High resolution for greater insight
Moisture streaks in a paper machine’s cross direction often indicate there are problems with felts, wires, coating stations or CD moisture actuators. High resolution moisture measurement resolves these streaks, and can also help system engineers define a better process model for improved CD control performance. The HPIR sensor measures moisture streaks as narrow as 4 mm and displays them clearly on the ABB QCS profile displays and contour maps.
Broadband performance advantage
Until now, infrared moisture sensors have been designed to mechanically block the measurement beam at high frequency to suppress background radiation. Known as beam chopping, this method reduces signal-to-noise ratio by a minimum factor of two. In addition, the chopping frequency places a fundamental Nyquist frequency limit on the measurement bandwidth. HPIR measurement is different – it does not chop. While measuring, HPIR continuously measures and simultaneously compensates for background radiation, boosting signal and measurement rate. This combination of high spatial resolution and high measurement rate ensures that HPIR does not miss anything while providing an accurate and precise measurement of transient moisture features.
A more reliable and robust sensor design means less paper machine downtime for troubleshooting or swapping sensors. HPIR is air-cooled and has no continuously moving parts. The sensor’s modular design allows for field replacement of modules, avoiding repairs at the manufacturer’s shop, and eliminating the need to stock a complete spare sensor.