A new range of draw wire (string pot) sensors is now available, which offers users an unrivalled combination of compactness, low cost and large measuring range. The sensor was developed specifically for high volume OEM applications such as mobile cranes, fire rescue vehicles, mobile working platforms and scissor lifts.
Micro-Epsilon’s new wireSENSOR MK88 is an extension of the company’s existing MK Series of draw wire sensors. The MK88 weighs just 400g (including cable) and has a very compact sensor housing that measures just 88x90x90mm. The sensor is available in three measuring ranges: 2300mm, 3500mm and 5000mm, each with output options of potentiometric (P), 0-10V (U) or 4-20mA (I). The MK88 comes with an integrated cable, but this can be changed to a connector in OEM applications if required. The sensor can also be supplied as a mechanical-only option for mounting to the user’s own encoder. A universal encoder mounting plate is used to mount the sensor to the encoder.
Chris Jones, Managing Director at Micro-Epsilon UK Ltd comments: "For OEMs, the MK88 offers the most attractive combination of compact size, robustness and a large measuring range currently available on the market. To my knowledge, there is no other draw wire sensor that offers this level of performance at such a low cost. The compactness of the sensor also means it can be easily retrofitted to existing installations or can be mounted to small design envelopes where available space is tight."
The MK Series of draw wire sensors all benefit from a PA-coated stainless steel wire and a high strength, glass fibre-reinforced plastic housing. This results in an extremely robust sensor that is suitable for all outdoor applications, with a maximum protection class of IP65. Operating temperature is from -20 deg C to +80 deg C, although a special version can be requested down to -40 deg C.
As Chris Jones adds: "The MK88 currently uses an aluminium protection cap, but from the beginning of 2012, this will be replaced by a plastic cap as standard. However, the aluminium cap will still be available as an option."
The principle of a draw-wire displacement sensor is relatively simple, hence its inherent reliability. A draw-wire sensor works in a similar way to a tape measure, except the user does not have to read off the measurement of the extended tape. The rotation of the drum on which the steel wire is wound is measured automatically and the measurement signal is output in either analogue or digital formats. The drum itself incorporates a long-life spring drive, which ensures the steel wire is rewound.