DISTRIBUTION probe head section.
To ensure functional reliability, measures for both on the probe side and at the driver before and after the DC/DC power modules to effectively attenuate RF coupling.
Receiver circuit Figure 3: Block diagram of the receiver for potential-free voltage measurement.
powerful, interference-free design can be implemented with little effort using analog circuit technology. The design is divided into two circuits, a transmitter and a receiver. The transducer can record a DC voltage of ±30 V max. with a variation period of one second. The current consumption has been minimised to < 85 mA for the transmitter and < 25 mA for the receiver with a voltage supply of 15 V. Both the transmitter and the receiver are electrically isolated, the transmitter between the measurement data acquisition and the signal transmission path and the receiver between the signal transmission path and the data output. Special DC/ DC power modules and digital isolators with galvanic isolation and particularly low parasitic coupling capacitance were used to achieve this isolation in the circuitry. The signal is transmitted between the transmitter and receiver via a two-wire cable. Depending on the electromagnetic environmental hundred meters.
Transmit circuit
Figure 2 shows the block diagram of the transmitter. The circuit is divided into six blocks:
Figure 4: Basic structure of a digital isolator from Würth Elektronik.
1. probe: transducer with voltage divider negative polarity.
2. level shifter: level shifter for the voltage- frequency converter. 3. voltage-frequency converter: digital output signal, frequency dependent on the input voltage.
4. digital isolator: galvanic isolation between measuring potential and interface.
5. interface buffer: low-impedance line driver with balanced output.
6. power supply: DC/DC converter, galvanically isolated converters for the
Figure 3 shows the block circuit of the receiver. 1. input buffer: signal pick-up, signal conditioning with balanced input. The link indicator shows whether there is a detectable connection to the transmitter.
2. digital isolator: galvanic isolation between input signal and secondary signal processing / output interface. Additional galvanically isolated voltage for the input-side buffer. 3. frequency-to-voltage converter: generates an output voltage from a digital signal. The voltage level depends on the frequency of the input signal.
4. interface buffer with polarity indicator: level converter for the output signal. The output signal has a positive polarity, the polarity indicator shows the polarity of the input signal.
5. power supply: DC/DC converter for the secondary-side supply.
Use our in-house mods operation to meet your project’s requirements
Learn more:
hammondmfg.com/mods
uksales@hammondmfg.com • 01256 812812
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