Keywords: electric point machine, switch malfunction, friction clutch, condition monitoring, switching load, turnout.

Forecasting of switch malfunctions is important issue to advance function of a condition monitoring system for electric point machine. In many of previous monitoring systems, switch malfunctions are detected using threshold, however defining unit of thresholds including motor current to forecast switching malfunction are difficult. Maximum slipping torque of a clutch, which is adjusted by contacting force between slipping plates, on electric point machine can relate to switching malfunctions, however forecasting method of the clutch status have not been developed. In this study, a forecasting method of clutch adjustment status is proposed using monitoring parameters like a motor current and switching time. To confirm relationship between switch malfunction and slipping of a friction clutch, we tested and measured statuses of electric point machine using a 1:12 flexible switch, an actuator for artificial switching load and a NS-A point machine equipping an AC induction motor and a friction clutch. By this test, we confirmed that increment of switching time indicates switch malfunction due to a clutch slipping. It is also confirmed that increment of the maximum motor current in operation indicates switch malfunction due to a motor axis slipping. We proposed a method to find reasons of a switch malfunction such as: clutch slipping and overload of motor by increment of switching load. By these results, we proposed a flowchart of switch malfunction forecast relates clutch adjustment using inrush current, switching time and maximum motor current. The flowchart helps adjustment works of a friction clutch. Moreover, the improvement of a clutch adjustment helps safety of point machines in strength, because a large force by tight adjustments produces a risk of large stress on components of a point machine and rods.

download the full-text of this paper (PDF, 9 pages, 336 Kb)

go to the previous paper
go to the next paper
return to the table of contents
return to the volume description