Leakage Current Refers To The Current Formed Through The Surrounding Medium Or Insulating Surface Between Metal Parts That Are Insulated From Each Other, Or Between Live Parts And Grounded Parts, When There Is No Defect In The Application Of Voltage. In The U.S. UL Standard, Leakage Current Is The Current That Can Be Conducted From The Accessible Part Of Household Appliances Including Capacitive Coupling Current. Leakage Current Consists Of Two Parts, One Is The Conduction Current I1 Through The Insulation Resistance; The Other Is The Displacement Through The Distributed Capacitance The Current I2, The Capacitive Reactance Of The Latter Is XC=1/2pfc Is Inversely Proportional To The Power Frequency, And The Distributed Capacitance Current Increases With The Increase Of The Frequency, So The Leakage Current Increases With The Increase Of The Power Frequency. For Example: Using A Thyristor To Supply Power, Its Harmonic The Weight Of The Wave Increases The Leakage Current.
If The Program-Controlled Leakage Current Tester Checks The Insulation Function Of A Circuit Or A System, This Current Includes Everything That Passes Through The Insulating Material.
In Addition To The Current Flowing Into The Earth (Or The Conductive Part Outside The Circuit), It Should Also Include The Current Flowing Into The Earth Through The Capacitive Devices In The Circuit Or System (Distributed Capacitance Can Be Regarded As Capacitive Devices). Longer Wiring Will Constitute A Larger Distribute The Capacity And Increase The Leakage Current.This Should Be Particularly Careful In An Ungrounded System.
The Principle Of Measuring Leakage Current Is Basically The Same As Measuring Insulation Resistance. Measuring Insulation Resistance Is Actually A Kind Of Leakage Current, But It Is Expressed In The Form Of Resistance. However, The Normal Measurement Of Leakage Current Applies Communication Voltage, So Leakage Current Is Measured.
The Current Component Contains A Capacitive Weight Current.
During The Withstand Voltage Inspection, In Order To Maintain The Experimental Equipment And Check The Technical Indicators According To The Rules, It Is Also Necessary To Admit That A High Electric Field Strength That Does Not Damage The Equipment Under Test (Insulation Material) Is Allowed To Flow Through The Equipment Under Test (Insulation Material)* Large Current Value, This Current Is Generally Called Leakage Current, But This Method Is Only Used In The Above Specific Occasions. Please Be Aware Of The Difference.
The Program-Controlled Leakage Current Tester Is Actually The Electrical Circuit Or Equipment That Flows Through The Insulation Part Without Defects And Applied Voltage.
Current. Therefore, It Is One Of The Important Indicators To Measure The Insulation Of Electrical Appliances, And It Is The Primary Indicator Of Product Safety Function.
Keep The Leakage Current At A Small Value, Which Plays An Important Role In The Safety Function Of Forward Products.
The Programmable Leakage Current Tester Is Used To Measure The Leakage Current Irrelevant To The Operation Generated By The Operation Power Supply (Or Other Power Supply) Of The Electrical Appliance Through The Insulation Or Distributed Parameter Impedance, And Its Input Impedance Simulates The Impedance Of The Human Body.
Leakage Current Checker Is Mainly Composed Of Impedance Conversion, Range Conversion, AC-DC Conversion, Expansion, Indicating Equipment, Etc. Some Also Have Over-Current Maintenance, Sound And Light Alarm Circuits And Experimental Voltage Scheduling Equipment, And Their Indicating Equipment Is Divided Into Analog And Digital Two Kinds.
The So-Called Touch Current, In Short, Refers To The Current That Flows Through The Metal Touchable Part Of The Device Through The Human Body To The Grounding Part Or Touchable Part. For This, We Must Use It When Checking The Human Body Simulation Circuit, Parallel Voltmeter, And The Human Body Simulation Circuit Have Different Human Body Simulation Circuits According To Different Product Safety Regulations.
There Are Four Types Of Leakage Current: Semiconductor Component Leakage Current, Power Supply Leakage Current, Capacitor Leakage Current And Filter Leakage Current.
Chinese Name: Leakage Current; Foreign Name: Leakage Current
1 Leakage Current Of Semiconductor Components
2 Power Leakage Current
3 Capacitor Leakage Current
4 Filter Leakage Current
1. Leakage Current Of Semiconductor Components
A Very Small Current Flows Through The PN Junction When It Is Off. When D-S Is Set In Forward Bias And G-S Is Reverse Biased, After The Conductive Channel Is Opened, Current Will Flow From D To S. But In Fact, Because Of The Existence Of Free Electrons, Free Electrons Are Attached To SIO2 And N+, Causing D-S To Leak Current.
2. Power Leakage Current
In Order To Reduce The Disturbance In The Switching Power Supply, According To The National Standard, An EMI Filter Circuit Must Be Installed. Because Of The Connection Of The EMI Circuit, There Is A Slight Current To The Ground After The Switching Power Supply Is Connected To The Power Supply, Which Is The Leakage Current. If It Is Not Grounded, The Computer Shell Will Have A Voltage Of 110 Volts To The Ground, And It Will Feel Numb When Touched By Hand, Which Will Also Affect The Computer Operation.
3. Capacitor Leakage Current
The Capacitor Medium Cannot Be Excellent In Non-Conductivity. When The Capacitor Is Applied With A DC Voltage, The Capacitor Will Have Leakage Current. If The Leakage Current Is Too Large, The Capacitor Will Be Damaged By Heat. In Addition To Electrolytic Capacitors, The Leakage Current Of Other Capacitors Is Very Small, So The Insulation Resistance Parameter Is Used To Indicate Its Insulation Function; And The Electrolytic Capacitor Has A Large Leakage Current, So The Leakage Current Is Used To Indicate Its Insulation Function (Proportional To The Capacity).
Applying An Additional DC Operating Voltage To The Capacitor Will Observe That The Charging Current Changes Greatly, And Then Decreases With Time. When It Reaches A Certain Final Value, The Final Value Of Current That Reaches A More Stable Condition Is Called Leakage Current.
Fourth, Filter Leakage Current
The Definition Of The Leakage Current Of The Power Supply Filter Is: The Current From The Filter Case To The Arbitrary End Of The Communication Incoming Line Under The Additional Communication Voltage.
If All Ports Of The Filter Are Completely Insulated From The Housing, The Value Of The Leakage Current Depends Primarily On The Leakage Current Of The Common-Mode Capacitor CY, That Is, Primarily Depends On The Capacity Of The CY.
Because The Filter Leakage Current Is Related To Personal Safety, All Countries In The World Have Strict Regulations On It: For 220V/50Hz Communication Grid Power Supply, The Leakage Current Of The Noise Filter Is Generally Required To Be Less Than 1mA.
Post time: Feb-06-2021
