Serial zero load current phase measuring instrument

Abstract

The invention relates to a serial zero load current phase measuring instrument, which consists of a sampling part, a display part, a central processing unit, a keyboard part, a current amplification part and an instrument shell. The sampling part comprises a divider resistor and a current transformer, wherein the divider resistor samples a voltage; and the high-precision split core type current transformer samples a current. The display part consists of a 128*64 dot-matrix liquid crystal and can display parameters and graphs. The central processing unit uses an MSP430 high-performance singlechip as a central control element and can complete sampling computation and analysis at the same time. The test instrument has three keys, the operation of the three keys corresponds to the liquid crystal, the liquid crystal can give a prompt for the function of each key, and the operation is simple. The current amplification unit can amplify a current by 10 times for measuring smaller current (20Ma) apparatuses and can adopt the split core type current transformer for measuring the phase of a current or adopt direct wiring for measuring the phase of a small current, and the measurement is accurate and convenient. The instrument shell can be used for assembling the elements. The surface of the instrument shell is provided with a pincerlike galvanometer interface, a negative voltage input terminal, a positive voltage input +, a change-over switch, a current transducer, an amplifier current input, an amplifier current output, a switch and a charging port. The instrument is convenient and accurate and can reduce human errors.

Description

technical field [0001] The invention relates to a device for measuring the amplitude and phase of a secondary capacitor current of a relay protection device, in particular to a series-connected zero-load current phase measuring instrument, which belongs to the technical field of electric equipment detection. Background technique [0002] In the power system, the relay protection device is an important guarantee for the normal operation of the power system, but the secondary wiring of the relay protection device is cumbersome and prone to various errors. It is an important and cumbersome job to check the correctness of wiring on site. The traditional instrument for measuring the phase of the secondary current adopts the clamp measurement method, that is, the amplitude and phase of the current are measured by clamping the core wire of the secondary current with a clamp clip. When the transmission line is not loaded, because only a small number of lines pass through Capacitive...

AI Technical Summary

Problems solved by technology

[0002] In the power system, the relay protection device is an important guarantee for the normal operation of the power system, but the secondary wiring of the relay protection device is cumbersome and prone to various errors

It is an important and cumbersome job to check the correctness of wiring on site

The traditional instrument for measuring the phase of the secondary current adopts the clamp measurement method, that is, the amplitude and phase of the current are measured by clamping the core wire of the secondary current with a clamp clip. When the transmission line is not loaded, because only a small number of lines pass through Capacitive current to ground, the current value is very small, the reaction to the secondary side is only about 10mA, the measurement accuracy of the clamp ammeter decreases, and the amplitude and phase of the current cannot be correctly reflected, resulting in measurement failure. Only after the line is loaded can it be Correct measurement, but it takes a long time to wait for the increase of load, which seriously affects the measurement efficiency

In addition, the traditional clamp-on ammeter needs to clamp the clips into the current core wires during measurement. If the core wires are arranged densely, the adjacent current core wires may be squeezed out of the terminal block when clamping the clips, causing the current to open, forming high voltage and endangering personal life. and device security

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