Specifically, creepage is the shortest distance between the path of two conductive parts of a medical device and is measures along the surface of insulation. The clearance is similar, but very different. It clearance is the shortest distance between two conductive parts, measured through air. In IEC 60601-1 Third Edition, there are. The minimum distance for creepage and clearance will depend on whether the design requires functional, basic, or reinforced isolation ratings. These are the industry standard terms used to describe levels of voltage isolation performance and minimum safety requirements. Clearance Calculator This program is based on Table 2H of IEC 60950. Select the Insulation, Pollution Degree, Nominal AC Mains, and enter the Working Voltage (peak or dc), then click on the button to get the corresponding Clearance in mm and mils.
- High Voltage Creepage Distance Calculator
- High Voltage Creepage Distance
- Creepage Distance Calculator Estimate
- Creepage Distance Iec
Minimum nominal specific creepage distance(a) (mm/kV)(b) |
16 |
20 |
25 |
31 |
Notes:
- Foractual creepage distances the specified manufacturing tolerances are applicable(IEC 60273, 60305, 60433 and 60720).
- rms valuecorresponding to the highest voltage for equipment (phase to phase).
- In very lightpolluted areas creepage distances less than 16 mm/kV can be used depending uponservice experience. 12 mm/kV seems to be a lower limit.
- Incases of exceptional pollution a specific nominal creepage distance of 31 mm/kVmay not be adequate. Depending upon service experience and/ or laboratory testresults a higher value of specific creepage distance can be used.
electrolytewith moisture from rain or condensation. When the grease becomes saturated withdirt it must be removed and a new coat applied.
Greasingis not recommended for use with anti-fog insulator shed profiles.
Thegrease tends to get trapped in the grooves on the underside of the shed andbridged by conductive dirt forming on the grease surface thereby reducing theoverall insulator creepage distance.
Typicalcreepage values for either cap and pin insulator strings or post insulators at132 kV under very heavy pollution, classification IV, would be determined asfollows:
Nominalvoltage 132kV rms
Maximumrated voltage phase to phase
Testcreepage distance 145kV * 31mm/kV = 4495mm
Typicalsubstation insulator 80 kN minimum failing load
Spacingdistance 127mm
Numberof insulators required to provide 4495 mm creepage using cap and pin porcelainstring insulators =4495/330 = 13.6. Therefore the minimum total number ofinsulators per string would be 14. In this case failure of one unit wouldreduce the creepage distance to 4165 mm, equivalent to an effective value of28.7 mm/kV @ 145kV-rated voltage. However, at the nominal system voltage of 132kV the design value is maintained at 31.5mm/kV. Minimum length of suspensioninsulator string =14 * 127 = 1778mm. Alternatively, 15 insulators per stringcould be specified in order to maintain the recommended creepage distance at145kV-rated voltage under a one insulator shed failure condition. This allowsfull overhead line operation between normal line maintenance outages at theexpense of increased overall string length of 1905mm.
CreepageCreepage refers to the minimum distance between two conductive parts through the surface of the insulation. Creepage is an important characteristic as reduced creepage will result in tracking along the surface of the insulation.
Tracking refers to the flow of current along the surface of the insulation. Tracking causes localised heating and carbonization of the surface. This, eventually, leads to failure of the insulation.
The Comparative Tracking Index (CTI). The comparative tracking index gives the minimum voltage which can cause tracking across the surface of an insulation. Creepage also depends on contamination of the surface, humidity, corrosive chemicals and the altitude in which the equipment is installed.
High Voltage Creepage Distance Calculator
High Voltage Creepage Distance
ClearanceClearance refers to the shortest distance through air between two conductive parts. If the Clearance is less than required, it will result in flashover due to dielectric breakdown in air. Dielectric breakdown is dependent on other factors as well such as humidity, contamination, altitude and temperature.