CN1026194C

CN1026194C - Multifunctional Insulation Monitor

Info

Publication number: CN1026194C
Application number: CN 92107518
Authority: CN
Inventors: 袁振海
Original assignee: NANJING CONSTRUCTION ENGINEERING COLLEGE
Current assignee: NANJING CONSTRUCTION ENGINEERING COLLEGE
Priority date: 1992-04-18
Filing date: 1992-04-18
Publication date: 1994-10-12
Anticipated expiration: 2007-04-18
Also published as: CN1064948A

Abstract

The multifunctional insulation monitor is used for monitoring the insulation state of a low-voltage neutral point ungrounded power supply system and comprises a detection device, a comparator, an alarm device and a power supply. An active filter is arranged between the detection device and the comparator, the alarm device consists of a logic circuit, an acoustic alarm and an optical alarm, the reference signal end of the comparator is connected with an adjustable reference circuit, the power supply consists of three groups, and monitors required by different occasions can be combined by connectors with different functions. The device has the advantages of simple structure, small volume, power consumption saving, safe and reliable use and the like, and is suitable for monitoring the insulation performance of an alternating current load system and a direct current load system.

Description

Multifunction insulating monitor

The present invention is the insulating monitor that a kind of usefulness is given low pressure isolated neutral electric power system, belongs to electric power system insulating property surveillance technology field.

Existing low-voltage power supply system generally adopts earth neutral system, and this system is in case a phase ground connection, and short-circuit current is big, accident such as cause that easily fire, explosion disaster and the person are died because of being killed by an electric shock.Can adopt the isolated neutral electric power system to the demanding unit of power supply safety (for example hospital, chemical plant, cotton mill etc.), the ground current of this system is very little, but, because the ground current of isolated neutral electric power system is small, often be not easy to discover, after the phase ground connection, several days so the longer time can not in time find and handle, cause other two phase voltages to raise, cause and produce main dangerous possibility.

The objective of the invention is at the deficiencies in the prior art, a kind of insulating monitor that is used for low pressure isolated neutral electric power system is provided, just give advance notice when making its insulating property also not drop to complete damaged condition (promptly also not forming dead ground), prevent trouble before it happens.

The present invention is made up of pick-up unit, reference circuit, comparer, warning device and power supply, it is characterized in that being provided with active filter (2) between pick-up unit (1) and the comparer (4), power supply (6) is connected with the detection alarm card i/f with pick-up unit (1), reference circuit (3) and comparer (4), active filter (2) respectively, warning device is made of logical circuit, light warning harmony alarm, pick-up unit (1) is made of resistance, induction reactance coil, electric capacity, reometer, sampling potentiometer, direct supply and switch, switch K ₁～K ₅Place various on off states, the insulation that connects corresponding circuit card, formation all kinds electric power system detects monitor.For the ease of requiring to regulate insulation numerical value and alarm threshold according to varying environment, reference circuit adopts adjustable reference circuit.For ease of special circumstances such as processing electric shocks in time, instrument can be provided with high speed detector.For can periodic inspection instrument operate as normal whether, experimental provision can be set in instrument, thereby can under the situation of the normal operation of circuit, instrument be tested.

Decapacitation of the present invention monitors beyond the insulation status of AC load, can also the rectifying installation of installing on the power circuit be monitored.When the negative or positive electrode ground connection of rectifying installation, the present invention can selectively show and reports to the police it.When fairing power was big, instrument was provided with the autoprotection device, in order to avoid the damage that may bring to instrument during rectification ground connection.On power circuit, have only rectifier power source with rectification load the time, the present invention can be used as selectable alternating current-direct current ground connection and shows and warning device, alternating current-direct current earthing alarm unit of the present invention, warning device and the DC load insulation detection alarm device controlled by main circuit, logical circuit constitute.

The present invention compared with prior art, have simple in structure, volume is little, little power consumption, advantage such as safe in utilization and reliable.This instrument can be informed the insulating property situation of electric power system at any time, and can in time remind electrical technology personnel inspection accident potential.When even a phase ground connection is arranged, supply line can uninterrupted power supply, the operator on duty is interruption maintenance at the convenient time, this is very important to the usefulness electric unit that hospital operating room etc. can not have a power failure at any time, to giving the enterprises and institutions that those must use fairing, this instrument provides the detection means that adopts isolated neutral system, when ground connection is surveyed in rectification, not only can sound and light alarm, and can show it is which side joint ground of direct supply respectively by two light emitting diodes.Simultaneously, can also insert by on-delay and power-off delay relay group automatic protection resistance and detect the loop, in order to limit the influence of the interference DC voltage that in detecting the loop, forms because of DC earthing.When zero line or live wire ground connection, alerting signal takes place in warning device immediately, makes the red lamp flass of instrument, electric bell send chimes of doom.If maintenance is immediately given in operator on duty's inconvenience, can also press and stop button, make electric bell stop sound, and make the red light of flicker become Chang Liang, show accident releasing as yet.Have only after accident is got rid of, red light just extinguishes, and instrument returns to normal operating conditions.

Fig. 1 is a structure block diagram of the present invention; Fig. 2 is a main circuit schematic diagram of the present invention; Fig. 3 is the warning device circuit theory diagrams of logical circuit control; Fig. 4 is the warning device circuit theory diagrams of relay control; Fig. 5 is the high speed detector circuit theory diagrams; Fig. 6 is the insulation detection alarm device circuit figure of DC load; Fig. 7 is the DC load insulation detection alarm device circuit figure with protection of instrumentation function; Fig. 8 is the DC load insulation detection alarm device circuit figure with adjustable protection of instrumentation function.

The present invention can adopt scheme shown in the drawings to realize.Pick-up unit (1) can be by K ₁～K ₅, resistance R ₁₁, R ₂₁, R ₃₁Induction reactance coil L ₁, direct supply E ₃, capacitor C ₁₁, reometer (K Ω) and sampling potentiometer W ₁₁And W ₂₁Constitute L with big induction reactance ₁Be connected between artificial neutral point of circuit and the ground wire, the size of current by reometer depends on the insulation resistance that gives line-to-ground in size, and in order directly to read the size of insulation resistance, reometer is represented by the numerical scale of resistance, is K Ω table.Direct supply E ₃Be serially connected in and measure in the loop, through reactance coil L ₁→ resistance R ₁₁, R ₂₁, R ₃₁→ electrical network → electrical network insulation against ground resistance → W ₂₁, W ₁₁→ K Ω table constitutes DC loop, when the electrical network insulation against ground changes, measures current in loop and changes thereupon, at W ₂₁Last generation voltage measurement signal.Pick-up unit (1) passes through K switch ₁, K ₂, K ₃And K ₄Be pressed into the line power transformer B that is monitored ₁Secondary.Power supply (6) is made of transformer B, rectification circuit, filtering circuit and three-terminal voltage-stabilizing integrated package 7812,7912,7824,7924, and power supply can be divided into three groups, wherein E ₁Provide-12 volts and+12 volts of voltages, E ₂Provide-24 volts, E ₃Provide+24 volts of voltages.Active filter (2) can be made of emitter follower, second-order active filter device, subtracter, high-order harmonic filtering device, circuit as shown in Figure 2, ic chip ₁₁, IC ₂₁, IC ₃₁, IC ₄₁Can adopt LM324,2 * 5G353 or μ A747 circuit.The adjustable reference circuit that reference circuit (3) can adopt mu balanced circuit and emitter follower to constitute is by ic chip ₆₁, IC ₇₁, voltage stabilizing diode D ₁₁, resistance R ₁₅₁, potentiometer W ₃₁, W ₄₁And W ₅₁Constitute W ₃₁, W ₄₁And W ₅₁Be attempted by D after the series connection ₁₁Two ends, W ₄₁Moving contact meet IC ₇₁In-phase input end, IC ₇₁Output terminal connecting resistance R ₁₇₁, IC ₆₁, IC ₇₁Available LM324 circuit.Comparer (4) can adopt hysteresis voltage comparer IC ₈₁(5G353) form: IC ₅₁Form follower, available LM324 circuit; The signal of comparer output is through amplifier pilot relay J ₁, the transistor T of amplifier ₁₁Can adopt 3DG6 or 3DK ₂, relay J ₁Can adopt JRC-5M, J ₁Signal be input to warning device.

For whether the work of checking insulation detection device is normal, the present invention is provided with experimental provision, and it can be by button SB ₁And resistance R ₄₁Polyphone constitutes, and when the supply line place gives normal operating conditions, presses the button SB ₁, instrument can send alerting signal, release button SB ₁, instrument recovers normal operating conditions again.FU among Fig. 2 is a fuse, K ₁, K ₂, K ₃, K ₄And K ₅Be switch, HLO is (power supply) pilot lamp, D ₂₁Be two oppositely stabilivolts of serial connection, D ₃₁Be diode, R ₁₁, R ₂₁R ₂₃₁Be resistance, C ₁₁, C ₂₁C ₆₁Be electric capacity, bracket 1., 2. ... (13) be connected with the corresponding label of other accompanying drawing.Detection alarm card i/f (5) can be used to be connected with various detection alarm plug-in units, warning device shown in Figure 3 can be made up of logical circuit, light crossing-signal harmony alarm, circuit also can be made up of relay, light crossing-signal harmony alarm as shown in Figure 3, and circuit as shown in Figure 4."～" expression among Fig. 3 and Fig. 4 external or 380 volts or 220 volts of AC power being connected with instrument internal.Resistance R among Fig. 3 ₁₂₂, R ₁₃₂, R ₁₄₂, R ₁₅, R ₁₅₂, capacitor C ₆₂, C ₇₂With diode D ₅₂, D ₆₂Form and send into signal gate, relay J ₁The signal of output is input to logical circuit through sending into signal gate, and logical circuit is by IC ₁₂, IC ₂₂, IC ₃₂, IC ₄₂, IC ₅₂And IC ₆₂Constitute, they can adopt the 5G601 integrated package to form.Logic circuit output signal one tunnel is through transistor T ₂₂Amplify whether conducting of back control bidirectional triode thyristor BCR, realize red eye HL _RDWhether report to the police.Another road signal controlling phase inverter (phase inverter is in 5G605) output high level of logical circuit output promotes T ₁₂Conducting makes J ₂Adhesive is connected electric bell and is sent acoustic alarm.T ₁₂Can adopt 3DG _130B, J ₂Can adopt JQX-4F, T ₂₂Adopt 3CG _14CRing oscillator is mainly by 5G ₆₀₅Phase inverter in the integrated package is equipped with resistance, electric capacity constitutes, and produces about 1～2 second oscillator signal of frequency.When the insulating property that are equipped with when electric letter are reduced to the minimum insulating resistance value of permission, measure in the loop current value is correspondingly just arranged, this can indicate by reometer on the one hand, form a voltage signal on the other hand on sampling potentiometer, it and AC signal are superimposed, and take out its direct current signal through active filter, be input to comparer and reference signal relatively, make the circuit state upset, the output high level promotes transistor T ₁₁Conducting makes J ₁Adhesive is sent into an one state to logical circuit.At this moment, logical circuit is under the oscillator signal control that ring oscillator produced, and output signal constantly changes, and is disconnected when opening when making bidirectional triode thyristor, red eye HL _RDFlash.The while transistor T ₁₂Conducting makes relay J ₂Adhesive, electric bell HA sends acoustic alarm.D among Fig. 3 ₁₂, D ₃₂, D ₄₂, D ₅₂, D ₆₂Be diode, D ₂₂Be stabilivolt, R ₁₂, R ₂₂R ₁₁₂Be resistance, C ₁₂, C ₂₂C ₅₂Be electric capacity, SB ₁₂Be ACK button, press SB ₁₂Output signal that can control logic circuit is so as to turn-offing acoustic alarm.Simultaneously, the flashing signal that light is reported to the police becomes Chang Liang, and after accident was removed, instrument became normality.SB ₂₂Be moving examination button, can be used for testing warning circuit operate as normal.

For make warning device can be relatively poor in environmental baseline the place of (harmfulness gas or there was dampness in the air) use be convenient to maintenance, can adopt circuit shown in Figure 4.It is by relay J ₃And J ₄, diode D ₁₃And D ₂₃, signal lamp HL _RD, electric bell HA and button SB ₁₃Constitute J ₃Can adopt JTX-3, J ₄Can adopt JTX-1, HA can adopt UC ₄-75/380V.

In order to make instrument in time and promptly reflect the line insulation performance condition, the present invention can be provided with high speed detector.Circuit as shown in Figure 5, it by the analog to digital converter coding circuit and decoding display circuit form integrated circuit (IC) among the figure _1-7Form voltage comparator, can adopt J ₁₃₉Or the LM324 circuit is realized; IC _8～13Form coding circuit, can adopt 5G604,5G607 circuit to realize; Decoding scheme can be made of signal lamp HL 4 5G603 circuit _1～8Demonstrate the different situations of line insulation performance.D among the figure _1～7Be the oppositely stabilivolts of serial connection of 7 pairs of two stabilivolts, R ₁₄, R ₂₄R ₂₃₄Be resistance, Q ₁, Q ₂, Q ₄The expression output terminal.

In order to make the present invention can be applicable to existing AC load, have wireline inspection by the DC load of commutated current power supply again, the present invention can set up DC load insulation detection alarm device, circuit such as Fig. 6.It is by two comparer LM393, transistor T ₁₅And T ₂₅, diode D ₁₅And D ₂₅And D ₃₅, light emitting diode D ₄₅And D ₅₅, relay J ₅And J ₆, resistance R ₁₅, R ₂₅, R ₃₅, R ₄₅Form, wherein T ₁₅And T ₂₅Can adopt 3DG6, J ₅And J ₆Can adopt JRC-5M, two comparers adopt the out-phase structures, the anti-phase termination of last comparer 9., following comparer homophase termination 8., 7. another input end of two comparers all connects, the power pin of two comparers is D directly ₃₅Connect 3., the output terminal of two comparers is respectively through R ₂₅, R ₄₅Meet T ₁₅, T ₂₅Base stage, emitter respectively with J ₅, J ₆Normally opened contact one end connect J ₅Another termination of normally opened contact D ₄₅; J ₆A normally opened contact meet D ₅₅, 10. another normally opened contact connects.Reference signal value difference is delivered to in-phase end for one, and another sends into end of oppisite phase, though comparison signal is same signal, and an input in-phase end, another input inversion end.

Under rectifier power source voltage condition with higher; during one utmost point ground connection; generally can in measuring the loop, form one and disturb DC voltage; for the adverse effect that prevents that it from may bring instrument; can set up the DC load insulation detection alarm device with protection of instrumentation function, circuit as shown in Figure 7.It has increased measurement loop current-limiting apparatus on circuit base shown in Figure 6, and adopts the hysteresis voltage comparer.It constitutes by measuring loop current-limiting apparatus and DC load insulation detection alarm device, measuring the loop current-limiting apparatus is made of on-delay and power-off delay relay and current-limiting resistance, joint 1., 2., 3., 4., 5., 7., 8., 9., 10., (13) all connect power-off delay relay KT with the respective point of main circuit ₂₆Time-delay contact and current-limiting resistance R ₁₃₆After the series connection, again with energization delay relay KT ₁₆The two ends parallel connection of time-delay contact, on it termination 1., following termination 2., KT ₁₆And KT ₂₆Coils from parallel connection of coils, its upper end and relay J ₇And J ₈Normally opened contact connect following termination (13).Ic chip ₁₆, IC ₂₆Can adopt the 5G353 circuit, transistor T ₁₆, T ₂₆Can adopt 3DG ₆, relay J ₇, J ₈Can adopt JRC-5M, KT ₁₆, KT ₂₆Can adopt JS ₇-A, D ₁₆, D ₂₆Be stabilivolt, D ₃₆, D ₄₆Be diode, D ₅₆, D ₆₆Be light emitting diode, R ₁₆, R ₂₆R ₁₃₆Be resistance, C ₁₆And C ₂₆Be electric capacity.

In order to make instrument can be applicable to the occasion of different rectifier power source voltages, the present invention is provided with the DC load detection alarm display with adjustable protection of instrumentation function, and its circuit as shown in Figure 8.It increases by a group relay on circuit base shown in Figure 7, it is made of adjustable measurement loop current-limiting apparatus and DC load insulation detection alarm device, and adjustable measurement loop current-limiting apparatus is by timing relay KT ₁, KT ₂, KT ₃, KT ₄Constitute with regulator potentiometer.KT ₁And KT ₂Coils from parallel connection of coils after upper end and relay J ₉Normally opened contact connect.KT ₃And KT ₄Coils from parallel connection of coils after upper end and relay J ₁₀Normally opened contact connect.Its lower end all connects (13); KT ₁, KT ₂, KT ₃, KT ₄The upper end of delayed contact meet 1. KT after connecting ₁, KT ₃The time-delay contact the lower end respectively with KT ₃And KT ₁Snap action contact connect, KT ₂And KT ₄The lower end be connected with potentiometer, all connect 2. then.Ic chip ₁₇And IC ₂₇Can adopt the 5G353 circuit, transistor T ₁₇, T ₂₇Can adopt 3DG6, relay J ₉, J ₁₀Can adopt JRC-5M, timing relay KT ₁, KT ₂, KT ₃And KT ₄Can adopt JS ₇-A, D ₁₇And D ₂₇Be diode, D ₃₇And D ₄₇Be stabilivolt, D ₅₇And D ₆₇Be light emitting diode, R ₁₇, R ₂₇R ₁₂₇Be resistance.C ₁₇And C ₂₇Be electric capacity.

In order to make instrument can adapt to the different request for utilizations of different occasions, the present invention takes inserter structure, and main circuit shown in Figure 2 is fixed on the frame, and Fig. 3～each piece circuit shown in Figure 8 is plug-in type, can makes up as required like this.

When (one), measuring transformer secondary line voltage is 380 volts:

K switch ₁→ 1, K ₂→ 3, K ₅→ 1

(1), load is under the situation of AC load basically, K ₃→ 2, K ₄→ 4, this moment is as long as by main circuit and circuit card 1 combination shown in Figure 3, just can carry out insulating property and detect.Measure fast if desired, then as long as with K ₄→ 3, insert high speed detector circuit card 3 as shown in Figure 5 again, just can carry out fast detecting.High speed detector makes the capacitor C in the main circuit ₁₁Disconnect with K Ω table, the display part is made up of three parts: the one, and analog to digital conversion, its handle converts the corresponding digital amount to the analog quantity of the insulation resistance relation of being inversely proportional to; The 2nd, digital quantity is sent into coding circuit; The 3rd, the coding circuit output signal is delivered to the on-off that decoding scheme promotes display lamp, so as to the scope at expression insulation resistance place.

(2) the existing AC load of load, when having the DC load of powering again by rectifier power source:

If rectifier power source power is less, then make K ₃→ 2, K ₄～3, on the basis of main circuit, plug-in unit 1 and plug-in unit 3, insert circuit card shown in Figure 64 again, plug-in unit 4 is made of two out-phase comparers.When two of direct supplys were extremely earth-free, direct supply was working properly, and high speed detector demonstrates the state of insulation of AC load.When insulating resistance value was lower than the numerical value of prior setting, instrument sent alerting signal.When two utmost points of direct supply respectively during ground connection, a utmost point ground connection can make main circuit measure loop current to be increased, and another utmost point ground connection can make main circuit measure loop current to reduce, even oppositely.In both cases, main circuit is measured in the loop and has been added interference, but it is clocklike, and one of comparison signal is much larger than normal condition.Another is much smaller than normal condition.When the signal of comparison signal under normal condition,, promote triode T with phase comparator output high level ₁₅Conducting makes relay J ₅Adhesive, its normally opened contact closure; Because light emitting diode D ₄₅A current-limiting resistance R connects ₁₅Be connected to positive supply and J ₅Between one end of normally opened contact, and J ₅The other end of normally opened contact links to each other with reference point, so light emitting diode D ₄₅Luminous, meanwhile, the comparison signal of main circuit hysteresis voltage comparer makes its upset, promotes the relay adhesive, sends alerting signal, shows that direct current one side has an accident, and just returns to normal after accident is removed.When comparison signal during much smaller than the signal of normal condition, this signal is added to the end of oppisite phase of anti-phase comparer, and when this signal was lower than the reference signal of in-phase end, comparer output high level made transistor T ₂₅Conducting, relay J ₆Adhesive makes light emitting diode D ₅₅Luminous, shown another utmost point ground connection of direct supply.Light emitting diode is not luminous if alerting signal is arranged, and shows it is that AC side has problem, and at this moment the display lamp of high speed detector is bright, thereby judges the insulating property situation.

If rectifier power source voltage is very high, at this moment K ₃→ 1, K ₄→ 3, plug-in unit 4 need be changed into circuit card 5 as shown in Figure 7.In this case, direct current one side joint ground gives the measurement interference current that cause in the loop big, may damage detecting instrument.Damage for fear of detecting instrument, be provided with in the plug-in unit 5 and measure the loop current restraint device.This device is mainly by energization delay relay KT ₁₆With power-off delay relay KT ₂₆Constitute.When making the direct supply side joint ground of main circuit current increase, last hysteresis comparator upset, light emitting diode D ₅₆Luminous, J ₇KT is connected in adhesive simultaneously ₁₆And KT ₂₆, KT ₂₆Electric after, its dead electricity time-delay breaking-off contact moment closure is KT ₁₆The time-delay contact gets the time-delay disconnection of electric back and has prepared condition, has avoided KT ₁₆The time-delay contact disconnects, may occur when sealing in resistance measuring the loop of short duration open circuit may with the problem of bringing.After one adjustable period, KT ₁₆The time-delay contact disconnects, and so just can make to measure the loop and do not open circuit and seal in current-limiting resistance safely.Meanwhile, alerting signal is sent in the upset of main circuit comparer, shows the accident source, after accident is removed, and J ₇Discharge KT ₁₆, KT ₂₆While dead electricity, but KT ₁₆Time-delay contact dead electricity the time instantaneous closure, and KT ₂₆A period of time of then delaying time during time-delay contact dead electricity just disconnects, and avoids measuring the loop and of short duration breaking phenomena may occur.When the direct supply other end (utmost point) ground connection, following hysteresis comparator action seals in current-limiting resistance also for the measurement loop, gives the alarm simultaneously and shows signal.Be that with above-mentioned situation difference at this moment the main circuit comparer is failure to actuate, alerting signal is by J ₈Provide.Here the purpose that adopts hysteresis comparator is reliably to overturn when guaranteeing comparison signal near reference value.When the direct current source earth fault do not occur, the insulation status of AC load was shown by high speed detector, is reported to the police by the control of main circuit comparer.

When rectifier power source voltage is higher, for adjust easily two utmost points of direct supply respectively during ground connection should seal in the size of measuring current-limiting resistance value in the loop, at this moment only need plug-in unit 5 is taken off, change circuit card shown in Figure 86 and get final product.Plug-in unit 6 is with the difference of plug-in unit 5: the last hysteresis comparator of plug-in unit 6 and the following J that hysteresis comparator promoted ₉And J ₁₀Controlling one group of on-delay and power-off delay relay respectively.KT ₁KT during normally closed contact (non-time-delay) must be organized with another ₃Time-delay break contact (on-delay) string together.In like manner, KT ₃Non-delayed contact and KT ₁Normally closed time-delay break contact is serially connected.

When (3) load has only DC load, also can divide three kinds of situations:

When rectifier power source power hour, K ₃→ 2, K ₄→ 3, need only main circuit and plug-in unit 1, plug-in unit 4 combinations.At this moment the corresponding raising of the reference voltage of main circuit comparer (realizing by rotating potentiometer) should be brought up to the comparison signal that is produced when AC side has ground connection and compared with it, the upset of main circuit hysteresis comparator.In this case, instrument is carried out AC and DC grounding alarm Presentation Function.

When rectifier power source voltage is very high, K ₃→ 1, K ₄→ 3, as long as main circuit, plug-in unit 1 and plug-in unit 5 combinations.The reference voltage of at this moment corresponding raising main circuit comparer makes it ground connection be arranged or can overturn during by " experiment " button in AC side and get final product.

When rectifier power source voltage is higher, K ₃→ 1, K ₄→ 3, as long as main circuit, plug-in unit 1 and plug-in unit 6 combinations.Should note the reference voltage of corresponding raising main circuit comparer equally.

(2), when measuring transformer secondary line voltage is 220 volts, K ₁→ 1, K ₂→ 4, K ₅→ 2.Because a part of coil of measuring the loop reactor should corresponding change W by short circuit ₁₁Seal in the resistance of measuring in the loop, so as to guaranteeing the AC and DC internal resistance of instrument.This situation still can be divided into following various situation:

(1), load mainly is the situation of AC load; (2), the existing interchange of load has the situation of DC load again; (3), load has only the situation of DC load.The plug-in unit combination of various situations is with the function that is realized and measure 380 volts (one) roughly the same, and single-phase 220 volts situation is also like this.

(3), when measuring 220 volts of single transformer secondary, K ₁→ 2, K ₂→ 4, K ₅→ 2.At this moment, connection electrical resistance R ₂₁, R ₃₁Should join with single-phase source transformer secondary through switch.Because have only two connection resistance and circuit to link, a reactance coil part of measuring the loop should be regulated W by short circuit ₁₁Resistance so that the desirable AC and DC internal resistance that obtains.This situation still can be divided into load and be essentially AC load, and the existing interchange of load has DC load again, and load has only situations such as DC load.

Have only DC load for load, rectifier power source power is less, and ground current is very little, service area is little, instrument is not far apart from the work place, be not under the too high situation to safety requirements, can consider not acoustic alarm.The measuring circuit of above situation can be without plug-in unit 1.Simultaneously, the reference voltage of hysteresis voltage comparer in the main circuit is improved, the reference voltage of the last comparer of plug-in unit 4 is suitably reduced, it can be overturn when interchange one phase ground connection.As light emitting diode D ₄₅When bright, two possibilities are arranged: the one, a utmost point ground connection of direct current; The 2nd, exchange ground connection, and at light emitting diode D ₅₅When bright, only show another utmost point ground connection of direct current.As long as utilize J ₁A normally opened contact, at J ₁One end of normally opened contact connects a light emitting diode and by the resistance current limliting to increasing between the positive supply, just can at an easy rate above-described two may be separated, just interchange, DC earthing are shown separately, at this moment, answer the reference signal of corresponding change main circuit comparer.So just can judge the various situations of AC and DC power ground according to the luminous situation of light emitting diode.

Claims

1, a kind of multifunction insulating monitor that is used for low pressure isolated neutral electric power system, by pick-up unit, reference circuit, comparer, warning device and power supply are formed, it is characterized in that being provided with active filter (2) between pick-up unit (1) and the comparer (4), power supply (6) respectively with pick-up unit (1), reference circuit (3) and comparer (4), active filter (2) is connected with the detection alarm card i/f, warning device is by logical circuit, light warning harmony alarm constitutes, pick-up unit (1) is by resistance, the induction reactance coil, electric capacity, reometer, sampling potentiometer, direct supply and switch constitute, switch K ₁～K ₅Place various on off states, connect corresponding circuit card, the insulation that constitutes all kinds electric power system detects monitor:

(1), K ₁→ 1, K ₂→ 3, K ₅→ 1 o'clock, R ₁₁, R ₂₁, R ₃₁Constitute artificial neutral point through high resistance grounding, the insulation that constitutes 380 volts of this phase electric power systems detects monitor; With K ₁→ 1, K ₂→ 4, K ₅→ 2, the insulation that then constitutes 220 volts of three-phase power supply systems detects monitor; Cooperate and change K ₃, K ₄On off state 1 connect corresponding circuit card, can constitute the insulation detection alarm device of heterogeneity load:

(1) K ₃→ 2, K ₄→ 4, main circuit is connected with the warning device of logical circuit control, constitutes AC load insulation detection alarm device;

(2) K ₃→ 2, K ₄→ 3, the warning device of main circuit and logical circuit control, high speed detector, DC load insulation detection alarm device constitute the insulation detection alarm device that existing AC load has the DC load of being powered by rectifier power source again;

(3) K ₃→ 1 or 2, K ₄→ 3, the warning device of main circuit and logical circuit control, DC load insulation detection alarm device or the DC load insulation detection alarm device that has the DC load insulation detection alarm device of protection of instrumentation function or have an adjustable protection of instrumentation function are connected, constitute the DC load detection alarm device that insulate;

(2), K ₁→ 2, K ₂→ 4, K ₅→ 2 o'clock, R ₂₁, R ₃₁The upper end gets access to grid respectively, and the lower end is unified into any through high resistance grounding, and the insulation that constitutes 220 volts of single phase power supply systems detects monitor, changes K ₃, K ₄On off state, and connect corresponding circuit card, can constitute the insulation detection alarm device of heterogeneity load.

2, multifunction insulating monitor according to claim 1 is characterized in that comparator input terminal is connected to adjustable reference circuit, and it is made of mu balanced circuit and emitter follower, potentiometer W ₃₁, W ₄₁And W ₅₁Be attempted by stabilivolt D after the series connection ₁₁Two ends, W ₄₁Moving contact be connected to IC ₇₁In-phase input end, IC ₇₁Output terminal is through resistance R ₁₇₁Be connected to the IC of comparer ₈₁Inverting input.

3, multifunction insulating monitor according to claim 1 is characterized in that being provided with experimental provision, and it is by button SB ₁And resistance R ₄₁Constitute.

4, according to claim 1,2 or 3 described multifunction insulating monitors, it is characterized in that being provided with high speed detector, it is made of analog to digital converter, coding circuit and decoding display circuit.

5, according to claim 1,2 or 3 described multifunction insulating monitors, it is characterized in that being provided with DC load insulation detection alarm device, it is by comparer (LM393), the resistance R of two out-phase inputs ₁₅, R ₂₅, R ₃₅, R ₄₅, transistor T ₁₅, T ₂₅, diode D ₁₅, D ₂₅, D ₃₅, light emitting diode D ₄₅, D ₅₅And relay J ₅, J ₆Constitute, the anti-phase termination of last comparer 9., following comparer homophase termination 8., 7. another input end of two comparers all connects, the power pin of two comparers is through D ₃₅Connect 3., the output terminal of two comparers is respectively through R ₂₅, R ₄₅Meet T ₁₅, T ₂₅Base stage, emitter respectively with J ₅And J ₆Normally opened contact one end connect J ₅Another termination of normally opened contact D ₄₅; J ₆A normally opened contact meet D ₅₅, 10. another normally opened contact connects, and joint is 3., 7., 8., 9., 10. all connect with the respective point of main circuit.

6, multifunction insulating monitor according to claim 5; it is characterized in that being provided with DC load insulation detection alarm device with protection of instrumentation function; it constitutes by measuring loop current-limiting apparatus and DC load insulation detection alarm device; measuring the loop current-limiting apparatus is made of on-delay and power-off delay relay and current-limiting resistance; joint 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., (13) all connect power-off delay relay KT with the respective point of main circuit ₂₆Time-delay contact and current-limiting resistance R ₁₃₆After the series connection, again with energization delay relay KT ₁₆The two ends parallel connection of time-delay contact, on it termination 1., following termination 2., KT ₁₆And KT ₂₆Coils from parallel connection of coils, its upper end and relay J ₇And J ₈Normally opened contact connect following termination (13).

7, multifunction insulating monitor according to claim 6; it is characterized in that being provided with DC load insulation detection alarm device with adjustable protection of instrumentation function; it is made of adjustable measurement loop current-limiting apparatus and DC load insulation detection alarm device, and adjustable measurement loop current-limiting apparatus is by timing relay KT ₁, KT ₂, KT ₃, KT ₄Constitute KT with regulator potentiometer ₁And KT ₂Coils from parallel connection of coils after upper end and relay J ₉Normally opened contact connect KT ₃And KT ₄Coils from parallel connection of coils after upper end and relay J ₁₀Normally opened contact connect, its lower end all connects (13); KT ₁, KT ₂, KT ₃, KT ₄The upper end of delayed contact meet 1. KT after connecting together ₁And KT ₃The time-delay contact the lower end respectively with KT ₃And KT ₁Snap action contact connect KT ₂And KT ₄The lower end be connected with potentiometer, all connect 2. then, joint 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., (13) all be connected with the respective point of main circuit.

8, according to claim 1,2 or 3 described multifunction insulating monitors, it is characterized in that being provided with the AC and DC earthing alarm unit, it is made of the warning device and the DC load insulation detection alarm device of main circuit, logical circuit control.