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