CN1331289C

CN1331289C - Overcurrent electronic protector for electric appliance

Info

Publication number: CN1331289C
Application number: CNB01107244XA
Authority: CN
Inventors: 李相明
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-13
Filing date: 2001-03-13
Publication date: 2007-08-08
Anticipated expiration: 2021-03-13
Also published as: CN1374726A

Abstract

An overcurrent electronic protector for electric appliances is composed of a voltage-stabilized power supply circuit, an alternating current dynamic detection circuit, a proportional amplification circuit, an inverse time delay circuit, a short-circuit protection circuit, a trip circuit, a large-current action time acceleration circuit and a protection action index stabilizing circuit; the accelerating circuit and the stabilizing circuit mainly solve the problems of high current and protection stability; the motor protection circuit establishes a continuous change relation between current and action time, has good inverse time limit protection characteristic, has high stability, and can realize all-round and reliable protection on various dynamic parameters of the motor.

Description

Electrical equipment overcurrent electronic protector

Technical field

The present invention relates to a kind of generating, distribution and electromechanical equipment overcurrent protective device, make the field in particular for the electronic type overcurrent protective device of motor.

Background technology

As everyone knows, the mechanical type overcurrent protective device is subjected to influence of temperature change as bimetal leaf overcurrent protection product, and sensitivity is lower, and to electromechanical equipment, particularly motor can not provide effective protection.The electron type overcurrent protection is not subjected to influence of temperature change; highly sensitive; but; because it is big (as mains voltage variations influenced by change in voltage; the line current fluctuation all causes the variation that detects voltage; especially for motor; also to be subjected to the different variations that cause detection voltage of electric motor starting, control, running status and mechanical property); thereby stability and reliability are electronic type overcurrent product a great problems anxious to be solved; particularly the electric motor protecting technical difficulty is bigger: 1, want cube little, be convenient to install.2, require cost low, motor itself is cheap.3, protection fault current wide ranges; as overload current scope 1.2～10Ie, claiming overload to be meant overload 1.2Ie traditionally; motor seize overload current scope 1.2～7Ie; stall overload current scope 6～7Ie; it is 7Ie at two utmost points, four utmost point motors, and 6-pole motor is 6.5Ie, and ends of the earth motor is 6Ie; motor was in and creeps or stall when under-voltage, overload current scope 2～7Ie, voltage reached and drop to 300V by 380V.4, electric motor protecting relates to a lot of functions of use; (be mainly used in the following motor of 10KW as (1) direct-on-line starting; the 7.5KW that has just adopts reduced voltage starting); (2) reduced voltage starting (generally adopts the starting of Y shape; the operation of △ shape) its feature is that starting current is arranged twice; because starting current is exactly a locked rotor current, function of use and defencive function are various to be the key technology difficult problem of motor protecter.(3) steady load and swinging load (ordinary circumstance: the steady load motor leaves the surplus of 20-30%, and the swinging load motor leaves 50% surplus when equipment is unloaded) are arranged.In addition, the motor rotation blockage electric current is relevant with motor pole number, has more increased design difficulty.At present, the home and abroad corresponding product all exists poor stability, problem that reliability is low, and comparatively desirable all-round protection product also occurs.The external existing problem of electronic type overcurrent protection product is: 1, the protective feature index of German AEG company " ME series frame circuit breaker " is: 0.5-10Ie (rated current), and operate time is the longest 30 seconds, is used for the easy misoperation of motor; 2-12Ie is the shortest 3 seconds, and is the longest 27 seconds, can not be used for the blower fan reduced voltage starting; 2, the problem and the defective of the protective feature index of Siemens " 3WN6 series frame-type circuit breaker " are: its just action of long delay overload 40%; regularly 10 seconds; in order to reduce misoperation; setting air switch 1.05Ie is failure to actuate; change the 1.4Ie action into; protection range has been dwindled, do not meet the properties of product requirement.Its 40 seconds is to be the setting of blower fan reduced voltage starting, does not meet the requirement of thermal relay stall＜10 second.Above-mentioned external product exists: 1, poor stability is used for motor and particularly manifests.Therefore Siemens 3WN6 series orders initial value for 1.4Ie just moves, the setting current fixed point, and fixed point can remedy the deficiency of poor stability, but can not fundamentally solve stability problem operate time; 2, protective feature curve (statement independent variable: prospective current/release rated current and dependent variable: be trapezoidal the functional relation between operate time); curve is imperfect; there is neutral gear the centre; in the domestic similar products; Sichuan Meishan Pu Da company " motor protecting switch "; Yanshi, Henan low-voltage electrical apparatus factory " protection motor plug-in strip ", Chengdu, Sichuan 432 mailbox " multi-functional electric motor protecting consumer unit " are the purposes that the restriction scope of application (direct-on-line starting) reaches use.Its rotation-clogging protection index is all defective; Products such as Jinan, Shandong is this, bright strong, Chengdu 432 mailbox of Ningbo of Zhejiang giant dragon, Xianyang, Nanjing are all established a point protection, and starting time-delay design is arranged, and promptly starting process is not protected, and it does not meet the requirement of thermal relay properties of product.It is many that protector protection point is just being deposited in Beijing; but consistency is very poor, differs more than 3 times as 6Ie about 3～15 seconds, still can not protect stall; above product lacks complete protective feature curve; do not possess protection action index consistency, can only use according to the specific scope of application adjustment of user, simultaneously; less stable; because of mains fluctuations, motor oscillating, motor load changes, and all easily makes protector produce misoperation.In addition; Chinese patent literature discloses " the all-round protector of excessive current flow in motor " (CN2218421Y); be made up of power circuit, the dynamic testing circuit of alternating current, ratio amplifying circuit, inverse time-lag circuit and short-circuit protection circuit, major defect is a deficient in stability.

Summary of the invention

Task of the present invention is at above prior art problems and weak point and a kind of electrical equipment overcurrent electronic protector is provided that it has the integrality of high stability and protective feature curve.

Task of the present invention realizes by following design: a kind of electrical equipment overcurrent electronic protector, comprise voltage-stabilized power supply circuit, the dynamic testing circuit 1 of alternating current, 1.2Ie ratio amplifying circuit 2, inverse time-lag circuit 5, short-circuit protection circuit 6, trip circuit 7, the dynamic testing circuit 1 of above-mentioned alternating current, 1.2Ie ratio amplifying circuit 2, inverse time-lag circuit 5, short-circuit protection circuit 6, trip circuit 7 cascade in turn; The dynamic testing circuit 1 of above-mentioned alternating current, short-circuit protection circuit 6, trip circuit 7 cascade in turn is characterized in that, also comprise:

A), big electric current accelerating circuit operate time 3: form by operational amplifier A the 2, the 19 resistance R the 19, the 20 resistance R the 20, the 21 resistance R the 21, the 22 resistance R 22; The negative input end of operational amplifier (A2) is connected after the 19 resistance R 19, be connected to the output of the dynamic testing circuit 1 of described alternating current, the positive input terminal of operational amplifier A 2 is connected and is connected to an end of the 21 resistance R the 21, the 22 resistance R 22 after the 20 resistance R 20 respectively, the described voltage-stabilized power supply circuit cathode output end of the 21 resistance R 21 another terminations, the 22 resistance R 22 other end ground connection;

B), protection action index stabilizing circuit 4: be made up of the 7th diode D7, the 8th diode D8, the tenth diode D10, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7, the tenth resistance R the 10, the 12 resistance R the 12, the 13 resistance R 13; After the tenth the anodal series connection of diode D10 the 12 resistance R 12, the output that is connected to above-mentioned big electric current accelerating circuit operate time 3 is the output of operational amplifier A 2, the tenth diode D10 negative pole and the 7th diode D7 positive pole all are connected to the input of described inverse time-lag circuit 5, the 7th diode D7 negative pole the 6th resistance R 6 in sequential series, the 7th resistance R 7 back ground connection, the 13 resistance R 13 1 is terminated at the interface point of the 6th resistance R 6 and the 7th resistance R 7, the cathode output end of the described voltage-stabilized power supply circuit of the 13 resistance R 13 another terminations, the 8th diode D8 negative pole is connected to the 7th diode D7 negative pole, after the 8th the anodal series connection of diode D8 the tenth resistance R 10, be connected to the output of 1.2Ie ratio amplifying circuit 2.

Above-mentioned design is the common problem at existing electronic overcurrent protection product, on original patent (CN2218421Y) basis, sets up big electric current accelerating circuit operate time and protection action index stabilizing circuit.It has solved stability and protective feature curve integrity issue (seeing circuit theory for details sets forth) effectively.

Description of drawings

Fig. 1 Fig. 2 is respectively circuit diagram of the present invention and electric theory diagram;

Fig. 3 is the protective feature curve chart of one embodiment of the invention.

Embodiment

Fig. 1 Fig. 2 illustrates, and the present invention is by stabilized power supply circuit, the dynamic testing circuit 1 of alternating current (abbreviation testing circuit).1.2Ie ratio amplifying circuit 2 (abbreviation amplifying circuit), big electric current accelerating circuit operate time 3 (abbreviation accelerating circuit), protection action index stabilizing circuit 4 (abbreviation stabilizing circuits), inverse time-lag circuit 5 (abbreviation delay circuit), short-circuit protection circuit 6, trip circuit 7 are formed; Foregoing circuit 1,2,4,5,6,7 cascades in turn (upper level output connects the next stage input); Circuit 1,6,7 cascades in turn.Accelerating circuit 3 is made up of operational amplifier A 2, resistance R 19, R20, R21, R22; Behind the negative input end series connection R19 of operational amplifier A 2, be connected to the output of testing circuit 1, be connected to the end of R21, R22 behind the positive input terminal series connection R20 of A2 respectively, the described voltage-stabilized power supply circuit cathode output end of another termination of R21, R22 other end ground connection; The voltages that the positive input terminal of operational amplifier A 2 inserts by resistance R 20 back are locked-rotor voltage to motor, to generating, voltage when power distribution protection is decided to be 2Ie.Light-emitting diode D12, D13 aim at the blower fan reduced voltage starting and establish, when Y shape is started, light-emitting diode D13 just goes out, D12 is just bright, reach to this levels of precision very difficult, can utilize this moment blower fan Y shape starting time length and starting current not to return zero characteristics, change resistance R 21 and R22 into potentiometer, adjust, can avoid the frame-type circuit breaker multiple spot to be provided with and the underproof disadvantage of motor protecter rotation-clogging protection index by the scene; Stabilizing circuit 4 is made up of diode D7, D8, D10, resistance R 5, R6, R7, R10, R12, R13; Behind the anodal series connection of the D10 R12, the output that is connected to accelerating circuit 3 is the output of operational amplifier A 2, D10 negative pole and D7 positive pole all are connected to the input of delay circuit 5, D7 negative pole R6 in sequential series, ground connection behind the R7, R13 one is terminated at the interface point of R6 and R7, the cathode output end of the described voltage-stabilized power supply circuit of another termination of R13, the D8 negative pole is connected to the D7 negative pole, behind the anodal series connection of the D8 R10, be connected to the output of amplifying circuit 2, at diode D7, D8, insert voltage-V8 by resistance R 6 on the node of resistance R 5, when the motor normal starting entered normal operating condition, voltage-V8 was again the discharge voltage of delay capacitor C5, because-V8 is a steady state value, it is constant that discharge capacity keeps, wherein diode D8, D10 is an isolating diode, thereby has realized protection action index consistency and repeatability; Stabilized power supply circuit is by transformer T, and diode D1-D4, C1, C2 and positive and negative circuit of three-terminal voltage-stabilizing integrated (7812 and 7912) are formed; Testing circuit 1 is by current transformer HI1, HI2, HI3, diode D14, D15, D16, capacitor C 6, potentiometer W1 forms, current transformer changes the electric current on the motor M and is converted on the potentiometer W1-variation of V1, amplifying circuit 2 is by operational amplifier A 1 (Im324), resistance R 9, R15-R18 forms, the negative input end of amplifier A1 inserts voltage (as 1.6V) by R16, be the benchmark protection value of this protector, and utilize the flat segments of magnetic saturation characteristic curve, voltage-V1 carries out positive and negative scale operation to potentiometer W1 swing arm: the ratio of electric motor protecting is 5 times, and, stablize with the swinging load motor and all can accurately adjust with instrument (voltmeter V) indication; The ratio of generating, power distribution protection is 10 times, selects for use by rated current, does not adjust, available light-emitting diode indication; Delay circuit 5 is made up of amplifier A3 (Im324), capacitor C 5, diode D6.Generating, distribution do not relate to the 6-7Ie starting current, and D6 can not add; Short-circuit protection circuit 6 is by amplifier A4, and resistance R 2, R3, R4, R8, R23 form.Wherein resistance R 23 (100K) guarantees the integrality of its protective feature curve 1.2-10Ie.Amplifier A4 positive input terminal inserts voltage by resistance R 4, and this voltage (as being 4V) is the short-circuit protection value of this protector; Trip circuit 7 is made up of controllable silicon SCR, relay K, diode D5, voltage stabilizing didoe DW, resistance R 1.Wherein controllable silicon aims at the automatic control motor use and establishes, relay control A.C. contactor break-make, and voltage stabilizing didoe prevents misoperation.

Operation principle of the present invention is: in motor when operation current transformer induced current is arranged, constitute path by potentiometer after the rectification of diode negative sense, it is corresponding with institute gas-distributing motor electric current to adjust potentiometer.When current of electric rises.Operational amplifier A 1 negative terminal voltage is for negative, A1 output end voltage V2 then, and V2=R17/R18V1 (potentiometer W1 swing arm voltage) finishes computing, and ((V7 is R20 and R21 node place voltage V7) time as V2 '＞V2+; V2 ' is the D8 cathode voltage), to capacitor C 5 charging ,-V4=1/R5C5 ∫ V2 ' dt (V4 is the A3 output end voltage) finishes integration by resistance R 5, V2 ' more the high charge time fast more, the inverse time protection characteristic curve that its can simulated dual sheet metal.When-when V1 reached to locked-rotor voltage, operational amplifier A 2 output end voltage V3 charged to capacitor C 5 by resistance R 12, diode D10, charging interval T=R12C5, and this moment, inverse time protection characteristic was finished separately by resistance R 23.When-when V1 reached short-circuit voltage, operational amplifier A 4 was overturn immediately and is exported V5 (A4 output end voltage), and the machine operation power supply is cut off in relay K adhesive and self-locking, and the controllable silicon outage promptly resets.If the normal starting electric current charges to C5, when starting current return zero moment C5 charging charge by diode D7, resistance R 6 to-V8 (R6 and R7 node place voltage) discharge, its charging interval begins to calculate again.If just having to rise, fault current do not fall, just can autostop in official hour, realized the reliability of protection action.Change voltage-V7 ,-V9 (R4 and R2 node place voltage), resistance R 12, can change the needs that the above big current protection of 2Ie adapts to generating, distribution, electric motor protecting practicality operate time.This protector is used for civil buildings can set up the overtension protection; as prevent that the neutral line 220V that gets loose from becoming 380V, and to set up earth leakage protective and prevent electric shock accidents etc., electric motor protecting must be set up phase-lacking protective unit; motor phase shortage accident accounts for the burn-down of electric motor total amount more than 70%, is one and lays special stress on protecting content.This protector model machine on April 15th, 1997 successive electricity move fault-free so far, to the motor phase shortage, overload, stall, voltage 320V, the conversion of Y-Δ is malfunctioning all can reach effective protection.

The relation of electric current multiple of the present invention and-V1: Ie=1.4V; 1.2Ie=1.78V; 1.5Ie=2.15V; 2Ie=3.05V; 3Ie=4.4V; 4Ie=4.7V; 5Ie=5.7V; 6Ie=6.6V.

Fig. 3 illustrate according to experiment measure electric current of the present invention with and protective effect time continually varying function relation curve, its protection operating characteristics index is: 1.05Ie is failure to actuate; 1.2Ie≤6min; 1.5Ie≤3min; 6Ie≤5S; 10Ie wink moving (the special-purpose 6Ie≤8S of blower fan all the other constant).

The present invention compared with prior art has following advantage: 1, have protection feature curve complete sum continuity; 2, to electricity Device, the especially protection of motor dynamics parameter have high stability, i.e. uniformity and the repeatability of protection action index; 3, Realized all-round protection and the all-round purpose of using, can carry out overload, phase shortage, seize, stall, the short circuit of motor All-round protection.

Claims

1, a kind of electrical equipment overcurrent electronic protector, comprise voltage-stabilized power supply circuit, the dynamic testing circuit of alternating current (1), 1.2Ie ratio amplifying circuit (2), inverse time-lag circuit (5), short-circuit protection circuit (6), trip circuit (7), the dynamic testing circuit of above-mentioned alternating current (1), 1.2Ie ratio amplifying circuit (2), inverse time-lag circuit (5), short-circuit protection circuit (6), trip circuit (7) cascade in turn; The dynamic testing circuit of above-mentioned alternating current (1), short-circuit protection circuit (6), trip circuit (7) cascade in turn is characterized in that, also comprise:

A), big electric current accelerating circuit operate time (3): form by operational amplifier (A2), the 19 resistance (R19), the 20 resistance (R20), the 21 resistance (R21), the 22 resistance (R22); The negative input end of operational amplifier (A2) is connected behind the 19 resistance (R19), be connected to the output of the dynamic testing circuit of described alternating current (1), the positive input terminal of operational amplifier (A2) is connected and is connected to an end of the 21 resistance (R21), the 22 resistance (R22) behind the 20 resistance (R20) respectively, the described voltage-stabilized power supply circuit cathode output end of another termination of the 21 resistance (R21), the 22 resistance (R22) other end ground connection;

B), protection action index stabilizing circuit (4): form by the 7th diode (D7), the 8th diode (D8), the tenth diode (D10), the 5th resistance (R5), the 6th resistance (R6), the 7th resistance (R7), the tenth resistance (R10), the 12 resistance (R12), the 13 resistance (R13); Behind the tenth diode (D10) anodal series connection the 12 resistance (R12), the output that is connected to above-mentioned big electric current accelerating circuit operate time (3) is the output of operational amplifier (A2), the tenth diode (D10) negative pole and the 7th diode (D7) positive pole all are connected to the input of described inverse time-lag circuit (5), the 7th diode (D7) negative pole the 6th resistance in sequential series (R6), the 7th resistance (R7) back ground connection, the 13 resistance (R13) one is terminated at the interface point of the 6th resistance (R6) and the 7th resistance (R7), the cathode output end of the described voltage-stabilized power supply circuit of another termination of the 13 resistance (R13), the 8th diode (D8) negative pole is connected to the 7th diode (D7) negative pole, behind the 8th diode (D8) anodal series connection the tenth resistance (R10), be connected to the output of 1.2Ie ratio amplifying circuit (2).

2, protector according to claim 1 is characterized in that, also has the 12 light-emitting diode (D12), the 13 light-emitting diode (D13), the 14 resistance (R14) in described big electric current accelerating circuit operate time (3); Anodal and the 13 light-emitting diode (D13) minus earth of the 12 light-emitting diode (D12), the 12 light-emitting diode (D12) negative pole and the 13 light-emitting diode (D13) positive pole are all connected behind the 14 resistance (R14), are connected to the output of operational amplifier (A2).