| 摘要 |
In the case of a direct current transmission circuit without auxiliary energy for DC-isolated transmission and/or conversion of the magnitude of a measurement current, the measurement current is converted into alternating current by means of at least two switching transistors (9, 10) whose bases are alternately switched on by means of a control circuit (15, 18-20), is transmitted by means of a transformer (3) and is rectified again on the secondary side of the transformer (3). In order to reduce measurement errors in the transmission circuit, it is ensured that the control voltages on the bases of the switching transistors (9, 10) and the voltage on the transformer (3) are sinusoidal when the measurement currents are small and that, when the measurement current rises, these voltages make a continuous transition from the sinusoidal form into a largely rectangular form. <IMAGE>
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