CN109782106A - A kind of DC system earth fault lookup device and method - Google Patents
A kind of DC system earth fault lookup device and method Download PDFInfo
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- CN109782106A CN109782106A CN201910011949.4A CN201910011949A CN109782106A CN 109782106 A CN109782106 A CN 109782106A CN 201910011949 A CN201910011949 A CN 201910011949A CN 109782106 A CN109782106 A CN 109782106A
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- ground fault
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Abstract
The invention discloses a kind of DC system earth faults to search point-score, and refoulement road recognizes ground fault, after determining the secondary circuit to break down, then by branch identification ground fault;It was found that ground fault immediately treats.The method for recognizing ground fault are as follows: multimeter is serially connected in one pole of failure switch or control insurance both ends by the extremely short envelope that the branch switch of secondary circuit or control are insured to non-failure;One end of the test resistance that resistance value is R is connected to a unearthed pole, the other end is connect with ground wire and earth fault forming circuit;Switch or control insurance are disconnected, the reading of multimeter is observed and record;It is then turned off one end of test resistance ground connection, observes and record the reading of multimeter again, if the reading difference value twice of multimeter is suitable with the electric current for flowing through test resistance calculated, determines that ground fault occurs.The present invention can take segmentation to find the method for processing searching grounding point, searching and eliminating ground fault in non-stop-machine situation;It is simple and easy to do.
Description
Technical field
The present invention relates to a kind of grounding fault device and methods more particularly to a kind of DC system earth fault to search
Device and method belongs to high and low voltage electric distribution maintenance technology field.
Background technique
DC control circuit distribution is wide in switchgear house, and path is complicated, and exposed parts are more.It is easy the shadow by outside environmental elements
It rings, under the effect of the undesirable elements such as humidity, dust, leads to the reduction of DC network dielectric level, in some instances it may even be possible to insulation damages occur
And it is grounded.It is all grounded if it is positive and negative the two poles of the earth, DC loop short trouble occurs, cause the switch trip in circuit or fuse disconnected,
The direct current system of corresponding portion will be caused to have a power failure, protection system loses protective effect.It is grounded if it is a wherein pole, direct current system
It continues to run, this is dangerous abnormal situation.If protective loop is again with other one point earths, breaker will occur
Mistrip causes heavy economic losses to production.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of DC system earth faults to search device and method.
In order to solve the above technical problems, the technical solution adopted by the present invention is that:
A kind of DC system earth fault lookup point-score, comprising the following specific steps
Step 1: refoulement road recognizes ground fault: it is made of step in detail below:
Step 1-1: the polarity of ground fault occurs for judgement: the branch switch of secondary circuit or control are insured to a pole of non-failure
Multimeter is serially connected in one pole of failure switch or control insurance both ends by short envelope;
Step 1-2: an end of the test resistance that resistance value is R is connected to a unearthed pole, the other end is connect with ground wire, and ground connection
Fault point forming circuit;
Step 1-3: the electric current for flowing through test resistance: i=220/R is calculated;
Step 1-4: identification ground fault: switch or control insurance are disconnected, the reading of multimeter is observed and record;It is then turned off survey
The one end for trying resistance eutral grounding, observes again and records the reading of multimeter, if the difference value of reading twice of multimeter and step 3
The electric current that test resistance is flowed through in calculating is suitable, then determines that ground fault occurs, turn to step 2;Otherwise determine that there is no ground connection
Failure.
Step 2: recognizing ground fault by branch: according to operation part after first signal and indicator light part, first outdoor section
The sequence of indoor section afterwards, before guaranteeing disconnected branches terminal, under the premise of branch cannot open a way, gradually disconnected branches circuit end
Son recognizes whether that there are ground faults using step 1-4 the method;If it find that ground fault, turns to step 3 and otherwise turns
To step 4;
Step 3: processing ground fault;
Step 4: closing the branch-path terminal of step 2 disconnection.
Further, the resistance value of the test resistance is 44K Ω.
Further, the precision of the multimeter is the 1/20000 of range.
Having the technical effect that acquired by by adopting the above technical scheme
1, the present invention can search in non-stop-machine situation and eliminate ground fault;
2, the present invention takes segmentation to find the method for processing to search grounding point, eliminates the hidden danger of equipment.
Detailed description of the invention
The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
Fig. 1 is flow chart of the invention;
Wherein: 1, multimeter 2, earth fault 3, short envelope line 4, test resistance.
Specific embodiment
Embodiment 1:
A kind of DC system earth fault lookup point-score, comprising the following specific steps
Step 1: refoulement road recognizes ground fault: it is made of step in detail below:
Step 1-1: the polarity of ground fault occurs for judgement: the branch switch of secondary circuit or control are insured to a pole of non-failure
Multimeter is serially connected in one pole of failure switch or control insurance both ends by short envelope;
Step 1-2: an end of the test resistance that resistance value is R is connected to a unearthed pole, the other end is connect with ground wire, and ground connection
Fault point forming circuit;
Step 1-3: the electric current for flowing through test resistance: i=220/R is calculated;
Step 1-4: identification ground fault: switch or control insurance are disconnected, the reading of multimeter is observed and record;It is then turned off survey
The one end for trying resistance eutral grounding, observes again and records the reading of multimeter, if the difference value of reading twice of multimeter and step 3
The electric current that test resistance is flowed through in calculating is suitable, then determines that ground fault occurs, turn to step 2;Otherwise determine that there is no ground connection
Failure.
Step 2: recognizing ground fault by branch: according to operation part after first signal and indicator light part, first outdoor section
The sequence of indoor section afterwards, before guaranteeing disconnected branches terminal, under the premise of branch cannot open a way, gradually disconnected branches circuit end
Son recognizes whether that there are ground faults using step 1-4 the method;If it find that ground fault, turns to step 3 and otherwise turns
To step 4;
Step 3: processing ground fault;
Step 4: closing the branch-path terminal of step 2 disconnection.
Further, the resistance value of the test resistance is 44K Ω.
Further, the precision of the multimeter is the 1/20000 of range.
Prepare the resistance of a 44K Ω, 4 Semi-digital multimeters and several instrument clips with line.With with line
An extremely short envelope of non-failure is insured in the branch switch of secondary circuit or control by instrument clip, and multimeter gear is beaten at 10A grades
On, multimeter robust is serially connected in one pole of failure switch or control insurance two with the instrument clip of test pencil line or belt line
End.
One end of 44K Ω resistance is connected to a unearthed pole, the other end is connect with ground wire (see figure) and earth fault
Forming circuit, can be calculated: I=U/R=220V/44K Ω=5mA.The electric current for flowing through resistance is 5mA, and relay coil hinders at present
10,000 or more, action current malfunctions value in 21mA, the electric current deficiency of 5mA.Disconnect switch or control insurance, observation ten thousand
With the reading of table, record reading.It is then turned off one end of the resistance eutral grounding of 44K Ω, whether the reading for observing multimeter has 5mA's
Variation.Resistance eutral grounding end is repeated several times ground connection, if the reading of multimeter is unchanged, illustrates that secondary control loop insulation is good,
Ground fault does not occur.Next secondary branch is searched by the method for same short sealing switch again, if the reading of multimeter exists
Change in the range of 5mA, illustrates that the control loop has the failure of ground connection, then the range shorter for searching grounding point can be arrived this
In a secondary control loop.
According to the method that the schematic diagram in the circuit takes segmentation to find processing, according to the content of step 4, branch is gradually disconnected
Road loop terminals (before guaranteeing disconnected branches terminal, branch cannot open a way), with operation part after first signal and indicator light part, first
Indoor section is principle after outdoor section.Should be short as far as possible in break time, no matter circuit should close whether ground connection.It is a certain when finding
When branch-path is grounded, grounding point should be found out in time and handled.
Since test DC earthing electric current is in milliampere grade, to guarantee measuring accuracy, four halves are used in actually searching
Word multimeter.In the display board of digital instrument, three and half mean 3 and 1/2nd digital multimeter, maximum display 1999,
Also known as three and half, it is partly the meaning 1/2nd of half, four and half precision are higher than three that it is from 1 to 9 that three representatives, which have three digits,
Half, principle is identical as three and half;Three and half precision can be to 1/2000, three to 1/1000;Four and half maximums can show 19999 energy
1/10000 is arrived to 1/20000, four.
Claims (3)
1. a kind of DC system earth fault searches point-score, it is characterised in that: comprising the following specific steps
Step 1: refoulement road recognizes ground fault: it is made of step in detail below:
Step 1-1: the polarity of ground fault occurs for judgement: the branch switch of secondary circuit or control are insured to a pole of non-failure
Multimeter is serially connected in one pole of failure switch or control insurance both ends by short envelope;
Step 1-2: an end of the test resistance that resistance value is R is connected to a unearthed pole, the other end is connect with ground wire, and ground connection
Fault point forming circuit;
Step 1-3: the electric current for flowing through test resistance: i=220/R is calculated;
Step 1-4: identification ground fault: switch or control insurance are disconnected, the reading of multimeter is observed and record;It is then turned off survey
The one end for trying resistance eutral grounding, observes again and records the reading of multimeter, if the difference value of reading twice of multimeter and step 3
The electric current that test resistance is flowed through in calculating is suitable, then determines that ground fault occurs, turn to step 2;Otherwise determine that there is no ground connection
Failure;
Step 2: recognizing ground fault by branch: according to operation part after first signal and indicator light part, first outdoor section rear chamber
The sequence of inner part, before guaranteeing disconnected branches terminal, under the premise of branch cannot open a way, gradually disconnected branches loop terminals, are adopted
Recognize whether that there are ground faults with step 1-4 the method;If it find that ground fault, turns to step 3 and otherwise turns to step
Rapid 4;
Step 3: processing ground fault;
Step 4: closing the branch-path terminal of step 2 disconnection.
2. DC system earth fault according to claim 1 searches point-score, it is characterised in that: described
The resistance value of test resistance is 44K Ω.
3. DC system earth fault according to claim 1 searches point-score, it is characterised in that: further, the general-purpose
The precision of table is the 1/20000 of range.
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CN201910011949.4A CN109782106B (en) | 2019-01-07 | 2019-01-07 | Direct current system ground fault searching device and method |
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