Honeywell's 3090A35 VRS (Variable Reluctance Speed) magnetic speed sensor is engineered for use in potentially explosive environments. These sensors are simple, rugged devices that don't require an external voltage source. They operate by detecting changes in a magnetic field caused by a ferrous metal target, inducing a current into a coil winding. The output signal is an AC voltage that varies with the speed of the monitored device, making it suitable for applications like engine RPM measurement, motor speed monitoring, and process speed control in industries such as oil and gas, manufacturing, and power generation.