fire prevention solution on ac power port
TRANSCRIPT
Fire-prevention solution on AC port circuit protectionPatent Protection
A0
1. Background
3. Test Process
2. Test comparison and analysis of multiple solutions
4. Circuit cut off time and current for BCD test
Menu
5. Recommended solution of BCD product
1. Background---Risks Originated from Conventional Application 1. The rated current of fuse which in series in the circuit of power, should be
higher than normal working current and withstand surge current. Assuming SPD paralleled in post circuit becomes disabled in short-circuit condition, fuse in primary circuit, it is possible not open and result in circuit catching fire.
2. Ground potential will rise up when extremely high voltage or lightning hit the ground. Because of the ground impedance(main) or uncertain factors(minor), current may reversely strike power network. In this situation, GDT in power port generates high temperature up to 1000℃ when breakdown last a while( 20A / 5S), and MOV catches fire finally.
Earthing Resistance
2.Test Comparison and Analysis of Multiple Solutions FUSE+MOV+GDT
failOK OK
MOV+T-GDT T-MOV MOV
+BCD
fail
Circuit Diagram
Circuit Open Time@20A
Stability
Process Reliabilit
y
ITEM
3.Test Process –Conventional Solutions
Test Environment:1000V 20A
Earthing Resistance
MOV2 MOV3
MOV1FUSE 15A
FUSE 15A
Fuse(15A) + MOV + GDT
Earthing Resistance
MOV2 MOV3
MOV1
T-GDT
MOV + T-GDT
Test Environment:1000V 20A
3. Test Process- Alternative Solution of Others
Earthing Resistance
T-MOV1 T-MOV2
T-MOV3
T-MOV can not break the circuit @1000V 20A condition, also it generates the voltaic arc during the fire.
T - MOV
Test Environment:1000V 20A
Earthing Resistance
MOV2 MOV3
MOV1
MOV + BCD
MOV+ Heat Shrinkable Tube +BCD
BCD
Bencent newly-developed part BCD could cut off the circuit rapidly and block the current . Test shows not a single firelight could be identified under the harsh condition of 40A thanks to wrapping heat shrinkable tube on BCD.
Test Environment:1000V 20A
3. Test Process- Alternative Solution of Bencent
Test Environment:1000V 40A
4.Circuit cut off time and current for BCD test
MOV
Adjustable Resistance
AC1200V
BCD
Circuit Cut-off Time(s)
Current(A)
5. Recommended Solution of BCD product
Above is circuit diagram for AC power which is common to see in telecommunication and industrial application. Fuse 1 for L and Fuse 2 for N, Fuse 3 for Safety fuse . If F1 and F2 has to pass impulse current 5KA@8/20us, then the I2t of fuse has to be more than 1000 A2s resulting in 15A static current flowing through fuse.
Above are the recommended circuit diagrams with BCD, left for differential mode(DM)protection, right for common mode(CM) integrated protection . Both solutions can save fuses (F1 for L, F2 for N). GDT can keep open both in CM and DM even when MOV fails. BCD can withstand the lightning level more than 10KA and disengaging at power current @1A.
This solution features 1.to provide simplified solution and save space in PCB layout,2. to provide fast responsiveness to cut off circuit to prevent fire.
Thank you!Shenzhen Bencent Electronics Co.,Ltd.ADD: 5/F, Building 1, Hainengda Industrial Park, Baolong 4th road, Longgang , Shenzhen, China 518116
Email : [email protected] [email protected]
TEL: 0086 755 2651 5078
The End.