Sheet break detection on the paper machine is a critical task requiring precision and speed of detection. Precision is required because a false break indication can cause a break, speed is essential to avoid damage to press rolls, paper rolls or calenders and to reduce the clean-up time before the machine can be rethreaded. Reliable detection reduces machine stop time to improve productivity and operator safety. The simplest method of detection is a photoelectrical cell at an open draw, a very economical solution but not foolproof, it requires access to both sides of the sheet and scraps of paper from a break can block the light transmission. Reflective infrared sensors have also been used to measure the paper in an open draw or on a roll, but can have difficulties when the sheet is backed by a felt fabric; the reflective difference between paper and felt can be quite small and the all too important precision is lost.