Abstract: The invention relates to a system for checking a suspension of solid particles, having a test tube for taking up and sedimentation of the suspension, having--an illuminating radiation source (L),--a test tube (P) is transparent to the illuminating radiation and the radiation emerging thereof, in which test medium is allowed to sediment and which can be located in the radiation path of the system,--optionally, a further test tube (PE), that is transparent to the illuminating radiation and the radiation emerging thereof, in which a reference or calibration liquid is allowed to sediment and which can be located in the radiation path of the system,--a sensor device to detect the illuminating radiation (S.sub.L)--a sensor device for detecting radiation emerging by transmission (S.sub.T) from the test tube(s) (P.sub.E, P)--a sensor device for detecting the radiation (S.sub.F) emerging from the test tube(s) at an angle other than 180.degree.

Abstract: An apparatus is provided for measuring the test current in magnetoelectric fault detection, for instance by the magnetic particle method. A sensor comprising a Hall generator or a magnetoresistor is movably mounted on a diamagnetic support which clamps the sensor at a variable distance from a conductor carrying the test current. Alternatively, a plurality of sensors can be fixed to the support and the appropriate sensor selected for use.