impulse voltage
The clearances of four insulation types:
1. Basic insulation 2. Supplementary insulation 3. Reinforced insulation 4. Functional insulation
4
Reinforced insulation
8
Functional insulation
3.2
29.2.1 creepage for basic insulation Lacquered conductors of windings
1.5mm Creepage distance of winding need not be greater than the associated clearance specified in table 16
degree 3 applies
Note: The pollution degree should need refer to part 2.
Pollution degree
classification
Standard
Pollution degree
60335 – 2 – 3
II
60335 – 2 – 9
0.5
2500
1.5
4000
3.0
6000
5.5
8000
8.0
1000
11.0
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, the minimum clearance could be found by rated
I
II
III
<=50
330 500 800
>150 and <=150 800 1500 2500
Using category II
>150 and <=300 1500 2500 4000
220 – 240V
The rated impulse voltage was 2500V
29.1.1 clearances of basic insulation
Creepage distance mm
Pollution degree
1
2
3
ห้องสมุดไป่ตู้Material group
Material group
I
II
III a/b
I
II III a/b
0.2 0.6 0.9 1.2 1.5 1.7 1.9ª
0.3 0.8 1.1 1.5 1.9 2.1 2.4
1.6 1.3 1.8 2.5 3.2 3.6 4.0 1.0 2.0 2.8 4.0 5.0 5.6 6.3
Creepage distance mm Pollution degree
1
2
3
Material group
Material group
I
II
III a/b
I
II III a/b
0.2 0.6 0.8 1.1 1.4 1.6 1.8ª
0.3 0.7 1.0 1.4 1.8 2.0 2.2
0.4 1.0 1.4 2.0 2.5 2.8 3.2 0.8 1.6 2.2 3.2 4.0 4.5 5.0
330
500
800
>50 and <=150
800
1500
2500
>150 and <=300
1500
2500
4000
Minimum clearance (Table 2)
Rated impulse voltage V
Minimum clearance mm
330
0.5
500
0.5
800
0.5
1500
➢Working voltage is between >125 and <=250
The creepage of basic insulation
Working voltage V
<=50 >50 and <= 125 >125 and <=250 >250 and <= 400 >400 and <= 500 >500 and <= 800
29.1.3 clearance of reinforced insulation The reinforced insulation using the next step for rated impulse
voltage.
Between terminal and plastic enclosure
>1mm
Tubular 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
1.3 2.5 3.6 5.0 6.3 7.1 8.0
1.8 3.2 4.5 6.3 8.0 9.0 10.0
Minimum creepage distances for functional insulation
Working voltage V
<=50 >50 and <= 125 >125 and <=250 >250 and <= 400 >400 and <= 500 >500 and <= 800
29.1.4 clearance of functional insulation
Between terminals
The functional insulation is between live parts of different potential
PTC Heating element
Hair straighter
Creepage distance mm
Pollution degree
1
2
3
Material group
Material group
I
II
III a/b
I
II III a/b
0.2 0.6 0.9 1.2 1.5 1.7 1.9ª
0.3 0.8 1.1 1.5 1.9 2.1 2.4
1.6 1.3 1.8 2.5 3.2 3.6 4.0 1.0 2.0 2.8 4.0 5.0 5.6 6.3
1.3 2.5 3.6 5.0 6.3 7.1 8.0
1.8 3.2 4.5 6.3 8.0 9.0 10.0
The creepage of basic insulation
Example 1: Water kettle Rating : 220 – 240V 50Hz 2500 – 3000W
➢Pollution degree 3 (refer to standard 60335 – 2 – 15 )
➢Pollution degree 2 applies unless ➢Precautions have been taken to protect the insulation, in which case pollution 1
applies ➢The insulation is subjected to conductive pollution, in which case pollution
Tracking index tester
Tracking index (CTI) values
Minimum creepage distances for basic insulation
Working voltage V
<=50 >50 and <= 125 >125 and <=250 >250 and <= 400 >400 and <= 500 >500 and <= 800
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)
The clearance of basic insulation
Example 1 : Water kettle
Rating
: 220 – 240V 50Hz 2500 – 3000W
Rated voltage Rated impulse voltage
V
(V)
Overvoltage category
1.0 2.0 2.8 4.0 5.0 5.6 6.3
1.8 3.2 4.5 6.3 8.0 9.0 10.0