Phase verification instrument and phase verification method before distribution network connection

Abstract

The present invention discloses a phase check instrument before the connection of a distribution network, comprising a microcontroller, a wire clamp, a color-changing indicator light module, a master-slave switching switch, a voltage acquisition device, a current acquisition device, a DC power supply, a shorting relay, a positive power supply switching relay, a negative power supply switching relay, and an A / D conversion comparison module. When in use, when the two phases on the host side are short-circuited, when the voltage is added to the same two phases corresponding to the slave side, the existence of current can be detected in the loops of the two phases, and the phase that cannot be detected is the same phase line as the phase that is not short-circuited on the host side. The present invention enables the correctness of the phase sequence to be checked without power transmission at both ends of the line, thereby avoiding failures and power outages caused by construction errors.

Description

Technical Field

[0001] The invention relates to a phase checking instrument and a phase checking method before distribution network splicing, belonging to the technical field of electric power detection equipment. Background Art

[0002] After the distribution network line is completed and connected, if the phase sequence is incorrect, it will have a great impact on the power grid, causing fault tripping and reducing power supply reliability. Therefore, it is necessary to check the phase of the construction line before connecting, but there is no reliable means to check the phase sequence of the line from the completion of the line construction to the connection before the connection in the existing technology. It can only be judged by manual experience whether the phase is connected incorrectly, and then the result of experience judgment is used for verification before the connection. Because when checking the phase, one end of the completed line must have been powered on, and after the power is supplied, some users will have used electricity. If the wiring is wrong, a power outage is required for adjustment, which may cause another power outage and a longer power outage, causing inconvenience to users and reducing satisfaction. Summary of the invention

[0003] The purpose of the present invention is to provide a phase checking instrument and phase checking method before distribution network splicing, so that the correctness of the phase sequence can be checked without power transmission at both ends of the line, thereby avoiding failures and power outages caused by construction errors.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A distribution network pre-connection phase check instrument, comprising a microcontroller, a wire clamp A, a wire clamp B, a wire clamp C, a color-changing indicator light module LA, a color-changing indicator light module LB, a color-changing indicator light module LC, a master-slave switch K, a voltage acquisition device V1, a voltage acquisition device V2, a voltage acquisition device V3, a current acquisition device A1, a current acquisition device A2, a current acquisition device A3, a sliding rheostat R1, a sliding rheostat R2, a sliding rheostat R3, a DC power supply, a relay RA, a relay RB, a relay RC, a positive power switching relay VA1, a positive power switching relay VB1, a positive power switching relay VC1, a negative power switching relay VA2, a negative power switching relay VB2, a negative power switching relay VC2, a first A / D conversion comparison module, a second A / D conversion comparison module, and a third A / D conversion comparison module;

[0006] The two ends of the voltage acquisition device V1 are connected between the wire clamp A and the wire clamp B, the two ends of the voltage acquisition device V2 are connected between the wire clamp B and the wire clamp C, the two ends of the voltage acquisition device V3 are connected between the wire clamp A and the wire clamp C, one end of the current acquisition device A1 is connected to the wire clamp A, and the other end of the current acquisition device A1 is connected to the fixed end of the sliding rheostat R1, one end of the current acquisition device A2 is connected to the wire clamp B, and the other end of the current acquisition device A2 is connected to the fixed end of the sliding rheostat R2, one end of the current acquisition device A3 is connected to the wire clamp C, and the other end of the current acquisition device A3 is connected to the fixed end of the sliding rheostat R3, one end of the relay RA is connected to the sliding rheostat R3 The sliding end of the relay RA is connected to one end of the relay RB, the other end of the relay RB is connected to the sliding end of the sliding rheostat R2, one end of the relay RC is connected between the relay RA and the relay RB, the other end of the relay RC is connected to the sliding end of the sliding rheostat R1, one end of the normally open contacts of the positive power switching relay VA1, the positive power switching relay VB1, and the positive power switching relay VC1 are respectively connected to the sliding ends of the sliding rheostat R1, the sliding rheostat R2, and the sliding rheostat R3, and the other ends of the normally open contacts of the positive power switching relay VA1, the positive power switching relay VB1, and the positive power switching relay VC1 are all connected to the positive electrode of the DC power supply;

[0007] One end of the normally open contacts of the negative power switching relay VA2, the negative power switching relay VB2, and the negative power switching relay VC2 is connected to the sliding ends of the sliding rheostat R1, the sliding rheostat R2, and the sliding rheostat R3, respectively, and the other ends of the normally open contacts of the negative power switching relay VA2, the negative power switching relay VB2, and the negative power switching relay VC2 are all connected to the negative electrode of the DC power supply;

[0008] The voltage signal collected by the voltage acquisition device V1 and the current signal collected by the current acquisition device A1 are respectively input into the first A / D conversion comparison module, the voltage signal collected by the voltage acquisition device V2 and the current signal collected by the current acquisition device A2 are respectively input into the second A / D conversion comparison module, the voltage signal collected by the voltage acquisition device V3 and the current signal collected by the current acquisition device A are respectively input into the third A / D conversion comparison module, and the comparison result output terminals of the first A / D conversion comparison module, the second A / D conversion comparison module and the third A / D conversion comparison module are connected to the data input terminal of the microcontroller;

[0009] The power input ends of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC are powered, and the microcontroller outputs control signals to the control input ends of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC, respectively, to control the lighting and luminous color of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC;

[0010] The master-slave switching switch K is connected to a microcontroller, and the relays RA, RB, RC, positive power switching relay VA1, positive power switching relay VB1, positive power switching relay VC1, negative power switching relay VA2, negative power switching relay VB2, and negative power switching relay VC2 are each configured with a MOSFET tube, and one end of the relay RA coil, relay RB coil, relay RC coil, positive power switching relay VA1 coil, positive power switching relay VB1 coil, positive power switching relay VC1 coil, negative power switching relay VA2 coil, negative power switching relay VB2 coil, and negative power switching relay VC2 coil is connected to a power supply VCC, and the other ends of the relay RA coil, relay RB coil, relay RC coil, positive power switching relay VA1 coil, positive power switching relay VB1 coil, positive power switching relay VC1 coil, negative power switching relay VA2 coil, negative power switching relay VB2 coil, and negative power switching relay VC2 coil are respectively connected to the D pole of the MOSFET tube configured respectively, the S pole of each MOSFET tube is grounded, and the G pole of each MOSFET tube is respectively connected to the microcontroller.

[0011] A phase verification method of a phase verification instrument before a distribution network is spliced, comprising the following steps:

[0012] The wire clamps A, B and C of the host are connected to the three phases A, B and C of the fixed phase sequence end respectively. After the host and the slave are turned on, the color-changing indicator light LA ​​module, the color-changing indicator light LB module and the color-changing indicator light LC module of the host are respectively lit in yellow, green and red; the host side short-circuits the two phases B and C, and the slave starts the discrimination program. After the discrimination program is completed, the slave lights the color-changing indicator light module of the phase without current to yellow, and then the slave side applies a pulse voltage between the phase with current and the phase without current for n seconds. After n seconds, the slave enters the next discrimination program;

[0013] After receiving the pulse voltage signal, the host disconnects the short-circuit connection between phases B and C and short-circuits phases A and C instead. The slave starts the discrimination procedure. After the discrimination procedure is completed, the slave lights up the color-changing indicator light module of the phase without current to green. Then, the slave adds a pulse voltage signal between the phase with current and the phase without current for n seconds. After n seconds, the slave enters the next discrimination procedure.

[0014] After the host receives the pulse voltage signal, it disconnects the short-circuit connection between phases A and C and changes to short-circuit phases A and B. The slave starts the identification program. After the slave identification program ends, the slave lights up the color-changing indicator light module of the phase without current to red. Then the slave side applies a pulse voltage between the phase with current and the phase without current for n seconds. After n seconds, the slave ends the program. After the host receives the pulse voltage signal, it ends the program.

[0015] The slave identification method is as follows: when the host short-circuits two phases, the slave applies voltage between phases AB, between phases BC, and between phases AC in turn to detect whether there is current in phases A, B, and C. The sequence is checked three times. The phase without current means that the host has not short-circuited the phase. The slave lights up the color-changing indicator light module corresponding to the wire clamp connected to the phase and displays the corresponding color. A corresponds to yellow, B corresponds to green, and C corresponds to red.

[0016] The purpose of the present invention can also be further achieved by the following technical measures:

[0017] The internal structures of the aforementioned distribution network connection front phase meter, the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC are as follows: including a red-green dual-color light-emitting diode, two current-limiting resistors, and two MOSFET tubes. The model of the red-green dual-color light-emitting diode is LTST-C195KGJRKT. The anode of the red-green dual-color light-emitting diode is connected to the positive pole of the power supply. The two cathodes of the red-green dual-color light-emitting diode are respectively connected in series with the current-limiting resistors configured respectively, and then connected to the D poles of the MOSFET tubes configured respectively. The S poles of the two MOSFET tubes are both grounded, and the G poles of the two MOSFET tubes are respectively connected to the control ports of the microcontroller.

[0018] The internal structure of the above-mentioned distribution network connection front phase meter, the first A / D conversion comparison module, the second A / D conversion comparison module, and the third A / D conversion comparison module is: including an A / D converter and a comparator, the output end of the A / D converter is connected to the input end of the comparator, the comparison input end of the comparator inputs a comparison reference signal, and the output end of the comparator outputs a comparison result to the microcontroller.

[0019] Compared with the prior art, the invention has the beneficial effect of enabling the phase sequence to be checked without power transmission at both ends of the line, thereby avoiding phase sequence failure and power outage again caused by construction errors. The phase checking method is simple, the indication is clear, and the accuracy is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the circuit principle diagram of the nuclear phase instrument of the present invention;

[0021] Figure 2 It is the principle diagram of the control circuit of the nuclear phase instrument of the present invention;

[0022] Figure 3It is the wiring diagram of the master and slave;

[0023] Figure 4 It is the host program flow chart;

[0024] Figure 5 This is the slave program flow chart. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] The basic basis of the design of the present invention is:

[0027] At both ends of the bonding line (on the switch cabinet or overhead line), the bonded object must have clear ABC three-phase indications:

[0028] Inside the switch cabinet: The insulation of the overlapping pile head is marked with yellow, green, red or other colors. Even if there is no mark, the phase sequence of other adjacent outgoing line intervals can be seen through the observation window of the rear door of the adjacent operating interval switch cabinet, so the phase sequence on the switch cabinet side can be determined. Overhead line: In the direction of current flowing out of the substation, the order from left to right is A, B, and C, so the phase sequence of the operating line can also be determined.

[0029] like Figure 1 , 2 As shown, the phase analyzer before the distribution network connection includes a microcontroller, a wire clamp A, a wire clamp B, a wire clamp C, a color-changing indicator light module LA, a color-changing indicator light module LB, a color-changing indicator light module LC, a master-slave switching switch K, a voltage acquisition device V1, a voltage acquisition device V2, a voltage acquisition device V3, a current acquisition device A1, a current acquisition device A2, a current acquisition device A3, a sliding rheostat R1, a sliding rheostat R2, a sliding rheostat R3, a DC power supply, a relay RA, a relay RB, a relay RC, a positive power switching relay VA1, a positive power switching relay VB1, a positive power switching relay VC1, a negative power switching relay VA2, a negative power switching relay VB2, a negative power switching relay VC2, a first A / D conversion comparison module, a second A / D conversion comparison module, and a third A / D conversion comparison module.

[0030] The two ends of the voltage acquisition device V1 are connected between the wire clamp A and the wire clamp B, the two ends of the voltage acquisition device V2 are connected between the wire clamp B and the wire clamp C, the two ends of the voltage acquisition device V3 are connected between the wire clamp A and the wire clamp C, one end of the current acquisition device A1 is connected to the wire clamp A, and the other end of the current acquisition device A1 is connected to the fixed end of the sliding rheostat R1, one end of the current acquisition device A2 is connected to the wire clamp B, and the other end of the current acquisition device A2 is connected to the fixed end of the sliding rheostat R2, one end of the current acquisition device A3 is connected to the wire clamp C, and the other end of the current acquisition device A3 is connected to the fixed end of the sliding rheostat R3, one end of the relay RA is connected to the sliding rheostat R3 The sliding end of the relay RA is connected to the sliding end of the sliding rheostat R2, the other end of the relay RB is connected to the sliding end of the sliding rheostat R2, one end of the relay RC is connected between the relay RA and the relay RB, the other end of the relay RC is connected to the sliding end of the sliding rheostat R1, one end of the normally open contact of the positive power switching relay VA1, the positive power switching relay VB1, and the positive power switching relay VC1 is respectively connected to the sliding end of the sliding rheostat R1, the sliding rheostat R2, and the sliding rheostat R3, and the other end of the normally open contact of the positive power switching relay VA1, the positive power switching relay VB1, and the positive power switching relay VC1 is connected to the positive pole of the DC power supply. The sliding rheostat R1, the sliding rheostat R2, and the sliding rheostat R3 play a current limiting role. The voltage acquisition device and the current acquisition device can be implemented by using commonly used voltage transformers, current transformers, etc.

[0031] One end of the normally open contacts of the negative power switching relay VA2, the negative power switching relay VB2, and the negative power switching relay VC2 are respectively connected to the sliding ends of the sliding rheostat R1, the sliding rheostat R2, and the sliding rheostat R3, and the other ends of the normally open contacts of the negative power switching relay VA2, the negative power switching relay VB2, and the negative power switching relay VC2 are all connected to the negative pole of the DC power supply.

[0032] The voltage signal collected by the voltage acquisition device V1 and the current signal collected by the current acquisition device A1 are respectively input into the first A / D conversion comparison module, the voltage signal collected by the voltage acquisition device V2 and the current signal collected by the current acquisition device A2 are respectively input into the second A / D conversion comparison module, the voltage signal collected by the voltage acquisition device V3 and the current signal collected by the current acquisition device A are respectively input into the third A / D conversion comparison module, and the comparison result output ends of the first A / D conversion comparison module, the second A / D conversion comparison module and the third A / D conversion comparison module are connected to the data input end of the microcontroller. The internal structure of the first A / D conversion comparison module, the second A / D conversion comparison module and the third A / D conversion comparison module is: including an A / D converter and a comparator, the output end of the A / D converter is connected to the input end of the comparator, the comparison input end of the comparator inputs a comparison reference signal, and the output end of the comparator outputs the comparison result to the microcontroller. The A / D converter converts the analog voltage and current signals into digital quantities, and cooperates with the 74LS460 comparison chip to compare the collected digital quantities with the allowable error value, and compares them with the set allowable error value (such as 0.01V, 0.01A). If it is greater, the output result is 1, otherwise it outputs 0. The A / D conversion comparison module is used to determine whether there is a voltage or current signal.

[0033] The power input end of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC is powered, and the microcontroller outputs control signals to the control input ends of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC, respectively, to control the lighting and luminous colors of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC. The internal structure of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC is as follows: it includes a red-green bicolor light emitting diode, two current-limiting resistors, and two MOSFET tubes. The model of the red-green bicolor light emitting diode is LTST-C195KGJRKT. The bicolor light emitting diode can realize red, green, and red+green=yellow, and three-color luminescence. The anode of the red-green bicolor light emitting diode is connected to the positive pole of the power supply, and the two cathodes of the red-green bicolor light emitting diode are respectively connected in series with the current-limiting resistors configured respectively, and then respectively connected to the D pole of the MOSFET tube configured respectively, the S poles of the two MOSFET tubes are both grounded, and the G poles of the two MOSFET tubes are respectively connected to the control port of the microcontroller. The control end of the microcontroller outputs a signal to the G pole of the MOSFET tube that controls the corresponding red and green dual-color light-emitting diode according to the nuclear phase result, lighting the indicator light and displaying the corresponding color.

[0034] The master-slave switch K is connected to the microcontroller, and the master-slave switch K is used to set the master and slave states of the nuclear phase instrument before the distribution network is connected. The relay RA, relay RB, relay RC, positive power switching relay VA1, positive power switching relay VB1, positive power switching relay VC1, negative power switching relay VA2, negative power switching relay VB2, and negative power switching relay VC2 are each configured with a MOSFET tube, and one end of the relay RA coil, relay RB coil, relay RC coil, positive power switching relay VA1 coil, positive power switching relay VB1 coil, positive power switching relay VC1 coil, negative power switching relay VA2 coil, negative power switching relay VB2 coil, and negative power switching relay VC2 coil is connected to the power supply VCC, and the other ends of the relay RA coil, relay RB coil, relay RC coil, positive power switching relay VA1 coil, positive power switching relay VB1 coil, positive power switching relay VC1 coil, negative power switching relay VA2 coil, negative power switching relay VB2 coil, and negative power switching relay VC2 coil are respectively connected to the D pole of the MOSFET tube configured respectively, the S pole of each MOSFET tube is grounded, and the G pole of each MOSFET tube is respectively connected to the microcontroller. Relay RA, relay RB, and relay RC are used to short-circuit two phases during testing. For example, when the two phases AB are short-circuited, the coils of the two relays RA and RB are energized, and the normally open nodes of the two relays RA and RB are closed. The DC power supply is used to apply pressure and output pulse voltage during testing. The positive power switching relay VA1, the positive power switching relay VB1, the positive power switching relay VC1, the negative power switching relay VA2, the negative power switching relay VB2, and the negative power switching relay VC2 can apply pressure between the two phases according to different action combinations, and can change the direction of the voltage. For example, when the two phases AB are pressurized, the two relays VA1 and VB2 are energized, and the normally open nodes of the two relays VA1 and VB2 are closed. When applying voltage or applying pulse signals, they must not be applied at the same time, that is, to ensure that the DC voltage and the pulse voltage cannot exist at the same time. When a certain two phases are pressurized, except for the normally open nodes required for pressurization, other normally open nodes should be disconnected.

[0035] The method of using the phase check instrument before the distribution network connection includes the following steps: Figure 3As shown, two sets of phase detectors are used before the distribution network is connected, which are the host and the slave. The master's wire clamp A, wire clamp B, and wire clamp C are connected to the three phases A, B, and C of the fixed phase sequence end respectively. The slave measures at the other end of the line. The slave's wire clamp A, wire clamp B, and wire clamp C are connected to the line end of the unknown phase sequence at the measuring end. The principle of the slave identification program is: if the two phases on the host side are short-circuited, if the voltage is added to the same two phases on the slave side, the existence of current can be detected in the circuit of these two phases, and the phase that cannot be detected is the same phase line as the phase that is not short-circuited on the host side. Complete three phase-to-phase (AC phase, AB phase, BC phase) inspections, and then define the phase that does not appear in the three inspections as the phase without current. As the output result, light up the corresponding light bulb and the color of the phase. The slave machine's color-changing indicator light module LA, color-changing indicator light module LB, and color-changing indicator light module LC display yellow, green, and red according to the phase verification results. Yellow represents phase A, green represents phase B, and red represents phase C. Phases A, B, and C are determined based on the displayed colors, and the phase verification is completed.

[0036] like Figure 4 As shown in the figure, the specific working process is as follows: After the host and the slave are turned on, the host lights up the three yellow, green and red light bulbs, and the slave clears the number N. The host short-circuits the BC phases, and the slave starts the discrimination program. After the discrimination program is completed, the slave lights up the yellow light of the phase without flow, and then the slave side applies a pulse voltage between the phase with flow and the phase without flow for 5 seconds. After 5 seconds, the slave enters the next discrimination program. After the host receives the pulse signal, it disconnects the current short-circuit connection and changes to short-circuit the AC phases. After the slave discrimination program is completed, the slave lights up the green light of the phase without flow, and then the slave side applies a pulse voltage between the phase with flow and the phase without flow for 5 seconds. After 5 seconds, the slave enters the next discrimination program. After the host receives the pulse signal, it disconnects the current short-circuit connection and changes to short-circuit the AB phases. After the slave discrimination program is completed, the slave lights up the red light of the phase without flow, and then the slave side applies a pulse voltage between the phase with flow and the phase without flow for 5 seconds. After 5 seconds, the slave ends the program. After the host receives the pulse signal, it ends the host program. The result can be determined only when there is current in the two phases of the pressurization during one and only one of the three pressurization processes. Otherwise, the program is judged to be an error and the process is terminated.

[0037] In order to prevent the master from turning on after the slave, and causing a program error due to failure to detect current, the slave is set to count times N to control, requiring the judgment program to start counting after the slave detects the current. Only when the current is detected can N+1 be added, and the number N can be increased. Only when N=1 is the result of the investigation valid, otherwise it is invalid and not adopted by the system. After completing the three phase-to-phase (AC phase, AB phase, BC phase) investigation, the phase that did not appear in the three investigations is allowed to be defined as the phase without current, as the output result, and the corresponding light bulb and color are lit.

[0038] The principle of the slave identification program is: when the two phases on the host side are short-circuited, when the voltage is added to the corresponding two phases on the slave side, the existence of current can be detected in the circuits of these two phases, and the phase that cannot be detected is the same phase line as the phase that is not short-circuited on the host side.

[0039] like Figure 5 As shown, the slave identification method is: when the host short-circuits two phases, the slave applies voltage between phases AB, between phases BC, and between phases AC in turn to detect whether there is current in phases A, B, and C. The sequence is checked three times. The phase without current means that the host is not short-circuited. The slave lights up the color-changing indicator light module corresponding to the wire clamp connected to the phase and displays the corresponding color. Phase A corresponds to yellow, phase B corresponds to green, and phase C corresponds to red.

[0040] In order to avoid the situation where N is not 1 due to the influence of detection errors, a count S is set. Only after three rounds of pressurization with abnormal results (N is not 1) can S+1 be achieved. When S=3, three rounds of effective investigations have been completed, and the results are all abnormal. An alarm signal is reported and the program is terminated.

[0041] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A phase check instrument before the distribution network is spliced, characterized in that: It includes a microcontroller, a wire clamp A, a wire clamp B, a wire clamp C, a color-changing indicator light module LA, a color-changing indicator light module LB, a color-changing indicator light module LC, a master-slave switching switch K, a voltage acquisition device V1, a voltage acquisition device V2, a voltage acquisition device V3, a current acquisition device A1, a current acquisition device A2, a current acquisition device A3, a sliding rheostat R1, a sliding rheostat R2, a sliding rheostat R3, a DC power supply, a relay RA, a relay RB, a relay RC, a positive power switching relay VA1, a positive power switching relay VB1, a positive power switching relay VC1, a negative power switching relay VA2, and a negative power switching relay V B2, negative power switching relay VC2, a first A / D conversion comparison module, a second A / D conversion comparison module, and a third A / D conversion comparison module; the two ends of the voltage acquisition device V1 are connected between the wire clamp A and the wire clamp B, the two ends of the voltage acquisition device V2 are connected between the wire clamp B and the wire clamp C, the two ends of the voltage acquisition device V3 are connected between the wire clamp A and the wire clamp C, one end of the current acquisition device A1 is connected to the wire clamp A, and the other end of the current acquisition device A1 is connected to the fixed end of the sliding rheostat R1, one end of the current acquisition device A2 is connected to the wire clamp B, and the other end of the current acquisition device A2 is connected to the fixed end of the sliding rheostat R2 One end of the current collection device A3 is connected to the wire clamp C, and the other end of the current collection device A3 is connected to the fixed end of the sliding rheostat R3. One end of the relay RA is connected to the sliding end of the sliding rheostat R3, and the other end of the relay RA is connected to one end of the relay RB, and the other end of the relay RB is connected to the sliding end of the sliding rheostat R2. One end of the relay RC is connected between the relay RA and the relay RB, and the other end of the relay RC is connected to the sliding end of the sliding rheostat R1. One end of the normally open contact of the positive power switching relay VA1, the positive power switching relay VB1, and the positive power switching relay VC1 is respectively connected to the sliding rheostat The sliding ends of the sliding rheostats R1, R2 and R3 are connected, and the other ends of the normally open contacts of the positive power switching relays VA1, VB1 and VC1 are all connected to the positive electrode of the DC power supply; one end of the normally open contacts of the negative power switching relays VA2, VB2 and VC2 are respectively connected to the sliding ends of the sliding rheostats R1, R2 and R3, and the other ends of the normally open contacts of the negative power switching relays VA2, VB2 and VC2 are all connected to the negative electrode of the DC power supply;The voltage signal collected by the voltage acquisition device V1 and the current signal collected by the current acquisition device A1 are respectively input into the first A / D conversion comparison module, the voltage signal collected by the voltage acquisition device V2 and the current signal collected by the current acquisition device A2 are respectively input into the second A / D conversion comparison module, the voltage signal collected by the voltage acquisition device V3 and the current signal collected by the current acquisition device A are respectively input into the third A / D conversion comparison module, and the comparison result output ends of the first A / D conversion comparison module, the second A / D conversion comparison module and the third A / D conversion comparison module are connected to the data input end of the microcontroller; the power input end of the color-changing indicator light module LA, the color-changing indicator light module LB and the color-changing indicator light module LC is supplied with power, and the microcontroller outputs control signals to the control input ends of the color-changing indicator light module LA, the color-changing indicator light module LB and the color-changing indicator light module LC respectively to control the lighting and luminous color of the color-changing indicator light module LA, the color-changing indicator light module LB and the color-changing indicator light module LC; the master-slave switch K is connected to the microcontroller, and the relays RA, RB and RC are connected to the microcontroller. , the positive power switching relay VA1, the positive power switching relay VB1, the positive power switching relay VC1, the negative power switching relay VA2, the negative power switching relay VB2, and the negative power switching relay VC2 are each configured with a MOSFET tube, one end of the relay RA coil, the relay RB coil, the relay RC coil, the positive power switching relay VA1 coil, the positive power switching relay VB1 coil, the positive power switching relay VC1 coil, the negative power switching relay VA2 coil, the negative power switching relay VB2 coil, and the negative power switching relay VC2 coil is connected to the power supply VCC, and the other ends of the relay RA coil, the relay RB coil, the relay RC coil, the positive power switching relay VA1 coil, the positive power switching relay VB1 coil, the positive power switching relay VC1 coil, the negative power switching relay VA2 coil, the negative power switching relay VB2 coil, and the negative power switching relay VC2 coil are respectively connected to the D pole of the MOSFET tube configured respectively, the S pole of each MOSFET tube is grounded, and the G pole of each MOSFET tube is respectively connected to the microcontroller; The internal structures of the color-changing indicator light module LA, the color-changing indicator light module LB, and the color-changing indicator light module LC are as follows: comprising a red-green dual-color light emitting diode, two current-limiting resistors, and two MOSFET tubes, the model of the red-green dual-color light emitting diode is LTST-C195KGJRKT, the anode of the red-green dual-color light emitting diode is connected to the positive electrode of the power supply, the two cathodes of the red-green dual-color light emitting diodes are respectively connected in series with the current-limiting resistors respectively configured, and then respectively connected to the D poles of the MOSFET tubes respectively configured, the S poles of the two MOSFET tubes are both grounded, and the G poles of the two MOSFET tubes are respectively connected to the control ports of the microcontroller; The internal structure of the first A / D conversion comparison module, the second A / D conversion comparison module, and the third A / D conversion comparison module is: including an A / D converter and a comparator, the output end of the A / D converter is connected to the input end of the comparator, the comparison input end of the comparator inputs a comparison reference signal, and the output end of the comparator outputs a comparison result to the microcontroller.

2. A phase checking method of the phase checking instrument before the distribution network overlap as claimed in claim 1, characterized in that The following steps are involved: The wire clamps A, B and C of the host are connected to the three phases A, B and C of the fixed phase sequence end respectively. After the host and the slave are turned on, the color-changing indicator light LA ​​module, the color-changing indicator light LB module and the color-changing indicator light LC module of the host are respectively lit in yellow, green and red; the host side short-circuits the two phases B and C, and the slave starts the discrimination program. After the discrimination program is completed, the slave lights the color-changing indicator light module of the phase without current to yellow, and then the slave side applies a pulse voltage between the phase with current and the phase without current for n seconds. After n seconds, the slave enters the next discrimination program; After receiving the pulse voltage signal, the host disconnects the short-circuit connection between phases B and C and short-circuits phases A and C instead. The slave starts the discrimination procedure. After the discrimination procedure is completed, the slave lights up the color-changing indicator light module of the phase without current to green. Then, the slave adds a pulse voltage signal between the phase with current and the phase without current for n seconds. After n seconds, the slave enters the next discrimination procedure. After the host receives the pulse voltage signal, it disconnects the short-circuit connection between phases A and C and changes to short-circuit phases A and B. The slave starts the identification program. After the slave identification program ends, the slave lights up the color-changing indicator light module of the phase without current to red. Then the slave side applies a pulse voltage between the phase with current and the phase without current for n seconds. After n seconds, the slave ends the program. After the host receives the pulse voltage signal, it ends the program. The slave identification method is as follows: when the host short-circuits two phases, the slave applies voltage between phases AB, between phases BC, and between phases AC in turn to detect whether there is current in phases A, B, and C. The sequence is checked three times. The phase without current means that the host has not short-circuited the phase. The slave lights up the color-changing indicator light module corresponding to the wire clamp connected to the phase and displays the corresponding color. A corresponds to yellow, B corresponds to green, and C corresponds to red.

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