Centrifugal separator with sensing means

In combination with a centrifugal separator including a rotor having a separating chamber for receiving a mixture of two media to be separated, the rotor being operable to form an interface between the two media undergoing separation in said chamber, an arrangement for sensing a displacement of said interface during operation of the rotor, said arrangement comprising a first unit forming an electric resonance circuit rotating with the rotor and having at least one variable oscillation property, said unit including a sensing member rotating with the rotor and arranged to sense a displacement of said interface and to change said variable oscillation property of the resonance circuit in response to a said displacement, and a second unit separate from the rotor and including means for inductively transferring a signal to the resonance circuit, said second unit also including means for sensing a change of the load by the resonance circuit on said signal transferring means in response to a change of the variable oscillation property of the resonance circuit.