a tight requirement for space and height, as well as demanding performance accuracy levels.