爬电距离和电气间隙的确定
Guidance for the measurement of clearances and creepage distances
The rated voltage and overvoltage category are determined (see annex K).
The following information on overvoltage categories is extracted from IEC 60664-1. Overvoltage category is a numeral defining a transient overvoltage condition (瞬态过
电压状态).
Equipment of overvoltage category IV is for use at the origin of the installation 4类设备在源安装地点使用(例如电源
表
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\过流保护设备)
Equipment of overvoltage category III is equipment in fixed installations and for cases where the reliability and the availability of the equipment is subject to special requirements
3类设备是固定设施中的安装的以及有特殊可靠性要求的设备(例如在固定设施中的开
关以及连接到固定设施的工业化设备)
Equipment of overvoltage category II is energy consuming equipment to be supplied from the fixed installation.
2类设备是从固定设施中供电的耗能设备
If such equipment is subjected to special requirements with regard to reliability and availability, overvoltage category III applies
如果此类设备有特殊的可靠性要求的化就按3类处理\
Equipment of overvoltage category I is equipment for connection to circuits in which measures are taken to limit transient overvoltages to an appropriately low level
1类设备是指用于电路连接以及限制瞬态过压低水平的设备(例如保护电路)
电气间隙的确定
The rated impulse voltage is determined from table 15.
Table 15 – Rated impulse voltage
Rated voltage Rated impulse voltage
V V
Overvoltage category
I II III
?50 330 500 800
>50 and ?150 800 1 500 2 500
>150 and ?300 1 500 2 500 4 000
NOTE 1 For multi-phase appliances, the line to neutral or line to earth voltage is used for rated voltage.
NOTE 2 The values are based on the assumption that the appliance will not generate
higher overvoltages than those specified. If higher overvoltages are generated, the clearances have to be increased accordingly.
Table 16 – Minimum clearances
Rated impulse voltage Minimum clearance a
V mm
330 0,5 b, c
500 0,5 b, c
800 0,5 b, c
1 500 0,5 c
2 500 1,5
4 000 3,0
6 000 5,5
8 000 8,0
10 000 11,0
a The distances specified apply only to clearances in air.
b The smaller clearances specified in IEC 60664-1 have not been adopted for practical reasons, such as mass-production tolerances.
c This value is increased to 0,8 mm for pollution degree 3.
爬电距离的确定
The working voltage, pollution degree and material group(如何确定)are determined. The creepage distances of basic insulation and supplementary insulation are measured and compared with the minimum values specified in table 17. A particular creepage distance is then compared with the corresponding clearance of table 16 and
enlarged if necessary in order not to be less than the clearance. For pollution degree 1, the reduced clearance based on the impulse voltage test can be used. However,
the creepage distance can not be less than the values of table 17.
The creepage distances of functional insulation are measured and compared with the minimum values specified in table 18.
The creepage distances of reinforced insulation are measured and compared with twice the minimum values specified in table 17.
Table 17 – Minimum creepage distances for basic insulation
Creepage distance
mm
Pollution degree Working voltage
2 3 V 1 Material group Material group
I II IIIa/IIIb I II IIIa/IIIb
0,2 0,6 0,9 1,2 1,5 1,7 1,9 a ,, 50
>50 and 0,3 0,8 1,1 1,5 1,9 2,1 2,4 ,,125
>125 and 0,6 1,3 1,8 2,5 3,2 3,6 4,0 ,,250
0,4 1,0 1,4 2,0 2,5 2,8 3,2 b >250 and 1,0 2,0 2,8 4,0 5,0 5,6 6,3 ,,400
>400 and 1,3 2,5 3,6 5,0 6,3 7,1 8,0 ,,500
>500 and 1,8 3,2 4,5 6,3 8,0 9,0 10,0 ,,800
>800 and 2,4 4,0 5,6 8,0 10,0 11,0 12,5 ,,1 000
>1 000 and 3,2 5,0 7,1 10,0 12,5 14,0 16,0 ,,1 250
>1 250 and 4,2 6,3 9,0 12,5 16,0 18,0 20,0 ,,1 600
>1 600 and 5,6 8,0 11,0 16,0 20,0 22,0 25,0 ,,2 000
>2 000 and 7,5 10,0 14,0 20,0 25,0 28,0 32,0 ,,2 500
>2 500 and 10,0 12,5 18,0 25,0 32,0 36,0 40,0 ,,3 200
>3 200 and 12,5 16,0 22,0 32,0 40,0 45,0 50,0 ,,4 000
>4 000 and 16,0 20,0 28,0 40,0 50,0 56,0 63,0 ,,5 000
>5 000 and 20,0 25,0 36,0 50,0 63,0 71,0 80,0 ,,6 300
>6 300 and 25,0 32,0 45,0 63,0 80,0 90,0 100,0 ,,8 000
>8 000 and 32,0 40,0 56,0 80,0 100,0 110,0 125,0 ,,10 000
>10 000 and 40,0 50,0 71,0 100,0 125,0 140,0 160,0 ,,12 500
NOTE 1 Lacquered conductors of windings are considered to be bare conductors, but creepage distances need not be greater than the associated clearance specified in table 16 taking into account 29.1.1. NOTE 2 For glass, ceramics and other inorganic insulating materials that do not track, creepage distances need not be greater than the associated clearance.
NOTE 3 Except for circuits on the secondary side of an isolating transformer, the working voltage is considered to be not less than the rated voltage of the appliance.
a Material group IIIb is allowed if the working voltage does not exceed 50 V.
b is for functional insulation