CURRENT MEASURING INSTRUMENT Russian patent published in 1998 - IPC

FIELD: electrical engineering. SUBSTANCE: device has current transformers 1, 2 with magnetic cores 3, 4 and shared winding 26, current generator 8 which output is connected to secondary winding 5 of first current transformer 1. In addition device has unit 20 which controls current generator 8 by means of bias current constituent, current gage 10, 11, which measures current in secondary winding 6 of second current transformer 2 which is proportional to current to be measured. Compensation units which provide compensation for any potential alternations in joint 7 of windings 5 and 6 are designed using amplifier 14, which output is connected through capacitor 16 and resistor 17 to joint 7 and negative input of amplifier 14. In addition device has units for biasing positive input potential of amplifier 14, which is added to signal which is received from output signal of amplifier 14. Voltage which is generated at resistor 17 is applied to unit 20. EFFECT: decreased residual biasing current and any alternations it causes. 2 cl, 1 dwg