Distribution transformer grounding resistor, current online measurement equipment and method thereof

Abstract

The invention relates to a distribution transformer grounding resistor, current online measurement equipment and a method thereof. The equipment comprises a sampling circuit, a low pass filter, a switch capacitance filter, a PGA circuit, a DSP and an excitation circuit. The sampling circuit, the low pass filter, the switch capacitance filter, the PGA circuit, the DSP and the excitation circuit are sequentially connected. The equipment also comprises a communication interface module or a display interface module. The communication interface module or the display interface module is connected to the DSP. Hardware maximization of the equipment adopts a digital signal processing technology so that a disadvantage of hardware filtering is overcome. The method is a measurement and calculating method which uses a signal processing system formed by the switch capacitance filter, the programmable amplifier (PGA) and the DSP to realize carrying out digital filtering on a sampling signal and calculates an effective value based on a sine wave.

Description

technical field [0001] The invention relates to a measuring device and a measuring method, in particular to an on-line measuring device and method for the grounding resistance and current of a distribution transformer (transformer in a station area). Background technique [0002] A device that can monitor whether the grounding wire is in good contact in real time. It can detect abnormal grounding resistance of distribution transformers in time, inform users of hidden dangers, quickly deal with equipment failures, and prevent accidents. [0003] Some products on the market are not monitored in real time online. Even the equipment with real-time online monitoring generally has large measurement deviations, is greatly affected by temperature, has a small measurement range, and has problems such as inaccurate measurement. [0004] Longyuan's I-generation product can monitor the changes of grounding resistance and current value online in real time. However, this product is design...

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Problems solved by technology

[0003] Some products on the market are not online real-time monitoring, even real-time online monitoring equipment generally has a large measurement deviation, which is greatly affected by temperature, the measurement range is small, and the measurement is not accurate.

[0004] Longyuan's I-generation product can monitor the changes of grounding resistance and current value online in real time. However, this product is designed in the shape of a circular cylinder, not only has a small inner circle, but also has no external interface. module for maintenance

Moreover, the implementation of the circuit is complex, generally through several stages of amplification, several stages of hardware filtering, and then, an effective value rectification circuit or a peak hold circuit is input to the AD sampling of the single-chip microcomputer to calculate the effective value. Temperature interference affects measurement accuracy

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