A Vibration Switch, in its most basic form, is a device that measures a single vibration parameter and provides a “Go / No Go” indication for operation of the machine. This indication is normally provided through a contact relay of some type and the set-point for engagement is user adjustable. Vibration Switches come in three different types: Mechanical, Electronic, and Digital.
A Mechanical Switch is mounted directly on the machine or machine frame and uses an inertia sensitive mechanism that will respond to physical motion (i.e. Acceleration). These devices provide a Shutdown circuit only. They are simple, very low-cost, and normally require no external power. They have very limited features and capabilities.
An Electronic Switch is mounted either on the machine or close by and uses an accelerometer and electronic circuitry to provide significantly enhanced capabilities as compared to the Mechanical Switch. These additional capabilities include monitoring in Velocity, having both an Alarm and a Shutdown Circuit (often with delays), and providing Vibration Monitoring capability via a 4-20 mA output. These devices are more complex than the simple Mechanical Switch and therefore are more expensive. Electronic Switches require external power.
Digital Switches are essentially single channel monitoring systems that are designed to behave like Electronic Switches. They have programmable circuitry and added capabilities when compared with an Electronic Switch including the ability to be fully configured by the user and often have a local display option.