Measurement method using multimeter protected against over voltge - measuring one or more voltages and determining whether to switch to lower range

摘要

The voltage (Ue) to be measured is applied to one of two input circuits (a,b) connected to a range network of measuring resistances (N) with a range selector switch (S). A control circuit (STS) ensures that irrespective of the setting of this switch the first measurement is made always with the less sensitive circuit. Separate inputs for e.g., voltage (A) and current (B) are switched (3,4) by magnetic relays (M1, M2). The selector (S) is operated (M4) and a warning of over-voltage sounded (SU). ADVANTAGE - Cannot damage meter by appliation of unsuitably high voltages to its input through incorrect range selection.