CN206657049U - Power transformer iron core grounding current sample circuit - Google Patents

Power transformer iron core grounding current sample circuit Download PDF

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Publication number
CN206657049U
CN206657049U CN201720453460.9U CN201720453460U CN206657049U CN 206657049 U CN206657049 U CN 206657049U CN 201720453460 U CN201720453460 U CN 201720453460U CN 206657049 U CN206657049 U CN 206657049U
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China
Prior art keywords
pin
resistance
current
transformer
slide rheostat
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Expired - Fee Related
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CN201720453460.9U
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Chinese (zh)
Inventor
李双厚
陈继民
齐国顺
姜佰锋
林波
郭士昌
李冰
苏业超
江学琴
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
State Grid Corp of China SGCC
State Grid Heilongjiang Electric Power Co Ltd
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State Grid Corp of China SGCC
State Grid Heilongjiang Electric Power Co Ltd
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Priority to CN201720453460.9U priority Critical patent/CN206657049U/en
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Publication of CN206657049U publication Critical patent/CN206657049U/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Abstract

Power transformer iron core grounding current sample circuit, belongs to power supply field, and the utility model is to solve the problems, such as that existing transformer core current cailure rate of false positives is high.The utility model:Transformer T secondary side is load output voltage by mu balanced circuit, and sample circuit includes current transformer TA, LA25NP current sensor, amplifier A1, NE555 time-base integrated circuit, auxiliary reclay KA, 7805 voltage stabilizing chips, rectifier bridge, resistance R1~R7, slide rheostat Rp1, slide rheostat Rp2, electric capacity C1~C4 and voltage-stabiliser tube Vs;Series connection auxiliary reclay KA normally-closed contacts in the exchange output loop of mu balanced circuit;Earth fault occurs for transformer core, and its earth current increases severely, and the KA normally-closed contacts for being connected on mu balanced circuit outlet side disconnect, and cut off the loop to secondary side load supplying, are just restored electricity after power circuit is normal.

Description

Power transformer iron core grounding current sample circuit
Technical field
The utility model belongs to power supply field.
Background technology
When multipoint earthing of iron core failure occurs for transformer, iron core grounding current can uprush, on transformer core grounding line Transformer iron core grounding current on-line monitoring equipment is installed, the earth current of transformer core is monitored in real time, is monitoring The effective ways of multipoint earthing of iron core.
It is inaccurate due to sampling output result when sample rate current is excessive in actual motion, and then cause equipment rate of false alarm It is high.
The content of the invention
The purpose of the utility model is to solve the problems, such as that existing transformer core current cailure rate of false positives is high, there is provided one Kind power transformer iron core grounding current sample circuit.
Power transformer iron core grounding current sample circuit described in the utility model, transformer T secondary side pass through voltage stabilizing Circuit is load output voltage, and sample circuit includes base when current transformer TA, LA25NP current sensor, amplifier A1, NE555 Integrated circuit, auxiliary reclay KA, 7805 voltage stabilizing chips, rectifier bridge, resistance R1~R7, slide rheostat Rp1, slide rheostat Rp2, electric capacity C1, electric capacity C2, electrochemical capacitor C3, electrochemical capacitor C4 and voltage-stabiliser tube Vs;
Series connection auxiliary reclay KA normally-closed contacts in the exchange output loop of mu balanced circuit;
Current transformer TA primary coil string is on transformer T iron core, current transformer TA secondary coil difference 5 pin and 6 pin of LA25NP current sensors are connected, 3 pin of LA25NP current sensors connect+15V dc sources, LA25NP electric currents 2 pin of sensor connect -15V dc sources, and 1 pin of LA25NP current sensors is grounded,
The 4 pin connection amplifier A1 of LA25NP current sensors in-phase input end, amplifier A1 in-phase input end pass through electricity Hinder R1 ground connection;Amplifier A1 inverting input is grounded by resistance R2, in parallel between amplifier A1 inverting input and output end One ac input end of resistance R3, amplifier A1 output end connection rectifier bridge, another ac input end ground connection of rectifier bridge;
The cathode power supply output end of rectifier bridge connects electric capacity C1 one end, resistance R4 one end and 7805 voltage stabilizing chips simultaneously 1 pin, the negative power supply output end of rectifier bridge connects the electric capacity C1 other end, the resistance R4 other end and 7805 voltage stabilizing cores simultaneously 2 pin of piece, and be grounded;The 3 pin connection slide rheostat Rp1 of a 7805 voltage stabilizing chips fixing end;Slide rheostat Rp1's Sliding end connects electrochemical capacitor C3 positive pole and 2 pin of NE555 time-base integrated circuits simultaneously;
1 pin of NE555 time-base integrated circuits connects electric capacity C2 one end and electrochemical capacitor C3 negative pole simultaneously;
5 pin of NE555 time-base integrated circuits connect voltage-stabiliser tube Vs anode, electrochemical capacitor C4 negative pole and slided simultaneously to be become A device Rp2 fixing end is hindered, and is grounded;Slide rheostat Rp2 another fixing end and slide rheostat Rp1 another Fixing end is connected;
The 4 pin connection slide rheostat Rp2 of NE555 time-base integrated circuits sliding end;
The 6 pin connection resistance R7 of NE555 time-base integrated circuits one end;
8 pin of NE555 time-base integrated circuits connect electrochemical capacitor C4 positive pole, the resistance R7 other end, resistance R6 simultaneously One end and resistance R5 one end;Resistance R6 other end connection voltage-stabiliser tube Vs negative electrode;
NE555 time-base integrated circuits 3 pin connection auxiliary reclay KA coils one end, auxiliary reclay KA coils it is another One end connection resistance R5 other end.
Preferably, the single-phase full bridge rectification circuit that rectifier bridge is made up of diode D1~D4.
The advantages of the utility model:Power transformer iron core grounding current sample circuit described in the utility model is applied to big Current sample, it is simple in construction, reliable working performance, effectively reduce rate of false alarm.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams of power transformer iron core grounding current sample circuit described in the utility model.
Embodiment
Embodiment one:Illustrate present embodiment, electrical transformer cores described in present embodiment with reference to Fig. 1 Earth current sample circuit, transformer T secondary side are load output voltage by mu balanced circuit, and it is mutual that sample circuit includes electric current It is sensor TA, LA25NP current sensor, amplifier A1, NE555 time-base integrated circuit, auxiliary reclay KA, 7805 voltage stabilizing chips, whole Flow bridge, resistance R1~R7, slide rheostat Rp1, slide rheostat Rp2, electric capacity C1, electric capacity C2, electrochemical capacitor C3, electrochemical capacitor C4 and voltage-stabiliser tube Vs;
Series connection auxiliary reclay KA normally-closed contacts in the exchange output loop of mu balanced circuit;
Current transformer TA primary coil string is on transformer T iron core, current transformer TA secondary coil difference 5 pin and 6 pin of LA25NP current sensors are connected, 3 pin of LA25NP current sensors connect+15V dc sources, LA25NP electric currents 2 pin of sensor connect -15V dc sources, and 1 pin of LA25NP current sensors is grounded,
The 4 pin connection amplifier A1 of LA25NP current sensors in-phase input end, amplifier A1 in-phase input end pass through electricity Hinder R1 ground connection;Amplifier A1 inverting input is grounded by resistance R2, in parallel between amplifier A1 inverting input and output end One ac input end of resistance R3, amplifier A1 output end connection rectifier bridge, another ac input end ground connection of rectifier bridge;
The cathode power supply output end of rectifier bridge connects electric capacity C1 one end, resistance R4 one end and 7805 voltage stabilizing chips simultaneously 1 pin, the negative power supply output end of rectifier bridge connects the electric capacity C1 other end, the resistance R4 other end and 7805 voltage stabilizing cores simultaneously 2 pin of piece, and be grounded;The 3 pin connection slide rheostat Rp1 of a 7805 voltage stabilizing chips fixing end;Slide rheostat Rp1's Sliding end connects electrochemical capacitor C3 positive pole and 2 pin of NE555 time-base integrated circuits simultaneously;
1 pin of NE555 time-base integrated circuits connects electric capacity C2 one end and electrochemical capacitor C3 negative pole simultaneously;
5 pin of NE555 time-base integrated circuits connect voltage-stabiliser tube Vs anode, electrochemical capacitor C4 negative pole and slided simultaneously to be become A device Rp2 fixing end is hindered, and is grounded;Slide rheostat Rp2 another fixing end and slide rheostat Rp1 another Fixing end is connected;
The 4 pin connection slide rheostat Rp2 of NE555 time-base integrated circuits sliding end;
The 6 pin connection resistance R7 of NE555 time-base integrated circuits one end;
8 pin of NE555 time-base integrated circuits connect electrochemical capacitor C4 positive pole, the resistance R7 other end, resistance R6 simultaneously One end and resistance R5 one end;Resistance R6 other end connection voltage-stabiliser tube Vs negative electrode;
NE555 time-base integrated circuits 3 pin connection auxiliary reclay KA coils one end, auxiliary reclay KA coils it is another One end connection resistance R5 other end.
The single-phase full bridge rectification circuit that rectifier bridge is made up of diode D1~D4.
Operation principle:
Transformer T primary coil connects AC power, and the break-make of AC power is controlled by circuit breaker Q S.Transformer secondary line The alternating current of output is enclosed by being load output power supply after mu balanced circuit, the break-make of the working power is by auxiliary reclay KA Normally-closed contact controls.
Earth current on current transformer TA sensor transformer T iron cores, when the no ground failure of transformer T iron core, its Earth current is typically within 0.5A, and LA25NP gathers the current output voltage signal, and is amplified by amplifier A1 and exported, the friendship It is direct current to flow voltage signal rectification, then is exported by 7805 voltage stabilizings, then by Rp1 partial pressures, 2 pin of the magnitude of voltage exported to NE555, NE555 and periphery electronic component form RS triggering mode of operations, due to voltage-stabiliser tube Vs1 access so that NE555 internal comparators Reference voltage clamp voltage be about 4V or so.The sampling value that transfinites accesses NE555 2 pin from Rp1 movable end, when ground connection electricity Flowing small (being less than 0.5A), NE555 2 pin input voltages are less than 2V, and sampling voltage is higher than 0.7V resetting voltage value on 4 pin, Overturn inside so NE555, its 3 pin output high level, KA coils both ends are high voltage, and KA coils must not be electric, and it is connected on The normally-closed contact of mu balanced circuit outlet side is kept closed, and transformer exports burning voltage to secondary lateral load.Now power Normally.
If earth fault occurs for transformer core, its earth current increases severely, and current transformer TA senses high current, The current value that LA25NP is collected is big, and the magnitude of voltage of output is also big, and NE555 resets, and its 3 pin changes into low level, KA from high level There is voltage difference in coil both ends, KA coils obtain electric, and it is connected on the normally-closed contact of mu balanced circuit outlet side and disconnected, and cuts off to secondary The loop of lateral load power supply, just restores electricity after power circuit is normal.

Claims (2)

1. power transformer iron core grounding current sample circuit, transformer T secondary side is electric for load output by mu balanced circuit Pressure, it is characterised in that sample circuit include current transformer TA, LA25NP current sensor, amplifier A1, NE555 when basis set into Circuit, auxiliary reclay KA, 7805 voltage stabilizing chips, rectifier bridge, resistance R1~R7, slide rheostat Rp1, slide rheostat Rp2, Electric capacity C1, electric capacity C2, electrochemical capacitor C3, electrochemical capacitor C4 and voltage-stabiliser tube Vs;
Series connection auxiliary reclay KA normally-closed contacts in the exchange output loop of mu balanced circuit;
On transformer T iron core, current transformer TA secondary coil connects current transformer TA primary coil string respectively 5 pin and 6 pin of LA25NP current sensors, 3 pin of LA25NP current sensors connect+15V dc sources, LA25NP current senses 2 pin of device connect -15V dc sources, and 1 pin of LA25NP current sensors is grounded,
The 4 pin connection amplifier A1 of LA25NP current sensors in-phase input end, amplifier A1 in-phase input end pass through resistance R1 Ground connection;Amplifier A1 inverting input is grounded by resistance R2, parallel resistance between amplifier A1 inverting input and output end One ac input end of R3, amplifier A1 output end connection rectifier bridge, another ac input end ground connection of rectifier bridge;
The cathode power supply output end of rectifier bridge connects the 1 of electric capacity C1 one end, resistance R4 one end and 7805 voltage stabilizing chips simultaneously Pin, the negative power supply output end of rectifier bridge connect the electric capacity C1 other end, the resistance R4 other end and 7805 voltage stabilizing chips simultaneously 2 pin, and be grounded;The 3 pin connection slide rheostat Rp1 of a 7805 voltage stabilizing chips fixing end;Slide rheostat Rp1 cunning Moved end connects electrochemical capacitor C3 positive pole and 2 pin of NE555 time-base integrated circuits simultaneously;
1 pin of NE555 time-base integrated circuits connects electric capacity C2 one end and electrochemical capacitor C3 negative pole simultaneously;
5 pin of NE555 time-base integrated circuits connect voltage-stabiliser tube Vs anode, electrochemical capacitor C4 negative pole and slide rheostat simultaneously A Rp2 fixing end, and be grounded;Another of slide rheostat Rp2 another fixing end and slide rheostat Rp1 are fixed End is connected;
The 4 pin connection slide rheostat Rp2 of NE555 time-base integrated circuits sliding end;
The 6 pin connection resistance R7 of NE555 time-base integrated circuits one end;
8 pin of NE555 time-base integrated circuits connect electrochemical capacitor C4 positive pole, the resistance R7 other end, the one of resistance R6 simultaneously End and resistance R5 one end;Resistance R6 other end connection voltage-stabiliser tube Vs negative electrode;
One end of the 3 pin connection auxiliary reclay KA coils of NE555 time-base integrated circuits, the other end of auxiliary reclay KA coils Connect the resistance R5 other end.
2. power transformer iron core grounding current sample circuit according to claim 1, it is characterised in that rectifier bridge is by two The single-phase full bridge rectification circuit that pole pipe D1~D4 is formed.
CN201720453460.9U 2017-04-26 2017-04-26 Power transformer iron core grounding current sample circuit Expired - Fee Related CN206657049U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201720453460.9U CN206657049U (en) 2017-04-26 2017-04-26 Power transformer iron core grounding current sample circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201720453460.9U CN206657049U (en) 2017-04-26 2017-04-26 Power transformer iron core grounding current sample circuit

Publications (1)

Publication Number Publication Date
CN206657049U true CN206657049U (en) 2017-11-21

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CN201720453460.9U Expired - Fee Related CN206657049U (en) 2017-04-26 2017-04-26 Power transformer iron core grounding current sample circuit

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108879967A (en) * 2018-09-19 2018-11-23 广东电网有限责任公司 A kind of power distribution station outlet branch line switch trip warning system
CN108900009A (en) * 2018-09-19 2018-11-27 广东电网有限责任公司 A kind of power distribution station outlet branch line switch trip alarm device
CN109560526A (en) * 2018-09-19 2019-04-02 广东电网有限责任公司 A kind of power distribution station outlet branch line switching current alarm device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108879967A (en) * 2018-09-19 2018-11-23 广东电网有限责任公司 A kind of power distribution station outlet branch line switch trip warning system
CN108900009A (en) * 2018-09-19 2018-11-27 广东电网有限责任公司 A kind of power distribution station outlet branch line switch trip alarm device
CN109560526A (en) * 2018-09-19 2019-04-02 广东电网有限责任公司 A kind of power distribution station outlet branch line switching current alarm device

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CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20171121

Termination date: 20180426

CF01 Termination of patent right due to non-payment of annual fee