The Seam detector is designed for use on most types of fabric dyeing
machines. A sensor unit is mounted on the outside of the machine at
a point near to where the fabric passes. A Metal is sewn into the fabric
seam and this triggers the sensor when it passes. A relay is activated
in a separate amplifier unit for about 2 seconds, and the volt free
changeover contact on this relay may be used as required. Typical
uses include stopping the machine when the seam is found for unloading,
or checking that the fabric is circulating within a particular time frame.