Current transformer half-wave current mapping fault detection method
Technical field
The present invention relates to a kind of current transformer in half-wave current down conversion error detecting methods, belong to electric-power metering current transformer detection technique field.
Background technology
The different model that different manufacturers is produced and the current transformer of different batches, the magnetic property of iron core is all incomplete same, and remanent magnetism is also inequality to the influence of current transformer error.It possibly be that DC component is arranged in the primary current that a kind of of strong remanent magnetism appears in operating current transformer, makes the iron core magnetic saturation, causes the equivalent magnetoconductivity of iron core to reduce, and error will be significantly to negative reverse moving.DC component can be studied in the mapping fault under the half-wave current through current transformer the influence of current transformer error.The checkout equipment that is used at present current transformer both at home and abroad is the interchange full-wave type; The calibrating wiring diagram of the conventional voltage transformer (VT) calibrating wiring diagram of JJG1021-2007 " current transformer vertification regulation " regulation is as shown in Figure 1, but it can't detect in the mapping fault under the half-wave current current transformer.
Detect in order to solve the mapping fault of current transformer under half-wave current, study a kind of current transformer in half-wave current down conversion error detecting methods to changing above-mentioned situation, significant.
Summary of the invention
The objective of the invention is; Be the interchange full-wave type in order to solve the checkout equipment that is used for current transformer at present both at home and abroad; The problem that can't detect in the mapping fault under the half-wave current current transformer; How to utilize existing equipment to detect current transformer, the invention provides a kind of current transformer in half-wave current down conversion error detecting methods in half-wave current down conversion error.
Technical scheme of the present invention is; On the basis of existing current transformer calibrating circuit, use the diode of 2 forward conduction electric currents greater than the current transformer rated current, one positive one instead connects with two bench teat article current transformers respectively; Form a positive half-wave current transformer and a negative half-wave current mutual inductor; Half-wave current mutual inductor parallel connection with two symmetries is combined into the full-wave electric current mutual inductor and carries out error measure, records the error that error is the half-wave current mutual inductor.
Current transformer has at the major equipment that half-wave current down conversion error detecting methods adopts: the accurate current transformer of a station symbol (0.02 grade), a mutual-inductor tester (2 grades), a current capacity case (3 grades), 2 forward conduction electric currents are greater than the diode of current transformer rated current.
Current transformer is as shown in the figure in the wiring of the detection of half-wave current down conversion error, and promptly two are tried current transformer CT
X1, CT
X2Secondary coil parallel connection, the difference testing current end K of a termination mutual-inductor tester, an end meet the working current test lead T of mutual-inductor tester through current capacity case Z
X2 forward conduction electric currents are greater than the diode D of current transformer rated current
1, D
2, one positive one instead connects D with two bench teat article current transformers respectively
2Positive pole connects by examination current transformer CT
X2Secondary coil one end, D
2Negative pole connects current lifting device one end; D
1Negative pole connects by examination current transformer CT
X1Secondary coil one end, D
1Positive pole and D
2And ally the communists and connect current lifting device; Standard mutual inductor CT
0Primary winding one termination current lifting device, the other end and two are linked by examination current transformer primary winding parallel connected end; Standard mutual inductor CT
0The working current test lead T of secondary coil one termination mutual-inductor tester
0, the other end and two parallel connected end by examination Current Transformer Secondary coil link; Mutual-inductor tester another difference testing current end D ground connection.
Requirement by the relevant rules of current transformer detects, and the steps include:
(1) limited load in the selection;
(2) by rules requirement up-flow, respectively in the upper limit load error of 1%, 5%, 20%, 100%, 120% measuring current mutual inductor of rated current;
(3) electric current is reduced to 0;
(4) select limited load down;
(5) by rules requirement up-flow, respectively in the lower limit load error of 1%, 5%, 20%, 100% measuring current mutual inductor of rated current;
(6) electric current is reduced to 0;
(7) accomplish the calibrating of this current transformer.
The invention has the beneficial effects as follows; Detect current transformer when half-wave current down conversion error; Use 2 forward conduction electric currents instead to connect with 2 bench teat article current transformers respectively greater than the diode one positive of current transformer rated current; Form a positive half-wave current transformer and a negative half-wave current mutual inductor; Constitute the detection line of current transformer, utilize current transformer calibration equipments such as existing interchange current lifting device, standard current transformer, mutual-inductor tester, Burden box, can realize the detection of current transformer in half-wave current down conversion error in half-wave current down conversion error.Have that method is succinct, economy, science, practicality, workable, low cost and other advantages.
The present invention is applicable to the anti-DC component metering accuracy of current transformer field of measuring technique.
Description of drawings
Fig. 1 is that the conventional current mutual inductor detects wiring diagram;
Fig. 2 is that the half-wave current transformer error detects wiring diagram;
Symbol among the figure: CT
0It is standard current transformer; CT
xIt is the test specimen current transformer; CT
X1It is #1 test specimen current transformer; CT
X2It is #2 test specimen current transformer; Z is the current transformer Burden box; D
1It is the #1 diode; D
2It is the #2 diode; T
0, T
XIt is mutual-inductor tester working current test lead; K, D are mutual-inductor tester difference testing current ends.
Embodiment
Below in conjunction with accompanying drawing the present invention is elaborated.
The first step: setup test equipment
The accurate current transformer of one station symbol (0.02 grade), a mutual-inductor tester (2 grades), a current capacity case (3 grades), 2 forward conduction electric currents are greater than the diode of current transformer rated current, two tested current transformers.
Second step: carry out wiring by Fig. 2 mode of connection;
Tried current transformer CT with two
X1, CT
X2Secondary coil parallel connection, the difference testing current end K of a termination mutual-inductor tester, an end meet the working current test lead T of mutual-inductor tester through current capacity case Z
X2 forward conduction electric currents are greater than the diode D of current transformer rated current
1, D
2, one positive one instead connects D with two bench teat article current transformers respectively
2Positive pole connects by examination current transformer CT
X2Secondary coil one end, D
2Negative pole connects current lifting device one end; D
1Negative pole connects by examination current transformer CT
X1Secondary coil one end, D
1Positive pole and D
2And ally the communists and connect current lifting device; Standard mutual inductor CT
0Primary winding one termination current lifting device, the other end and two are linked by examination current transformer primary winding parallel connected end; Standard mutual inductor CT
0The working current test lead T of secondary coil one termination mutual-inductor tester
0, the other end and two parallel connected end by examination Current Transformer Secondary coil link; Mutual-inductor tester another difference testing current end D ground connection.
The 3rd step: the requirement by JJG1021-2007 " current transformer vertification regulation " is examined and determine trying current transformer;
(1) limited load in the selection;
(2) by rules requirement up-flow, respectively in the upper limit load error of 1%, 5%, 20%, 100%, 120% measuring current mutual inductor of rated current;
(3) electric current is reduced to 0;
(4) select limited load down;
(5) by rules requirement up-flow, respectively in the lower limit load error of 1%, 5%, 20%, 100% measuring current mutual inductor of rated current;
(6) electric current is reduced to 0;
(7) accomplish the calibrating of this current transformer.