Zener Diode For Meter Protection
Zener Diodes are generally employed in multimeters to protect the meter movement against damage for accidental overloads. For the protection of the meter, the zener diode is connected in parallel with it as shown in diagram 1. In a case of accidental overload, most of the current will pass through the zener diode, thus protecting the meter movement from damage. When the meter movement is required to be protected, regardless of the applied polarity (i.e. A.C), the circuit arrangement is modified as shown in diagram 2.