Development Of AC Voltage Output Unit Of Calibration Device For Voltage Monitoring Instrument With High Precision

Voltage monitoring instrument is a main device for voltage qualitymonitoring, the reliability of the voltage monitoring is decided by the veracity andreliability of it.Thus, a dedicated and efficient calibration device for voltagemonitoring instrument is developed, for checking its various performance indicators toplay a decisive role for ensuring its function and guaranteeing the qualified rate ofvoltage.The main function of calibration device for voltage monitoring instrument is tooutput AC voltage with high stability and accuracy which can be adjusted according torequirement. An AC voltage output unit of calibration device for voltage monitoringinstrument was developed in this paper. The unit included microprocessor, electric circuitof signal generator, amplifying circuit, output transformer and negative feedback system.As the control core of the whole system, the microprocessor played the role of controllingand coordinating all kinds of chips to complete their respective functions time sequence:first, to make signal generator circuit to emit a corresponding frequency waveform output,then the waveform was amplified by amplifying circuit.Following that, the voltage wasboosted and range was selected by output transformer, and at last, corresponding voltagewas output according to the range selected. Through sampled and rectified, the outputvoltage was sent into integral regulation circuit, and then compared with the fixed voltagevalue, to lock or adjust the output voltage at the moment, in this way, a closed-loopnegative feedback was constituted, and consequently, a output voltage with high accuracyand stability was achieved. All kinds of chip initialization, panel and key informationcompilation, communication with the central control system, interrupt handling,One-click comprehensive error checking and etc. can be done by the embedded software system, and the flow chart of the main software was given.Prototype of calibration device for voltage monitoring instrument was developedaccording to the design thought and specific methods given in the paper, and its propertieswas tested. The result showed that the AC output of calibration device for voltagemonitoring instrument can satisfy the requirements of the standard calibration device inDL/T500-2009"Specification of voltage monitor for order", the output range was covered57.7-380V with a degree of accuracy above0.1grade, and can output harmonic voltagemore than five times.