There is a note in table 17 and table 18 as “For working voltages > 10 V and ≤ 630 V, if the voltage is not specified in the table, the values of creepage distances may be found by interpolation.”. If the operating voltage is not the value listed in the table, then we usually need to calculate to get the limit value, for convenience, I prepared an excel table, testers can directly query the table to get the corresponding limit value.
The emphasis here is on a part of the construction on the appliance, which can meet the requirements of double insulation or reinforced insulation. Therefore, a class I appliance will also contain a class II construction .Example: The oven shown in the figure below uses a metal shell and a plastic switch knob. When the…
safety isolating transformer: transformer, the input winding of which is electrically separated from the output winding by an insulation at least equivalent to double insulation or reinforced insulation, that is intended to supply an appliance or circuit at safety extra-low voltage The transformer mentioned here is used to supply power to appliances or circuits. Most…
class III appliance: appliance in which protection against electric shock relies on supply at safety extra-low voltage and in which voltages higher than those of safety extra-low voltage are not generated.NOTE basic insulation may be required in addition to supply at SELV. Refer to 8.1.4. To understand this, you need to first understand what is…
class I appliance: appliance in which protection against electric shock does not rely on basic insulation only but which includes an additional safety precaution, in that conductive accessible parts are connected to the protective earthing conductor in the fixed wiring of the installation in such a way that conductive accessible parts cannot become live in…
functional insulation as well as other insulation exists on circuit boards. Typically, the surface environment of a circuit board is determined to be either Pollution degree 3 or pollution degree 2.If the circuit board is mounted in an electrical box and sealed with a solid sealant, the sealing will look as follows: What should be…
We are discussing here the second structure of the PTC heating element, PTC heating element structure please refer to the explanation of its definition. How is the creepage distance of the functional insulation at the location of the red circle in Figure 1 determined? We all know that NOTE 1 of TABLE 18 section has…
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