CN103983857B - A kind of D.C. isolation observation circuit and method - Google Patents
A kind of D.C. isolation observation circuit and method Download PDFInfo
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Abstract
The invention discloses a kind of D.C. isolation observation circuit and method, wherein observation circuit includes：Resistance switch unit, it includes three ends, wherein first end is connected with the positive pole of monitored straight-flow system, the second end is connected with the negative pole of monitored straight-flow system, and resistance switch unit can mutually switch the resistance between the resistance between first end and the 3rd end and the second end and the 3rd end；First resistor, its one end is connected with the 3rd end of resistance switch unit, and the other end is connected to ground；First voltage measuring unit, it is connected to the positive and negative end of monitored straight-flow system；Second voltage measuring unit, it is connected to first resistor two ends.Using Low-voltage Electronic switching device and single bridge circuit in the observation circuit that the present invention is provided, advantageously reduce circuit cost and extend the service life of circuit, so as to improve the dependable with function of circuit.
Description
Technical field
The present invention relates to electric and electronic technical field, specifically, it is related to a kind of D.C. isolation observation circuit and method.
Background technology
The running status of the power equipment DC side such as current transformer directly influences the safety and reliability of power system.This
Insulation fault once occurs for the DC side of a little power equipments, will cause protective relaying device misoperation, causes power supply trouble even
The damage of high power device.In order to prevent such accident from occurring, it is necessary to use insulating monitoring circuit.
Insulating monitoring is mainly detection Grounding Resistance for Direct-Current System, and whether straight-flow system is judged by the resistance detected
Generation DC ground fault.The method of existing detection Grounding Resistance for Direct-Current System mainly has balanced bridge method and double uneven electricity
Bridge method.
Fig. 1 shows the circuit theory diagrams of balanced bridge method.
As shown in figure 1, balanced bridge method is the equivalent grounding resistance R of both positive and negative polarity with straight-flow systemz、RfWith two resistance phases
The electric bridge of same resistance R101, R102 composition is detected.
When system is normal, i.e. when the insulation status of system is good, because now positive pole and negative pole insulation against ground resistance RzAnd Rz
Resistance it is equal, flowed through so only having small out-of-balance current in relay 103, and less than the operating current of relay 103,
So now relay does not work, alarm free signal is produced.
When working as the negative or positive electrode ground connection of system jam, i.e. system, the electricity being made up of resistance R101 and resistance R102
Bridge disequilibrium, is now flowed through in relay 103 by larger out-of-balance current.When the electric current is more than the work of relay 103
During electric current, relay 103 works, and produces alarm signal.
But for the equivalent grounding resistance R of both positive and negative polarityzAnd RfWhen equal decline or close numerical value, even if the both positive and negative polarity of system
Voltage has been had descended to below alarm threshold, and the relay 103 does not work still.So the circuit can not realize above-mentioned situation
Alarm.
Fig. 2 shows the circuit theory diagrams of double unbalanced electric bridges.
As shown in Fig. 2 double unbalanced electric bridges are that two groups of resistance are set between the positive and negative busbar of straight-flow system.Wherein
First group of resistance includes resistance R201 and resistance R202, and second group of resistance includes resistance R203 and resistance R204, wherein resistance
The resistance that R201 resistance and resistance R204 resistance are R, resistance R202 and resistance R203 be R', R and R' value not
It is equal.During switch K switchings, R201 and R202 location swap can be regarded as.Sampling switch K is in difference respectively
The voltage at resistance Rj two ends during position, the Rz of equivalent resistance over the ground and Rf of positive and negative busbar can be calculated according to the voltage.
Double unbalanced electric bridges both positive and negative polarity grounding resistance on an equal basis decline in the case of, also can by Uj1, Uj2 (Uj1,
Uj2 is respectively the voltage at Rj two ends when K is allocated to the left side and the right in Fig. 2) detect, so as to make up the defect of bridge method.But
Double unbalanced electric bridges need to use two sets of circuits to toggle, and the electronic component that circuit is installed additional is excessive.
Based on above-mentioned situation, needing badly a kind of can effectively and reliably monitor the circuit of straight-flow system state of insulation.
The content of the invention
To solve the above problems, the invention provides a kind of D.C. isolation observation circuit, including：
Resistance switch unit, it includes at least three ends, wherein, first end and the positive pole of monitored straight-flow system connect
Connect, the second end is connected with the negative pole of the monitored straight-flow system, the resistance switch unit can be by first end and
The resistance between resistance and the second end and the 3rd end between three ends mutually switches；
First resistor, its one end is connected with the 3rd end of the resistance switch unit, and the other end is connected to ground；
First voltage measuring unit, it is connected to the positive and negative end of the monitored straight-flow system；
Second voltage measuring unit, it is connected to the first resistor two ends.
According to one embodiment of present invention, the second voltage measuring unit is changed to be connected to the resistance switch unit
The second end and the 3rd end between, for measuring the voltage between the second end and the 3rd end.
According to one embodiment of present invention, the resistance switch unit includes：
It is connected on second resistance and 3rd resistor between the first end of the resistance switch unit and the 3rd end；
The 4th resistance and the 5th resistance between the second end of told resistance switch unit and the 3rd end are connected on, its
Described in the 4th resistance it is equal with the resistance of the 3rd resistor, the 5th resistance is equal with the resistance of the second resistance；
The first switching switch in parallel with the 3rd resistor；
The second switching with the 4th resistor coupled in parallel is switched.
According to one embodiment of present invention, the first switching switch be changed to it is in parallel with the second resistance, described the
Two switching switches are changed to and the 5th resistor coupled in parallel.
According to one embodiment of present invention, the first switching switch and the described second switching switch include electronics relay
Device.
According to one embodiment of present invention, the first voltage measuring unit and second voltage measuring unit include voltage
Transformer.
Present invention also offers a kind of D.C. isolation monitoring method based on D.C. isolation observation circuit as described above, institute
The method of stating comprises the following steps：
First voltage and second voltage are obtained by first voltage measuring unit and second voltage measuring unit respectively；
After resistance switch unit carries out resistance switching, tertiary voltage is obtained by second voltage measuring unit；
According to the first voltage, second voltage and tertiary voltage, the positive and negative equivalent electric over the ground of monitored straight-flow system is calculated
The equivalent parallel value of resistance；
Judge whether the equivalent parallel value is less than preset alarm threshold value, and described be monitored directly is determined according to judged result
The D.C. isolation state of streaming system.
According to one embodiment of present invention, if the equivalent parallel value is less than preset alarm threshold value, it is determined that described
The D.C. isolation of monitored straight-flow system is abnormal, otherwise determines that the D.C. isolation of the monitored straight-flow system is normal.
According to one embodiment of present invention, if the equivalent parallel value is less than preset alarm threshold value, and persistently preset
Duration, it is determined that the D.C. isolation of the monitored straight-flow system is bad, otherwise determines the direct current of the monitored straight-flow system
Insulation is good.
According to one embodiment of present invention, the positive and negative equivalent resistance over the ground of monitored straight-flow system is calculated according to equation below
Equivalent parallel value：
Wherein, RzRepresent the equivalent resistance over the ground of monitored straight-flow system positive pole, RfRepresent monitored straight-flow system negative pole
Equivalent resistance, R over the groundz||RfRepresent the equivalent parallel value of the positive and negative equivalent resistance over the ground of monitored straight-flow system, R1Represent the second electricity
Resistance and the resistance of the 5th resistance, R2Represent 3rd resistor and the resistance of the 4th resistance, R0Represent the resistance of first resistor, UinRepresent
Voltage between monitored straight-flow system both positive and negative polarity, i.e. first voltage, Ua1Represent second voltage, Ua2Represent tertiary voltage.
The present invention comes real by the cycle detection to the switching of D.C. isolation observation circuit state and DC input voitage information
When monitoring equivalent resistance resistance over the ground, so as to judge the state of insulation of straight-flow system, prevent because the DC side ground connection of system and
Cause harm.Using Low-voltage Electronic switching device and single bridge circuit in the observation circuit that the present invention is provided, electricity is advantageously reduced
Road cost and the service life for extending circuit, so as to improve the dependable with function of circuit.
Meanwhile, the monitoring method that the present invention is provided realizes the insulating monitoring to straight-flow system using software control algorithm,
The investment of observation circuit hardware device is reduced, cost is saved.Meanwhile, used in the method that provides of the present invention it is default simultaneously
The Protection parameters threshold value for joining equivalent resistance over the ground can be set accordingly according to different application scenarios, so improve this
The versatility and reliability of invention.
Other features and advantages of the present invention will be illustrated in the following description, also, partly becomes from specification
Obtain it is clear that or being understood by implementing the present invention.The purpose of the present invention and other advantages can be by specification, rights
Specifically noted structure is realized and obtained in claim and accompanying drawing.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the accompanying drawing required in technology description to do simple introduction：
Fig. 1 is the schematic diagram of D.C. isolation observation circuit in existing balanced bridge method；
Fig. 2 is the schematic diagram of D.C. isolation observation circuit in existing pair of unbalanced electric bridge；
Fig. 3 is the schematic diagram of D.C. isolation observation circuit according to an embodiment of the invention；
Fig. 4 is equivalent circuit diagram of the D.C. isolation observation circuit according to an embodiment of the invention in first state；
Fig. 5 is the thevenin equivalent circuit figure of circuit shown in Fig. 4；
Fig. 6 is equivalent circuit diagram of the D.C. isolation observation circuit according to an embodiment of the invention in the second state；
Fig. 7 is the thevenin equivalent circuit figure of circuit shown in Fig. 6；
Fig. 8 is the flow chart of D.C. isolation monitoring method according to an embodiment of the invention.
Embodiment
Describe embodiments of the present invention in detail below with reference to drawings and Examples, how the present invention is applied whereby
Technological means solves technical problem, and reaches the implementation process of technique effect and can fully understand and implement according to this.Need explanation
As long as not constituting each embodiment in conflict, the present invention and each feature in each embodiment can be combined with each other,
The technical scheme formed is within protection scope of the present invention.
In addition, the step of the flow of accompanying drawing is illustrated can such as one group computer executable instructions department of computer science
Performed in system, and, although logical order is shown in flow charts, but in some cases, can be with different from herein
Order perform shown or described step.
Fig. 3 shows the schematic diagram for the D.C. isolation observation circuit that the present embodiment is provided.
As shown in figure 3, the direct current observation circuit that is provided of the present embodiment include resistance switch unit 301, first resistor R0,
First voltage measuring unit SV1 and second voltage measuring unit SV2.Wherein, resistance switch unit 301 includes three ends, its
First end 301a is connected with the positive pole of monitored straight-flow system, and the second end 301b and the negative pole of monitored straight-flow system connect
Connect, the 3rd end 301c is connected with first resistor R0 one end, the first resistor R0 other end is connected to ground.Resistance switch unit
301 can be by the resistance between first end 301a and the 3rd end 301c and the second end 301b and the 3rd end 301c
Between resistance mutually switch.It should be noted that in other embodiments of the invention, according to setting for actual circuit
Put, the port number that resistance switch unit 301 is included can also be other reasonable values, and the invention is not restricted to this.
From figure 3, it can be seen that in the present embodiment, resistance switch unit 301 includes：It is connected on first end 301a and
Second resistance R7 and 3rd resistor R8 between three end 301c, it is connected between the second end 301b and the 3rd end 301c
4th resistance R9 and the 5th resistance R10, and be connected in parallel on the first switching switch S1 at 3rd resistor R8 two ends and be connected in parallel on the 4th
The second switching switch S2 at resistance R9 two ends.
In the present embodiment, second resistance R7 is equal with the 5th resistance R10 resistance, is R1；3rd resistor R8 with
4th resistance R9 resistance is equal, is R2.The switch K used in existing pair of unbalanced electric bridge needs to use resistance to height
The device of pressure, which results in the cost of whole circuit is too high.Meanwhile, the switch K used in double unbalanced electric bridges is generally machinery
Relay, since it is desired that frequent switching, so causing the life-span of mechanical relay shorter.In the present embodiment, the first switching switch
The switchings of S1 and second switch S2 so monitors electricity using Low-voltage Electronic switching devices such as electronic relays compared to existing direct current
Road, the circuit that the present embodiment is provided can have longer service life and more intelligent type of drive, be conducive to whole
The practicality and accuracy of circuit.
When the first switching switch S1 disconnects and the second switching switch S2 closures, i.e. direct current observation circuit is in first state
When, the resistance between first end 301a and the 3rd end 301c is the resistance that second resistance R7 connects with 3rd resistor R8
Resistance, i.e. R1+R2, the resistance that the resistance between the second end 301b and the 3rd end 301c is the 5th resistance R10, i.e. R1。
When resistance switching circuit 301 carries out resistance switching, i.e., the first switching switch S1 closures and second switch switch S2 and broken
When opening, now direct current observation circuit is in the second state.Now, the first end 301a of resistance switching circuit 301 and the 3rd end
The resistance that resistance between portion 301c is second resistance R7, i.e. R1, between the second end 301b and the 3rd end 301c
Resistance is the resistance that the 4th resistance R9 connects with the 5th resistance R10, i.e. R1+R2。
It should be noted that in other embodiments of the invention, the first switching switch and the second switching switch also to set
Put in other rational positions, the such as first switching switch in parallel is at the two ends of second resistance, and the second switching switch in parallel is the 5th
The two ends of resistance, the invention is not restricted to this.
So, resistance switching circuit 301 carry out resistance switching be achieved that first end 301a and the 3rd end 301c it
Between resistance and the second end 301b and the 3rd end 301c between resistance mutual switching.
In addition, in figure 3, RzRepresent the equivalent resistance over the ground of monitored straight-flow system positive pole, RfRepresent monitored direct current system
The equivalent resistance over the ground of system negative pole.
It should be noted that in other embodiments in accordance with the invention, the first port of resistance switch unit and the 3rd
The resistance quantity between resistance quantity and second port and the 3rd port between port can also be carried out according to actual needs
Increase, the invention is not restricted to this.
As shown in figure 3, in the present embodiment, first voltage measuring unit SV1 is connected to the both positive and negative polarity of monitored straight-flow system
Two ends, for measuring the voltage between monitored straight-flow system both positive and negative polarity, the voltage can also regard resistance switch unit 301 as
First end 301a and the second end 301b between voltage.Second voltage measuring unit SV2 is connected to resistance switch unit
Between 301 the second end 301b and the 3rd end 301c, for measuring between the second end 301b and the 3rd end 301c
Voltage.In the present embodiment, first voltage measuring unit SV1 and second voltage measuring unit SV2 use voltage transformer, but this hair
Bright not limited to this.
It should be noted that in other embodiments in accordance with the invention, first voltage measuring unit SV1 and second voltage
Measuring unit SV2 can also be arranged on other rational positions, such as between the first end of resistance switch unit and the 3rd end,
Or the position such as two ends of first resistor, the invention is not restricted to this.
When the first switching switch S1 disconnects and the second switching switchs S2 closures, circuit illustrated in fig. 3 can be equivalent to
Circuit shown in Fig. 4.
As shown in figure 4, between the monitored straight-flow system both positive and negative polarity that now first voltage measuring unit SV1 measurements are obtained
Voltage Uin, the voltage is used as first voltage.Resistance switch unit the second end that second voltage measuring unit SV2 measurements are obtained with
Voltage U between 3rd endm1, the voltage is used as second voltage.So, the now voltage U at first resistor R0 two endsa1Can be with
Calculated and obtained according to equation below：
According to Thevenin's theorem, the circuit shown in Fig. 4 can be equivalent to circuit as shown in Figure 5.Wherein, equivalent resistance Ra1
And RbIt can be calculated and obtained according to equation below respectively：
Ra1=(R1+R2)||R1 (2)
Rb=Rz||Rf (3)
Voltage Uoc1It can be calculated and obtained according to equation below：
Now, according to Fig. 5 circuit and combination formula (2)~(4) can calculate and obtain Ua1, i.e.,：
When the first switching switch S1 is closed and the second switching switch S2 disconnects, circuit illustrated in fig. 3 can be equivalent to
Circuit shown in Fig. 6.
As shown in fig. 6, between the detected straight-flow system both positive and negative polarity that now first voltage measuring unit SV1 measurements are obtained
Voltage Uin, the voltage is first voltage.Resistance switch unit the second end that second voltage measuring unit SV2 measurements are obtained with
Voltage U between 3rd endm2, the voltage is used as tertiary voltage.So, the now voltage U at first resistor R0 two endsa2Can be with
Calculated and obtained according to equation below：
According to Thevenin's theorem, the circuit shown in Fig. 6 can be equivalent to circuit as shown in Figure 7.Wherein, equivalent resistance Ra2
And RbIt can be calculated and obtained according to equation below respectively：
Ra2=R1||(R1+R2) (7)
Rb=Rz||Rf (8)
Voltage Uoc2It can be calculated and obtained according to equation below：
Circuit and combination formula (7)~(9) according to Fig. 7 can calculate and obtain Ua2, i.e.,：
With reference to formula (5) and formula (10), then the positive and negative equivalent resistance over the ground for obtaining monitored straight-flow system can be calculated
Equivalent parallel value Rz||Rf, i.e.,：
From formula (11) if in as can be seen that just equivalent resistance and the negative equivalent electric over the ground over the ground of monitored straight-flow system
The resistance decrease of any one in resistance, can cause the two parallel value to reduce, and be reflected in first voltage measuring unit and second
On the measured value of voltage measurement unit, so as to realize the insulating monitoring to straight-flow system.
Based on above-mentioned insulating monitoring circuit, present invention also offers a kind of D.C. isolation monitoring method, Fig. 8 shows this reality
Apply the flow chart of this method in example.
As shown in figure 8, in the present embodiment, first in step S801, when direct current observation circuit is in first state, leading to
Cross first voltage measuring unit and second voltage measuring unit obtains voltage U between detected straight-flow system both positive and negative polarity respectivelyin
The voltage U of (i.e. first voltage) between resistance switch unit the second end and the 3rd endm1(i.e. second voltage).
Then in step S802, after resistance switch unit carries out resistance switching, i.e., DC System Monitoring is in second
During state, pass through the voltage U of second voltage measuring unit acquisition now between resistance switch unit the second end and the 3rd endm2
(i.e. tertiary voltage).
In step S803, according to the first voltage U of acquisitionin, second voltage Um1With tertiary voltage Um2, utilize formula
(11) the equivalent parallel value R of the positive and negative equivalent resistance over the ground of monitored straight-flow system is calculatedz||Rf。
In step S804, the positive and negative equivalent resistance over the ground for the monitored straight-flow system that judgment step S803 is obtained it is equivalent
Parallel value Rz||RfWhether preset alarm threshold value is less than.If equivalent parallel value Rz||RfAbove-mentioned condition is met, then in step S805
The middle D.C. isolation for judging monitored straight-flow system is abnormal, it is understood that there may be DC earthing phenomenon；Otherwise judge in step S806
The D.C. isolation of monitored system is normal.
In order that the monitoring result that must be obtained is relatively reliable, in other embodiments in accordance with the invention, judging to be supervised
Survey the equivalent parallel value R of the positive and negative equivalent resistance over the ground of straight-flow systemz||RfDuring with the size of preset alarm threshold value, it can also sentence
The equivalent parallel value of breaking Rz||RfWhether constantly it is less than preset alarm threshold value in preset duration, monitored system is judged with this
Whether the D.C. isolation of system is normal.The monitoring result caused by noise because of present in circuit so can be effectively eliminated to be forbidden
Really the problem of, so that obtained result is more accurate, reliable, improve the practicality of whole circuit.
As can be seen that the present invention to the switching of D.C. isolation observation circuit state and direct current by inputting electricity from foregoing description
Press the cycle detection of information, monitor equivalent resistance resistance over the ground in real time, so as to judge the state of insulation of straight-flow system, prevent because
Caused harm for the DC side ground connection of system.Low-voltage Electronic switching device and Dan Qiao are used in the observation circuit that the present invention is provided
Formula circuit, advantageously reduces circuit cost and extends the service life of circuit, so as to improve the dependable with function of circuit.
Meanwhile, the monitoring method that the present invention is provided realizes the insulating monitoring to straight-flow system using software control algorithm,
The investment of observation circuit hardware device is reduced, cost is saved.Meanwhile, used in the method that provides of the present invention it is default simultaneously
The Protection parameters threshold value for joining equivalent resistance over the ground can be set accordingly according to different application scenarios, so improve this
The versatility and reliability of invention.
Although disclosed herein embodiment as above, described content is only to facilitate understanding the present invention and adopting
Embodiment, is not limited to the present invention.Any those skilled in the art to which this invention pertains, are not departing from this
On the premise of the disclosed spirit and scope of invention, any modification and change can be made in the implementing form and in details,
But the scope of patent protection of the present invention, still should be subject to the scope of the claims as defined in the appended claims.
Claims (13)
1. a kind of D.C. isolation observation circuit, it is characterised in that including：
Resistance switch unit, it includes at least three ends, the second resistance that is connected between first end and the 3rd end and
3rd resistor, is connected on the 4th resistance and the 5th resistance between the second end and the 3rd end, with the 3rd resistor
First switching switch in parallel and the second switching switch with the 4th resistor coupled in parallel, wherein, the first end and quilt
The positive pole connection of straight-flow system is monitored, the second end is connected with the negative pole of the monitored straight-flow system, and the resistance is cut
Changing unit can be by the resistance between the first end and the 3rd end and the second end and the described 3rd
Resistance between end mutually switches, and the 4th resistance is equal with the resistance of the 3rd resistor, the 5th resistance
It is equal with the resistance of the second resistance；
First resistor, its one end is connected with the 3rd end of the resistance switch unit, and the other end is connected to ground；
First voltage measuring unit, it is connected to the positive and negative end of the monitored straight-flow system；
Second voltage measuring unit, it is connected to the first resistor two ends.
2. circuit as claimed in claim 1, it is characterised in that the second voltage measuring unit is changed to be connected to the resistance
Between the second end of switch unit and the 3rd end, for measuring the voltage between the second end and the 3rd end.
3. circuit as claimed in claim 1 or 2, it is characterised in that
It is described first switching switch be changed to it is in parallel with the second resistance, it is described second switch switch is changed to and the 5th resistance
It is in parallel.
4. circuit as claimed in claim 1 or 2, it is characterised in that the first switching switch and the described second switching switch
Including electronic relay.
5. circuit as claimed in claim 3, it is characterised in that the first switching switch and the described second switching switch include
Electronic relay.
6. the circuit as any one of claim 1,2,5, it is characterised in that the first voltage measuring unit and second
Voltage measurement unit includes voltage transformer.
7. circuit as claimed in claim 3, it is characterised in that the first voltage measuring unit and second voltage measuring unit
Including voltage transformer.
8. circuit as claimed in claim 4, it is characterised in that the first voltage measuring unit and second voltage measuring unit
Including voltage transformer.
9. circuit as claimed in claim 1 or 2, it is characterised in that first voltage measuring unit and the second voltage measurement
Unit includes voltage transformer.
10. a kind of D.C. isolation monitoring method based on circuit such as according to any one of claims 1 to 9, it is characterised in that
Comprise the following steps：
When the second switching that the first switching that first voltage measuring unit includes is switched off and second voltage measuring unit includes
During switch closure, first voltage and second voltage are obtained by first voltage measuring unit and second voltage measuring unit respectively；
After resistance switch unit carries out resistance switching, tertiary voltage is obtained by second voltage measuring unit；
According to the first voltage, second voltage and tertiary voltage, the positive and negative equivalent resistance over the ground of monitored straight-flow system is calculated
Equivalent parallel value；
Judge that whether the equivalent parallel value is less than preset alarm threshold value, and determine the monitored direct current system according to judged result
The D.C. isolation state of system.
11. method as claimed in claim 10, it is characterised in that
If the equivalent parallel value is less than preset alarm threshold value, it is determined that the D.C. isolation of the monitored straight-flow system is different
Often, otherwise determine that the D.C. isolation of the monitored straight-flow system is normal.
12. method as claimed in claim 10, it is characterised in that
If the equivalent parallel value is less than preset alarm threshold value, and continues preset duration, it is determined that the monitored direct current system
The D.C. isolation of system is bad, otherwise determines that the D.C. isolation of the monitored straight-flow system is good.
13. the method as any one of claim 10~12, it is characterised in that calculate monitored straight according to equation below
The equivalent parallel value of the positive and negative equivalent resistance over the ground of streaming system：
Wherein, RzRepresent the equivalent resistance over the ground of monitored straight-flow system positive pole, RfRepresent monitored straight-flow system negative pole over the ground
Equivalent resistance, Rz||RfRepresent the equivalent parallel value of the positive and negative equivalent resistance over the ground of monitored straight-flow system, R1Represent second resistance and
The resistance of 5th resistance, R2Represent 3rd resistor and the resistance of the 4th resistance, R0Represent the resistance of first resistor, UinRepresent first
Voltage, that is, be monitored the voltage between straight-flow system both positive and negative polarity, Ua1Represent the first switching included in first voltage measuring unit
Switch off and during second voltage measuring unit includes the second switching switch closure first resistor two ends voltage, Ua2Represent
The second switching switch that the first switching switch closure and second voltage measuring unit that first voltage measuring unit includes include is disconnected
The voltage at first resistor two ends when opening.
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| CN104535850B (en) * | 2014-12-09 | 2019-01-04 | 国家电网公司 | A kind of D.C. isolation monitoring device |
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| RU2739386C2 (en) * | 2019-01-29 | 2020-12-23 | Федеральное государственное казенное военное образовательное учреждение высшего образования "Военный учебно-научный центр Военно-Морского Флота "Военно-морская академия им. Адмирала Флота Советского Союза Н.Г. Кузнецова" | Method for determination of insulation resistance reduction point |
| RU2736328C1 (en) * | 2019-12-12 | 2020-11-13 | Федеральное государственное казенное военное образовательное учреждение высшего образования "Военный учебно-научный центр Военно-Морского Флота "Военно-морская академия имени Адмирала флота Советского Союза Н.Г. Кузнецова" | Method for remote determination of insulation resistance reduction point in deenergised electric circuit |
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| CN111896854A (en) * | 2020-06-28 | 2020-11-06 | 杭州中恒电气股份有限公司 | Switching circuit and direct current system insulation detection device and method |
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