YHW150 intrinsically safe roof displacement monitoring alarm YHW150 intrinsically safe roof displacement monitoring alarm monitoring for coal mine roadway surrounding rock roof settlement fractured and so intelligent instruments, with function monitoring and alarms. It is the traditional mechanical separation monitor, ideal roof settlement dynamic instrument alternative. Features: It has small size, easy operation, visual display, no maintenance and long life, long-term use in underground. The main parameters: Parameter Measurement Range Accuracy install anchor hole diameter Rated voltage current display mode parameter value 0 ~ 150mm 级 4 28,42mm 6.0V ≤130mA 4-digit LED