A rotary union that includes rotating and non-rotating machine components, each having a sealing ring, which can together form a mechanical face seal. A rotor disposed on the rotating machine component includes one or more magnets. A sensor array disposed in the housing includes a plurality of sensing elements that are integrated with a control device, a communication device, and a power storage device. The sensor array further includes a magnetic pickup coil disposed to closely overlap the outer periphery of the rotor. When the rotating machine component rotates, the magnet creates a rotating magnetic field that cooperates with the magnetic pickup coil to produce electrical power to operate the sensor array.