A tacho generator with an additionally attached mechanical overspeed switch are used for speed measurements and overspeed monitoring at the hoisting gear.
The design of the mechanical overspeed switch dictates a switching tolerance of ± 75 rpm, which leads to inaccuracy at the desired switching point. Moreover, the mechanical overspeed switch only reacts to speeds at 700 rpm and above.
The signal quality of the tacho generator does not offer the precision required.
The customer looked for a replacement solution that corresponds to current state of the art technology.
Based on the experience gained from previous upgrade projects the incremental encoder FG 2 with an integrated electronic overspeed switch (option S) was installed. In addition to the incremental speed value this compact encoder solution offers a factory preset switching speed. The electronic overspeed switch makes significantly more accurate overspeed monitoring possible. The switching speed of 2550 rpm was adopted from the previous solution 1:1.
Not only is the overall length now distinctly shorter, this solution requires no changes to the existing mechanical interface. The entire conversion was implemented quickly and easily.