| 摘要 |
<p>PURPOSE:To provide a current measuring device which can be drive by a single power supply and which prevents an apparatus as a whole from becoming large. CONSTITUTION:A Hall element 16 which is situated inside a gap 14a for a yoke 14 generates Hall voltages VH whose polarity differs according to the direction of a current flowing in a bus 15 to be measured. A first amplifier 18 and a second amplifier 18b amplify the Hall voltages VH whose polarity is opposite to each other, and they turn on any of a combination of transistors 20, 23 and that of transistors 21, 22 inside a coil-current control circuit 19. The coil-current control circuit 19 makes a negative-feedback current in the direction of an arrow C flow to a coil 11 for magnetic balance in a stake that the transistors 20, 23 are turned on, and it makes a negativefeedback current in the opposite direction of the arrow C flow to the coil 11 for magnetic balance in a state that the transistors 21, 22 are turned on.</p> |
