有关爬电距离和空气间隙的标准规定.ppt

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1、,Clause 29Clearances, Creepage distances and solid insulation爬电距离、电气间隙和绝缘穿通距离 (Table 1),Minimum clearance (Table 2),How to find the minimum clearance,Household appliance are in overvoltage category II Select the rated voltage Using the table 1 to find out the rated impulse voltage According to table

2、 2, the minimum clearance could be found by rated impulse voltage,The clearances of four insulation types: Basic insulation Supplementary insulation Reinforced insulation Functional insulation,The clearance of basic insulation,Example 1: Water kettle Rating : 220 240V 50Hz 2500 3000W,220 240V,Using

3、category II,The rated impulse voltage was 2500V,29.1.1 clearances of basic insulation,The minimum clearances of basic insulation was 1.5mm,Special components for basic insulation,The terminals of tubular sheathed heating elements counted 1mm, if the microenvironment is pollution degree 1.,1mm,Tubula

4、r sheathed heating element,Pollution degree 1,29.1.2 clearance of supplement insulation,The minimum clearance is same as the basic insulation,The distance between enclosure and internal wire,29.1.3 clearance of reinforced insulation,The reinforced insulation using the next step for rated impulse vol

5、tage.,Between terminal and plastic enclosure,29.1.4 clearance of functional insulation,Between terminals,The functional insulation is between live parts of different potential,PTC Heating element,Hair straighter,PTC heater,Hair straighter assembly,Different types of PTC Heating elements,Internal con

6、struction of PTC heating element,The clearance between surfaces of PTC heating elements may be reduced to 1mm,The clearance =1mm,Kapton film,PTC heating plate,Electrode plate,29.2 creepage distances,Step 1 (To find out the pollution degree) Pollution degree 2 applies unless Precautions have been tak

7、en to protect the insulation, in which case pollution 1 applies The insulation is subjected to conductive pollution, in which case pollution degree 3 applies Note: The pollution degree should need refer to part 2.,Pollution degree classification,Tracking index (CTI) values Material group I: 600=CTI

8、Material group II: 400=CTI Material group III a: 175 =CTI 400 Material group III b: 100 =CTI175,Step 2 (To find out the material group),Tracking index tester,Tracking index (CTI) values,Minimum creepage distances for basic insulation,The creepage of basic insulation,Example 1: Water kettle Rating :

9、220 240V 50Hz 2500 3000W,Pollution degree 3 (refer to standard 60335 2 15 ) The microenvironment is pollution degree 3 if the insulation can be polluted by condensation from steam produced during normal use of appliance. Assume the material group is III (the tighten grade) Working voltage is between

10、 125 and =250,The creepage of basic insulation,Minimum creepage distances for functional insulation,Summary of Minimum creepage distances,29.2.1 creepage for basic insulationLacquered conductors of windings,1.5mm,Creepage distance of winding need not be greater than the associated clearance specifie

11、d in table 16,Clause 29.2.2,As per clause 29.2.2, the creepage distance of supplementary insulation shall not less than and 2.5mm. The internal wire of micro-switch was not securely fixed that it was possible to be touched by test finger with 2N force. The creepage distance were measured as 0mm,Inte

12、rnal wire shall be access,Clause 29.2.3,The creepage distances of reinforced insulation shall not less than 8mm. As result, the creepage distance was measured 7.5mm between leads of neon lamp and the lamp cover joint.,Leads of neon lamp,Lens,Enclosure,Leon lamp leads,2mm,3mm,2.5m,The creepage distan

13、ces = 2.5+2+3 = 7.5mm,29.2.4 creepage distances of functional insulation,1.5mm,Clause 29.2.4,PCB Track,A B,B A,B A,29.2.4 creepage distance for function insulation,Creepage distances may be reduced if the appliance complies with clause 19 with the functional insulation short-circuited. For example:

14、Electronic component,Electronic component,The transistor leads limitation of creepage distance,Live Part,Supplementary insulation (1mm),Basic insulation,29.3.1 Material thickness requirement for supplementary insulation (1),Supplementary Insulation,Live Part,Reinforced insulation (2mm),29.3.1 Materi

15、al thickness requirement for reinforced insulation (1),Reinforced Insulation,Live Part,1st layer insulation,2nd layer insulation,Each of the layers should withstands the electric strength test for supplementary insulation,29.3.2 Material requirement for supplementary insulation (2),Basic insulation,

16、29.3.2 Material requirement for reinforced insulation (2),Live Part,1st layer insulation,2nd layer insulation,3rd layer insulation,Any two layers together should withstands the electric strength test for reinforced insulation, 1mm,Case 1,Clearance,Creepage distance,= 1mm,Case 2,Clearance,Creepage distance,1mm,Case 3,Clearance,Creepage distance,Path under consideration includes a V shaped groove with internal angle of less than 80and with a width greater than 1mm,Case 4,Clearance,Creepage distance,Case 5,Clearance,Creepage distance,1mm,1mm,