Influence of Supply Voltage Test Equipment ‘ISVT 01’ is used to measure and analyze the influence of supply voltage on energy meter. This test is described in various standards for energy meters such as IS 13779, IEC 62053 etc. As per CEI / IEC 62053-21, IS 13779 clause 12.7.2: The test shall be carried out under the following conditions: 1. Meter in operating condition. 2. Voltage and auxiliary circuits energized with reference voltage.3. Without any current in the current circuits.