JEMTECH says it recently faced an unusual technical requirement to determine the position of an overhead crane, which it solved with the VSY contactless safety switches.
The safety system needed to know if the crane was inside or outside a zone. When inside the safety zone, special conditions had to be applied to the operation of the crane hoists.
The VSY contactless safety switches were used. The conventional solution meant fitting the key on the crane and the switch in a stationary position.
However, this would not be suited for the safety requirements, because if the key was not detected, the crane could move in and out of zone undetected.
In all safety switch applications, the switch had to be used so that it was closed except when the unsafe condition occurred. Jemtech fixed the key and the switch so that detection occurred all the time.
Therefore, failure of the switch or the key would result in detection of the crane as being in zone and therefore safe. By passing a metal flag between the key and switch to interrupt the sensor, electrically reliable mechanical and electronic detection is possible.
Jemtech provided a solution that moulded the key and switch parts into a single robust housing. This housing has a 100mm deep throat with a 30mm opening. This provides a large space for the metal flag to travel through and guarantee the positive breaking of the switch.
A total of four switches were fitted to this application and have successfully enabled the client to detect the position of the crane.
The new parts are called VSSL safety switches and are available from JEMTECH now.