In accordance with the invention, {HEAD ~ this object} is achieved by exciting {TAIL ~ the active electrode} with a HF current, measuring and combining values of the partial currents entering the partial electrodes and generating an alarm signal which depends upon a comparison of this combination of the partial currents with a pre set limit value 
is achieved by exciting
In accordance with the invention , { HEAD ~ this object } is achieved by exciting { TAIL ~ the active electrode } with a HF current , measuring and combining values of the partial currents entering the partial electrodes and generating an alarm signal which depends upon a comparison of this combination of the partial currents with a pre set limit value
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH