CN88201085U - Super accurate megger with short circuit protector - Google Patents
Super accurate megger with short circuit protector Download PDFInfo
- Publication number
- CN88201085U CN88201085U CN 88201085 CN88201085U CN88201085U CN 88201085 U CN88201085 U CN 88201085U CN 88201085 CN88201085 CN 88201085 CN 88201085 U CN88201085 U CN 88201085U CN 88201085 U CN88201085 U CN 88201085U
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- CN
- China
- Prior art keywords
- megger
- short circuit
- resistance
- measuring
- circuit protector
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- Measurement Of Resistance Or Impedance (AREA)
Abstract
The utility model discloses a super accurate megger with a short circuit protector, composed of an electric power converter, a voltage dividing resistor, a current sampling resistor, an integrated converter, a follower, a short circuit protector, etc. The measuring range of the megger is 1*10+[3] ohms to 1.999*10+[14] ohms. The utility model which has the advantages of simple circuit, little error, low cost, and convenient operation can not damage instruments when two measuring terminals contact and form short circuit. The megger is suitable for measuring the insulation resistance of electric appliances, particularly for measuring the resistance of electrostatic prevention products.
Description
The utility model belongs to high-resistance measurement instrument.
The regulation test voltage is 500 volts or bigger in the method for testing of majority state measurement anti-static product resistance in the world, and existing megger is when the test voltage of using more than 500 volts.Test lead just can damage instrument with high-pressure side in case contact the formation short circuit.This phenomenon is actually and is difficult to avoid, and brings inconvenience to the operator.The digital megger of domestic advanced person's HZ2511 type adopts two-stage amplifier, and one-level is a micro current amplifier, and another level is an active filter.The measurement range of this type megger is 2 * 10
5Ohm～199 * 10
14Ohm.Measuring error is big, and error range is 3%～10%, the reading instability, and megger is usually used in testing the resistance value of anti-static product, and the resistance value of most of anti-static product is 10
4Ohm～10
9In ohm scope, and the measurement lower limit of HZ2511 type megger is 2 * 10
5Ohm obviously just can not meet the demands.If use HZ2511 type megger to measure the resistance of anti-static product, when measuring 10
5During the following resistance of ohm, must make troubles to surveying work with other ohmmeter replacement HZ2511 type megger.
In view of the problem that above-mentioned prior art exists, the utility model task is a kind of precision height of design, the new digital formula megger of short-circuit protection is arranged that its measurement range is 1 * 10
3Ohm is to 1.999 * 10
14Ohm, measuring error is little, and error range is 0.5%～5%.
The megger that the utility model provides mainly is made up of electric power conversion apparatus, voltage divider resistance, current sampling resistor, follower, A/D double integral transformation device and short-circuit protection etc.By Fig. 2,3,4 circuit that connect into, as shown in Figure 1.This circuit bank is contained in the hexahedral metal shell, on panel, draws two terminals of measured resistance Rx, also have liquid crystal display on the panel in order to show the measured resistance value.
Referring to Fig. 2, Ro flows through the sample resistance of measured resistance Rx electric current as detection, Ro＜＜Rx, R among the figure
1And R
2As the divider resistance of measuring voltage U, take out the voltage signal at resistance R x two ends and the current signal that flows through resistance R x, deliver to A/D double integral transformation device.Demonstrate resistance value through A/D conversion back on liquid crystal display, result displayed is not subjected to the influence of change in voltage.Because the displayed value of double integral transformation device A/D and input voltage V
1NWith reference voltage V
RefFollowing relation is arranged:
Displayed value=(V
1N)/(V
Ref)
From the visible V of Fig. 2
Ref=(Ro)/(Ro+Rx) U=(Ro)/(Rx) U
V
1N＝ (R
2)/(R
1+R
2) U
Displayed value=(V then
1N)/(V
Ref)=(R
2)/((R
1+ R
2) R
0) Rx
Be that displayed value is directly proportional with Rx, and only by R
1, R
2, four resistance decisions of Ro and Rx.Irrelevant with labile factor such as test voltage, as long as suitably adjust R
1, R
2And Ro, just can make the very high digital megger of precision.The reference voltage V of double integral transformation device A/D
RefInput resistance is approximately 10
9Ohm, when measuring high resistance, can not be V
RefDirectly be connected on the current sampling resistor Ro, must adopt the high follower Q of one-level input impedance, as shown in Figure 3.
Another characteristics of the utility model megger are that short-circuit protection is arranged, and see Fig. 4.When measuring resistance Rx two ends p-wire contacts the formation short circuit, the A point voltage is a high-voltage pulse, after time-delay element T time-delay, the B point voltage will rise gradually, follower Q output voltage also rises gradually, when this voltage rises to certain value, will make the on-off element conducting, and make test voltage drop to below the unlikely damage follower input threshold voltage.
Through the check of quantitative study unit and units concerned's probationary certificate.The utility model megger good stability, measuring accuracy height.Easy to operate, operating personnel needn't worry the contact of two test leads and damage instrument.Because circuit is simple, also has the low advantage of cost simultaneously.The utility model megger is applicable to the insulation resistance of measuring electric equipment products, is specially adapted to measure the resistance of anti-static product.
Fig. 1 represents the circuit general assembly synoptic diagram of the utility model megger.S represents power conversion among the figure, and P represents display device.
Fig. 2 represents test philosophy figure.Rx is a measured resistance among the figure.Ro is a current sampling resistor, R
1And R
2Be divider resistance, U is a supply voltage, V
RefBe reference voltage, V
1NBe input voltage, A/D is the double integral transformation device.
Fig. 3 is expressed as and improves V
RefThe one-level follower Q that holds input impedance and set up.
Fig. 4 represents short-circuit protection circuit figure.T is a time-delay element among the figure, and K is an on-off element, and its control end g receives the output terminal of follower Q.
Claims (2)
1, a kind of digital megger is characterized in that having the proving installation of being made up of current sampling resistor, voltage divider resistance and double integral transformation device.
2, by the described megger of claim 1, it is characterized in that having the short-circuit protection of forming by time-delay element, on-off element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88201085 CN88201085U (en) | 1988-02-05 | 1988-02-05 | Super accurate megger with short circuit protector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88201085 CN88201085U (en) | 1988-02-05 | 1988-02-05 | Super accurate megger with short circuit protector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN88201085U true CN88201085U (en) | 1988-11-23 |
Family
ID=4836372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 88201085 Withdrawn CN88201085U (en) | 1988-02-05 | 1988-02-05 | Super accurate megger with short circuit protector |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN88201085U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101825661A (en) * | 2010-05-18 | 2010-09-08 | 宁波大学 | Instrument for dynamically measuring high resistance |
| CN108594020A (en) * | 2018-04-27 | 2018-09-28 | 陈德文 | The highly sensitive conductance of number display and high resistance measurement measuring circuit and method |
| CN113252988A (en) * | 2021-07-05 | 2021-08-13 | 湖南亿能电子科技有限公司 | Handheld parameter tester and parameter testing method |
-
1988
- 1988-02-05 CN CN 88201085 patent/CN88201085U/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101825661A (en) * | 2010-05-18 | 2010-09-08 | 宁波大学 | Instrument for dynamically measuring high resistance |
| CN101825661B (en) * | 2010-05-18 | 2011-12-28 | 宁波大学 | Instrument for dynamically measuring high resistance |
| CN108594020A (en) * | 2018-04-27 | 2018-09-28 | 陈德文 | The highly sensitive conductance of number display and high resistance measurement measuring circuit and method |
| CN108594020B (en) * | 2018-04-27 | 2020-05-05 | 陈德文 | Digital display high-sensitivity conductance and high-resistance measuring circuit and method |
| CN113252988A (en) * | 2021-07-05 | 2021-08-13 | 湖南亿能电子科技有限公司 | Handheld parameter tester and parameter testing method |
| CN113252988B (en) * | 2021-07-05 | 2021-10-26 | 湖南亿能电子科技有限公司 | Handheld parameter tester and parameter testing method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |