JB/T 5809-1991 Test method for cut-off current of vacuum contactor JB/T5809-1991 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T5809-91
Test Method for Cut-off Current of Vacuum Contactor
Published on 199110-15
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on 199210-01
Mechanical Industry Standard of the People's Republic of China
Test Method for Cut-off Current of Vacuum Contactor
1 Subject Content and Scope of Application
This standard specifies the test method for cut-off current of vacuum contactor. This standard is applicable to the test of cut-off current of vacuum contactor. JB/T5809-91
This standard is also applicable to the cut-off current test of vacuum switch tube (vacuum interrupter) and vacuum contact material used in contactor. Reference Standards
GB8170 Digital Rounding Rules
3·Terms and Codes
Vacuum Contactor Cut-off Current—When interrupting a small AC current, the arc goes out before the current reaches the natural zero point because the metal vapor generated by the vacuum switch tube contacts of the vacuum contactor is not enough to maintain the arc. The current suddenly drops to zero, and the current value at the moment the arc goes out is called the vacuum contactor's cut-off current, codenamed I. . The cut-off current value of the vacuum contactor is generally determined by the vacuum contact material.
Principle and Device
There are generally two methods for testing vacuum contactors: direct and indirect. This standard adopts an oscillation circuit and a peak indirect sampling method, named the peak oscillation circuit method.
4.1 Principle
Figure 1 is the main circuit principle circuit diagram of the test device used in this method K
Figure 1 · Main circuit principle circuit diagram
Z-—air core reactor;
C—ceramic capacitor,.R. current limiting resistor,
R, sampling resistor, K, a pair of main contacts of the tested contactor; T—adjustable transformer
After the contactor K is disconnected, the current damping oscillation is generated in the circuit composed of L-R-R,-C from the moment the arc between the contacts is extinguished. The maximum amplitude of the oscillation voltage U is measured on R, and I is measured using a peak voltage meter. =U./R, I. is close to the cut-off current value Ia.4.2 Device
Approved by the Ministry of Machinery and Electronics Industry on October 15, 1991 and implemented on October 1, 1992
The block diagram of the test device used in this method is shown in Figure 21
JB/T580991
Figure 2 Device Block Diagram
1-Digital Peak Voltage Meter;
2-Microcomputer System
4.2.1, Digital Peak Voltage Meter
The digital peak voltage meter is the key component of this device, which delivers the measured U. value to the microcomputer system. 4.2.2 Microcomputer System
The microcomputer system performs two functions, one is to control the on and off of the vacuum contactor under test at a certain frequency, and the other is to receive the output from the peak voltage meter. Divide the peak voltage measured by the peak voltmeter by the sampling resistance value to obtain the cut-off current value, and save the cut-off current value each time the contactor is disconnected. After data processing, print out. 5 Test conditions
The test current should be selected when the AC peak value is slightly greater than the maximum cut-off current value of the vacuum contactor under test. This method uses an AC current effective value of 10A ± 10%; an AC voltage effective value of 120V ± 10%: a wave impedance of 2.5~3kQ; a switching frequency of 600 times/h; each phase is tested separately, and the number of measurements is not less than 1000 times.
6 Sample preparation
6.1 The sample is a qualified product of the vacuum contactor. 6.2 The cut-off current test of the vacuum contact material and the vacuum switch tube is assembled on the corresponding vacuum contactor. 7 Test procedure
7.1 Connect the vacuum contactor to the test equipment circuit; 7.2 Turn on the machine;
7.3 Pre-switch for more than 50 times under the test voltage and current; 7.4 Pre-set the microcomputer, including: total number of on-off times, sampling resistance value, peak voltage meter range, number of block storage times, number of print copies, etc.;
7.5 After testing the preset total number of on-off times, the microcomputer system automatically prints out the cut-off current value measured at each break, as well as the maximum cut-off current value, the average cut-off current and the cut-off current cumulative probability distribution table; 7.6
JB/T5809-91
The microcomputer automatically stops after printing the preset number of copies. 8 Data processing
"Average cut-off current: determined by formula (1). 8.1
Where:
Tce-average cut-off current. A;
-total number of preset on-off times;
I-cut-off current value measured at each disconnection, A. 8.2 Standard deviation of cut-off current: determined by formula (2). (en-,)
Where,
Standard deviation of cut-off current, A.
8.3 Maximum cut-off current
The microcomputer compares the cut-off current value measured at each disconnection with the Icp+4o value. (1)
For all I≤Ic+4o The data is valid, otherwise it is discarded. After such a comparison, the maximum value is selected from the valid cut-off current data as the maximum cut-off current value.
9 Error
9.1 The standard error of the cut-off current average value is determined by formula (3). ObzxZ.net
Where:
die,—standard error of the cut-off current average value, A. 9.2 The maximum cut-off current error is 2%.
Test report
The test report should include the following contents:
Name of the test unit;
+Name, model, specification and manufacturer name of the test product; b.
Name of the testing unit:
Signature of the tester;| |tt||Test date;
Test conditions (test voltage, current);
Maximum cut-off current value and average value of test results; attached with printed records.
Oscillating current in the circuit
JB/T5809-91
Appendix A
I. Error caused by Ice
(reference)
According to the formula of the oscillation process, the oscillation current formula is: i=Iie-*sin(ot-0)
Where: i.-
-Oscillating current, A;
-Maximum amplitude of oscillation current, A;
-Attenuation coefficient, 1/ s:
Oscillating angular velocity, rad/s;
Time from the moment of arc extinction, S: t
9Initial phase, rad.
This test method uses a peak voltmeter to measure the U. value from R, and then obtains I. through I,=U_/R, and uses the Im value to approximate the cut-off current Ic value.
T. The theoretical error between Ic and Icp is derived from the formula: =Vi+n
Where: I cut-off current, A;
Deviation current component, A.
And I, is related to the basic parameters of the main circuit, and the formula is: I, = Bl, + βcU. + CarU.
Wherein,
Capacitance in the main circuit, F;
Voltage on the capacitor at the moment of arc extinction, V. (A2)
In order to estimate the deviation between I. and Icp, the parameters of the components in the circuit selected by this method are substituted, where U. is not a constant, and the peak value of the power supply voltage is substituted. The calculation results are shown in Table A. Table A Estimation of deviation between I. and Icp (L=38mH, C=0.0047μF, R=100, U=170V)I
JB/T5809-91
Continued Table A
It can be seen from the table that the deviation of using I. value instead of Ie value can be ignored. A=I. I
B1 Basic components in the oscillation circuit
JB/T5809-91
Appendix B
Selection of component parameters in the oscillation circuit
(Reference)
There are three basic components in the oscillation circuit: inductor L, capacitor C and resistor R. B2 Basis for selection of component parameters
The selection of component parameters needs to take into account the nature of the load carried by the vacuum contactor; the natural oscillation frequency of the oscillation circuit is limited by the bandwidth of the peak voltage meter and the requirements of the starting conditions. B2.1 This method takes into account that the objects controlled by the vacuum contactor are induction motors, and the wave impedance of the induction motor is generally between 1 and 3k2.
B2.2 According to formulas (A2) and (A3) in Appendix A, in order to reduce the deviation of the Icr value, the capacitor C should be selected as small as possible, so that the I value is very small, and the I. value is close to the Iei value. B2.3 The inductance and capacitance selected in the circuit are also limited by the inherent oscillation frequency of the circuit not being greater than the bandwidth of the peak voltage meter. This method uses the SFD-2 digital peak voltage meter with a bandwidth of 100kHz. B2.4, in order to meet the requirements of the oscillation circuit start-up, the selection of resistance R must meet R<2
B3 Actual component parameters
The actual component parameters selected in this method are inductance L of 38mH, capacitance C of 0.0047μF, and resistance R of 1002. Additional notes:
This standard is proposed and managed by the Shanghai Electric Science Research Institute of the Ministry of Machinery and Electronics Industry. This standard is drafted by the Shanghai Electric Science Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Bu Jinxin and He Qingtai. 6
People's Republic of China
Mechanical Industry Standard
Test Method for Cut-off Current of Vacuum Contactor
JB/T5809-91
Edited and published by the Standardization Research Office of the First Equipment Department of the Mechanical and Electronic Industry Ministry of Machinery and Electronics Industry
(Xiangtan City, Hunan Province)
Printed by Xiangtan Electric Motor Factory Printing Plant
Format 880×12301/16
First edition in July 1992
Sheet 5/8
3. Number of words 11000
First printing in July 1992
Printing number DB711
Price 2.00 yuan
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