1、Working principle of leakage protector

Leakage protector mainlypackageIncluding detection components(Zero sequencecurrentmutual inductor)Intermediate stage(includingamplifier, comparator, release, etc)Execution components(main switch)And several parts such as experimental components.

Schematic diagram of the working principle of the leakage protector in a three-phase four wire power supply system.TAFor zero sequencecurrentTransformer,QSMain switch,SBFor the experimental button.

According to Kirchhoff's law, when the protected circuit is working normally and there is no leakage or electric shock, it can be concluded thatTAOnce on the sidecurrentThe phasor sum is equal to zero. That is: like thisTAThe secondary side does not generate induced electromotive force, the leakage protector does not operate, and the system maintains normal power supply.

When the protected circuit experiences leakage or someone is electrocuted, due to leakagecurrentThe existence, throughTAThe phasor sum of the current in each phase on the primary side is no longer equal to zero, resulting in leakage currentI.

Alternating magnetic flux appeared in the iron core. Under the action of alternating magnetic flux,TAThe secondary coil generates induced electromotive force, which leads to leakagetelecommunicationsProcess and compare through intermediate steps, and when the predetermined value is reached, energize the main switch shunt release coil to drive the main switchQSAutomatic tripping, cutting off faulty electricity, thus achieving protection.

The working principle of the leakage protector used for single-phase circuits and three-phase three wire systems is the same and will not be repeated.

2Rated leakage action of leakage protectorcurrentThe following three conditions should be met:

(1)To ensure personal safety, rated leakage actioncurrentIt should not exceed the safe current value for human body, with a maximum of 30mA being the safe current value for human body;
(2)In order to ensure the reliable operation of the power grid, the rated leakage actioncurrentShould avoid being too lowvoltageNormal leakage current of the power grid;

(3)In order to ensure the selectivity of multi-level protection, the rated leakage current of the next level should be less than the rated leakage current of the previous level, and the rated leakage current of each level should have a step difference1.2～2.5Twice.

*Grade leakage protector installed in power distributiontransformerlow pressureAt the side exit. The line protected at this level is long and prone to leakagecurrentWhen the rated leakage action current is relatively large and there is no complete multi-level protection, the maximum should not exceed100mAWhen equipped with comprehensive multi-level protection, the power grid with low leakage current is suitable for non rainy seasons75mAThe rainy season is200mAFor power grids with high leakage current, the non rainy season is100mAThe rainy season is300mA.

The second level leakage protector is installed at the outlet of the branch line, and the protected line is relatively short, with low electricity consumption and leakagecurrentSmaller. The rated leakage current of the leakage protector should be between the rated leakage current of the upper and lower level protectors, generally taken as30～75mA.

The third level leakage protector is used to protect single or multiple electrical equipment and is a protective device that directly prevents personal electric shock. Low power consumption and leakage of protected lines and equipmentcurrentSmall, generally not exceeding10mAIt is advisable to choose a rated operating current of30mAThe action time is less than0.1sThe leakage protector.

Beijing Beiguang Jingyi Instrument Equipment Co., Ltd. produces BLD-600V leakage trace tester

• Scope of application

Measure the relative electrical trace resistance of solid electrical insulation materials when exposed to water containing impurities under the action of an electric field at a voltage of up to 600 V.

When a voltage is applied between the specified electrode devices placed on the surface of the material, and the electrolyte drips between the two electrodes at specified time intervals, electrocautery may occur in this experimental situation. The number of liquid droplets necessary to cause material damage increases with the decrease of applied voltage, and no electrical trace occurs below a certain limit.
When the material shows no traces of corrosion even at the highest test voltage, there can be varying degrees of corrosion, and the depth of corrosion can be measured. Some materials can burn during testing.

• Product functional features

The leakage tracing test device is a testing instrument designed and manufactured according to the requirements of standards such as IEC60695, GB4207/IEC60112. Suitable for the determination of residual current trace index and resistance to residual current trace index of solid insulation materials under humid conditions, it has the characteristics of simplicity, accuracy, reliability, and practicality.

• Main technical parameters

1. Electrode material: Test electrode - platinum, electrode rod - copper (platinum purity meets the standard requirement of 99%)
2. Electrode size: (2mm ± 0.1mm) × (5mm ± 0.1mm) × (40mm ± 5mm)
3. Platinum electrode 12mm, inclined at 30 °± 2 °
4. Electrode distance: 4.0mm ± 0.01mm, angle 60 °± 5 °
5. Electrode pressure: 1.00N ± 0.01N
6. Test solution resistance: A solution 0.1% NH4Cl, 3.95 ± 0.05 Ω m; B solution 1.98 ± 0.05 Ω m
7. Dropping device: No adjustment required during testing, easy to operate
8. Droplet height: 35mm ± 5mm (adjustable)
9. Droplet time: 30s ± 0.01s (better than standard) (digital display, adjustable preset)

50Drip time 24.5 minutes ± 2 minutes

1. Droplet count: 1 to 9999 (digital display, pre-set)
2. Test wind speed: 0.2m/s (new standard)
3. Test voltage: 100V~600V (25V division, adjustable)
4. Power voltage drop: 8% at 1.0A ± 0.1A
5. Traceability assessment: 0.50A ± 10%, 2.00s ± 10%
6. The voltage can be adjusted between 100-600V (48-60Hz), and the voltage drop should not exceed 10% when the short-circuit current is 1.0 ± 0.0001A (better than the standard 0.1A);
7. Exhaust hole: Ø 100mm
8. Air environment: Temperature 0~40 ℃ Relative humidity: ≤ 80% Places without obvious vibration and corrosive gases
9. When the short-circuit current is greater than 0 in the test circuit, the relay will operate for 2 seconds to cut off the current and indicate that the test sample is unqualified;
10. Test power supply: 220V 0.6kVA 50-60Hz
11. Dimensions: Width 1160mm, Depth 600mm, Height 1310 (including feet) mm
12. Combustion test area volume:>0.5 cubic meters, length * width * height approximately 900mm × 590mm × 1050mm, background black, background illumination ≤ 20Lux

• Delivery Note

1 Manual copy 1

2 Combustion chamber platform 1

3 Smoke exhaust pipe part 1

4 Certificate of Conformity 1

5 Stainless steel block gauge 1

6 Glass block 1

7 Test needle 1

8 Fuse 1

9 Power cord root 1

• design standards

GB/T4207-2003Method for determining the electrical trace index and resistance to electrical trace index of solid insulation materials under humid conditions

• Applicable standard

IEC60695