In the alternating current (AC) operated solenoid valves, the electric current flow through the coil and thus, the resulting magnetic field developed, will vary. This will lead to chatter (oscillation) in the coil. To minimize this chatter, this type of valve employs a shading ring or shading coil .
The basic working principle of a solenoid valve will follow now. A solenoid is actually an electromagnet wherein a wire coil will be wound around a soft movable ferromagnetic iron core. The core will become magnetized due to the flow of an electric current through the electromagnetic coil. A spring will be attached to the core (armature) .
Solenoid valves (SVs) are electrically controlled electromechanical devices used to govern the flow of liquids or gases . Solenoid valve converts electrical energy into mechanical motion or mechanical energy . The schematic representation of the SV cross-section (axisymmetric) is shown in Fig. 1.
The coil degradation or failure modes of the solenoid valves (SVs) were considered during their study at the Oak Ridge National Laboratory. These SVs were utilized in the safety systems of nuclear plants and their functional failure can take place from the coil degradation , .
Utah and Jung considered alternating current (AC) based solenoid valves wherein a method for fault diagnosis was adopted. The authors indicated that the AC signal or waveform of the solenoid valves contains several hidden features.
Closure of the orifice will take place and the fluid flow through the valve will be stopped . In the alternating current (AC) operated solenoid valves, the electric current flow through the coil and thus, the resulting magnetic field developed, will vary. This will lead to chatter (oscillation) in the coil.