CN201616655U

CN201616655U - Testing circuit for open-phase of three phase power supply

Info

Publication number: CN201616655U
Application number: CN201020105121XU
Authority: CN
Inventors: 付爱喜
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-01-27
Filing date: 2010-01-27
Publication date: 2010-10-27
Anticipated expiration: 2020-01-27

Abstract

The utility model provides a testing circuit for the open-phase of a three phase power supply. The testing circuit comprises a first phase, a second phase, a third phase and a null line, wherein the first phase, the second phase and the third phase are respectively connected with the anodes of a first diode, a second diode and a third diode; the cathodes of the first diode, the second diode and the third diode are connected to the first pin of a photoelectric coupler through a current limit resistor after being connected in parallel; the second pin and the third pin of the photoelectric coupler are respectively connected with the null line and an earth wire; and the fourth pin of the photoelectric coupler is connected to a processor. By adopting the scheme, the first diode, the second diode and the third diode form a half-wave rectifier circuit; and after rectification, phase signals are coupled to the output stage of the photoelectric coupler through the current limit resistor and the photoelectric coupler, and sent into the processor. The processor can distinguish three open-phase and power failure accurately according to states of electrical levels before and after.

Description

A kind of three phase mains lack detection circuit

Technical field:

The utility model relates to phase shortage detection technique field, refers in particular to a kind of three phase mains lack detection circuit.

Background technology:

Existing lack detection circuit adopts the dividing potential drop mode to detect mostly, in actual motion, voltage ripple of power network, line load type and connected mode etc. all can affect greatly lack detection circuit, sometimes, are subjected to the influence of line load, or during voltage ripple of power network, phenomenons such as existing lack detection circuit is easy to generate wrong report, fail to report, and the electronic devices and components that existing lack detection circuit uses are many, complex structure, production cost is higher.

Summary of the invention:

The purpose of this utility model is to overcome the deficiencies in the prior art, provide a kind of simple in structure, production cost is low, the three phase mains lack detection circuit that utilizes phase place to detect.

For achieving the above object, technical scheme provided by the utility model is: a kind of three phase mains lack detection circuit, it includes first phase, second phase, third phase and zero line, first phase, second phase, third phase respectively with first diode, second diode, the positive pole of the 3rd diode is connected, first diode, second diode, be connected on first pin of photoelectrical coupler by current-limiting resistance again after the 3rd diode cathode parallel connection, the crus secunda of photoelectrical coupler, tripod respectively with zero line, ground wire is connected, and the 4th pin of photoelectrical coupler is connected on the processor.

The utility model is after having adopted such scheme, at first, first diode, second diode, the 3rd diode are formed half-wave rectifying circuit, and the phase signal after the rectification is coupled to the output stage of photoelectrical coupler by current-limiting resistance, photoelectrical coupler and is sent in the processor.At three-phase just often, the signal of photoelectrical coupler output all is a low level, lacks a phase time, in the waveform of output signal, and the about 4ms of high mean period, low level is approximately 16ms; And lack two phase times, and in the waveform of output signal, high level is approximately 12ms, and low level is approximately 8ms; And lacking three phase times, output signal all is a high level.Processor is easy to judge the three phase mains state by the time length that high ordinary telegram in the statistics 20ms continues, and processor can be distinguished scarce three-phase and power failure exactly according to the state of front and back.Adopt the employed electronic devices and components of testing circuit behind this programme few, production cost is low, and electric current required during work is extremely low, and caloric value is little, and be not subjected to voltage ripple of power network, loadtype and connected mode influence, testing result is accurately and reliably.

Description of drawings:

Fig. 1 is circuit theory diagrams of the present utility model.

Fig. 2 is the utility model embodiment in the three-phase oscillogram at strong and weak electricity two ends just often.

Fig. 3 is that the utility model embodiment is in the oscillogram that lacks phase time strong and weak electricity two ends.

Fig. 4 is that the utility model embodiment is in the oscillogram that lacks two phase time strong and weak electricity two ends.

Fig. 5 is the oscillogram at the utility model embodiment strong and weak electricity two ends when lacking three-phase or having a power failure.

Embodiment:

The utility model is described in further detail to accompanying drawing 5 below in conjunction with accompanying drawing 1, preferred embodiment of the present utility model is: the described lack detection circuit of present embodiment, it includes the first phase A, the second phase B, third phase C, wherein, the first phase A, the second phase B, third phase C respectively with the first diode D1, the second diode D2, the 3rd diode D3 positive pole is connected, the first diode D1, the second diode D2, be connected on the pin 1 of photoelectrical coupler U1 by current-limiting resistance R1 again after the 3rd diode D3 negative pole parallel connection, two pin 2 of photoelectrical coupler U1, tripod 3 respectively with zero line N, ground wire D is connected, and four pin 4 of optocoupler U1 are connected in the processor.During work, at first, the first diode D1, the second diode D2, the 3rd diode D3 form half-wave rectifying circuit, phase signal after the rectification is coupled to the output stage of photoelectrical coupler U1 and is input to processor by resistance R 1, photoelectrical coupler U1 input stage, the waveform of processor scanning input (referring to accompanying drawing 2 to accompanying drawing 5), when three-phase just often, the signal of (referring to accompanying drawing 2) optocoupler output all is a low level, lack a phase time, in the waveform of (referring to accompanying drawing 3) output signal, the about 4ms of high mean period, low level is approximately 16ms; And lack two phase times, and in the waveform of (referring to accompanying drawing 4) output signal, high level is approximately 12ms, and low level is approximately 8ms; And lack three-phase or when having a power failure, (referring to accompanying drawing 5) output signal all is a high level.Processor is easy to judge the three phase mains state by the time length that high ordinary telegram in the statistics 20ms continues, and processor can be distinguished scarce three-phase and power failure exactly according to the state of front and back.Adopt the employed electronic devices and components of testing circuit behind this programme few, production cost is low, and electric current required during work is extremely low, and caloric value is little, and be not subjected to voltage ripple of power network, loadtype and connected mode influence, testing result is accurately and reliably.

Be that the situation of 50Hz is analyzed at our national supply frequency only below, as adopt other operating frequency, the corresponding cycle is judged the state of three phase mains by (50/ concrete operating frequency) the pairing cycle of * 50Hz.

The embodiment of the above is the preferred embodiment of the utility model only, is not to limit practical range of the present utility model with this, so the variation that all shapes according to the utility model, principle are done all should be encompassed in the protection range of the present utility model.

Claims

1. three phase mains lack detection circuit, it includes first phase (A), second phase (B), third phase (C), zero line (N), it is characterized in that: first phase (A), second phase (B), third phase (C) respectively with first diode (D1), second diode (D2), the positive pole of the 3rd diode (D3) is connected, first diode (D1), second diode (D2), be connected on the pin (1) of photoelectrical coupler (U1) by current-limiting resistance (R1) again after the negative pole parallel connection of the 3rd diode (D3), two pin (2) of photoelectrical coupler (U1), tripod (3) respectively with zero line (N), ground wire (D) is connected, and four pin (4) of photoelectrical coupler (U1) are connected to processor (CPU).