A monitoring device for monitoring an impedance of a protective conductor. The monitoring device has a first voltage divider for connection to a voltage source including a series connection to a first resistor and a second resistor. The second resistor has a resistance value which corresponds to a threshold value for the impedance of the protective conductor. A second voltage divider includes a series connection to a third resistor and a bridge diode and a connection to the first resistor at a first end of the third resistor and connectable to a second end of the third resistor and to the protective conductor. A measuring device is provided for the detection of a bridge voltage between a first node and a second node if the impedance of the protective conductor is greater than the value of the second resistor.

A method and an apparatus for calculating an offset of a Wheatstone bridge type sensor are described. The offset calculation method includes measuring resistances between nodes of a Wheatstone bridge type sensor, calculating an offset of the sensor using the measured resistances and providing information on the calculated offset. Accordingly, the offset of the Wheatstone bridge type sensor can be rapidly and easily calculated independently from the size of a bias current, and ultimately. Furthermore, time required to measure can be reduced and thus a sensor fabrication cost can be reduced, and also, mass production can be enhanced.

Example embodiments relate to sensor readout systems and sensor readout methods. One example sensor readout system includes a signal generator configured to generate a biasing signal. The sensor readout system also includes a first chopper configured to modulate the biasing signal using a chopping signal with a chopping frequency f.sub.chop to generate a modulated biasing signal. Additionally, the sensor readout system includes a Wheatstone bridge circuit that includes resistive branches. At least one of the resistive branches includes an impedance-based sensor. The Wheatstone bridge circuit is configured to receive the modulated biasing signal and to generate a sensing signal based on the modulated biasing signal. Further, the sensor readout system includes a second chopper configured to modulate the sensing signal using the chopping signal with the chopping frequency f.sub.chop to generate a modulated sensing signal.

According to aspects of the present disclosure there is provided an apparatus and method for sensing. The apparatus includes a sensor circuit which includes a first output terminal, a second output terminal and a sensor that is provided in a bridge circuit arrangement. The sensor circuit is configured such that a sensor measurement can be determined based on a voltage difference between first and second output terminals. The apparatus is configured so as to prevent a current from being able to flow from the first output terminal through the sensor circuit to the second output terminal.

According to aspects of the present disclosure there is provided an apparatus and method for sensing. The apparatus includes a sensor circuit which includes a first output terminal, a second output terminal and a sensor that is provided in a bridge circuit arrangement. The sensor circuit is configured such that a sensor measurement can be determined based on a voltage difference between first and second output terminals. The apparatus is configured so as to prevent a current from being able to flow from the first output terminal through the sensor circuit to the second output terminal.

A detecting device includes: a bridge circuit having at least one sensing resistor whose resistance varies according to a physical quantity of a measurement object; a power supply configured to apply a voltage to the bridge circuit; an instrumentation amplifier configured to receive an output voltage of the bridge circuit from high-impedance input terminals, amplify the received output voltage, and output the amplified output voltage; and a physical quantity calculating unit configured to receive the output voltage amplified by the instrumentation amplifier and calculate the physical quantity based on the output voltage. The bridge circuit is connected to the instrumentation amplifier via a connector.

A detecting device includes: a bridge circuit having at least one sensing resistor whose resistance varies according to a physical quantity of a measurement object; a constant voltage power supply configured to apply a constant voltage to the bridge circuit; a first amplifier having high-impedance input terminals and configured to receive an input voltage of the bridge circuit from the input terminals, amplify the received input voltage and output the amplified input voltage; and an input voltage monitoring unit configured to receive the input voltage amplified by the first amplifier and monitor the voltage of the input voltage. The bridge circuit is connected to the first amplifier via a connector.

Embodiments are directed to techniques for providing a user-selected target resistance across a set of output terminals of a resistance-generating apparatus. The techniques include (a) assigning a first arrangement of resistance circuitry of the resistance-generating apparatus that nominally provides the target resistance based on known resistance values of a plurality of resistors of the resistance circuitry, (b) configuring the resistance circuitry according to the assigned first arrangement, thereby providing a first resistance across output terminals, (c) subsequently, receiving a resistance measurement from a measurement device configured to measure the first resistance, (d) in response to receiving the resistance measurement, assigning a second arrangement of the resistance circuitry based on a difference between the target resistance and the resistance measurement, and (e) configuring the resistance circuitry according to the assigned second arrangement, thereby providing a second resistance, the second resistance being closer to the target resistance than was the first resistance. Systems and apparatuses are also provided.

A method includes selectively coupling first and second input nodes of a capacitive bridge to first and second voltages, respectively, and selectively coupling first and second output nodes of the capacitive bridge to first and second output terminals, respectively, during a first phase of a clock cycle. The method further includes selectively coupling the first and second input nodes to the second and first voltages, respectively, and selectively coupling the first and second output nodes to the second and first output terminals, respectively, during a second phase of the clock cycle.

Precision AC and DC voltage, current, phase, power and energy measurements and calibrations with current ranges from 1 uA to 20 kA and voltage ranges from 1V to 1000 kV are now performed with accuracies of better than one part per million. Continued demand for improved accuracy has led the inventors to address remnant magetization within the current comparators that form the basis of the measuring process within many of the measurement instruments providing the precision AC and DC measurements and calibrations. Accordingly, the inventors present current comparator and measurement system architectures together with control protocols to provide for correction of this remnant magnetization.