Patent ID: 8604805

Claim:
A property monitoring apparatus incorporated in a measurement device for monitoring a property of a current transformer or a voltage transformer used in the measurement device, comprising: a test current output circuit configured to vary an output current and output a test current; a test current value computing device configured to compute a current value of the test current outputted from the test current output circuit when the test current outputted from the test current output circuit is supplied to the current transformer or to the voltage transformer; a test current control device configured to perform a feedback control of the test current value computed by the test current value computing device to a target value; a measurement current detection circuit configured to measure an output current value of the current transformer or the voltage transformer when the test current controlled to the target value by the test current control device is supplied to the current transformer or to the voltage transformer; a storage configured to store a relationship between the measured current value of the measurement current detection circuit and the test current value computed by the test current value computing device for each of a plurality of target values by varying the test current in a predetermined pattern; a correction coefficient computing device configured to compute a correction coefficient for correcting a property of the current transformer or the voltage transformer based on the stored relationship between the computed test current value and the measured current value, and an inspection mode selection device configured to: select an inspection mode, and when the inspection mode is selected, supply a test current having a pattern set in advance to the current transformer or to the voltage transformer, compare a relationship between a present test current value and a measured current value with a relationship between a previous test current value and a previous measured current value, stored in the storage, and perform an inspection based on a result of the comparison.