Double layered bell jar type voltage and current sensor

Abstract

The present invention relates to a double layered bell jar type voltage and current sensor, comprising an insulation bracket, an inner metal jar, an outer metal jar, a primary current carrying conductor and a secondary current coil, wherein the two metal jars are arranged on the insulation bracket in the same axial direction; the outer metal jar is sheathed outside the inner metal jar; a reception chamber is arranged in the insulation bracket and the inner metal jar; the outer surface of the outer metal jar is fixed with the primary current carrying conductor in a winding way; the inner metal jar is grounded and is internally provided with the secondary current coil at the position with equal altitude with the primary current carrying conductor; and the secondary current coil is connected with a drawn cable located in the inner metal jar, the inner metal jar is also connected with a lead for measuring output voltage; and the present invention is characterized in that: two insulation rings in the inner metal jar and the reception chamber is divided into three parts. The special structure of the double layered metal jar shield cause the low voltage measurement circuit inside the inner metal jar to be less influenced by the external. The measurement circuit can work reliably and stably, the change of intrinsic standoff ratio and current ratio, thus the present invention is suitable for current and voltage levels in a larger scale.

Description

technical field [0001] The invention relates to a sensor for measuring high voltage and large current, in particular to a double-layer bell jar type voltage and current sensor, which is used for measuring high voltage and current, and is used for measurement, protection and monitoring of power systems of 10kV and above. Background technique [0002] With the rapid development of the domestic power system, digital substations representing the highest level of substation automation technology have begun to enter engineering applications in large numbers. One of the main conditions for realizing a digital substation is: the primary equipment is intelligent, and the transformer used to measure voltage and current is a key part of it. At present, electronic transformers or fiber optic transformers are mainly used at home and abroad. Most of the existing electronic transformers use multi-stage capacitors in series to divide voltage to measure voltage, and use Rogowski coils to mea...

AI Technical Summary

Problems solved by technology

Electronic voltage transformers with multi-stage capacitors in series use small capacitance, which is easily disturbed by external distributed capacitance, and is greatly affected by external factors such as temperature, humidity, electromagnetic field, pollution, etc., and the voltage division ratio is prone to drift; If the capacitance used is large, the response speed will not increase, and the problem of charge storage will seriously affect the reclosing

As the Rogowski coil of the current transformer is set on the high-voltage bus, the insulation treatment is difficult, and the low-voltage measurement circuit is easily affected by the high voltage.

[0003] At present, some transformers in China use the principle of capacitive voltage division to measure voltage, and some use improved columnar capacitor rings outside the conductive lines to achieve it. Rogowski coils measure current. The combined electronic voltage and current transformers with this type of structure still have the following problems: The high-voltage current-carrying conductor passes through the overall structure, seriously affecting the low-voltage circuit, the combined structure is complicated, the high-voltage insulation treatment is difficult, the measurement stability is poor, and the manufacturing cost is also higher, which is not conducive to the industrial application of electronic voltage and current transformers

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