Measuring method and circuitry for testing protective measures in AC networks

摘要

2.1 By measuring methods in which a test current is applied to the protective conductor, dangerous contact voltages can occur in the case of faulty power systems. The danger associated with this is to be eliminated by the invention. 2.2 Into the measuring sequence for determining various measuring quantities, test measurements are inserted with the aid of which the contact voltage (UA) occurring in each case is measured at short intervals. If this voltage exceeds a predetermined limit value (UBL) which corresponds to the limit value of the permissible contact voltage (UB), the test current (IK) is switched off and thus the measuring sequence is interrupted. 2.3 The invention is applied in measuring and test instruments which are equipped with a computer. IMAGE