Clause 3 – How to understand the definition of “rated impulse voltage”

Byforest

rated impulse voltage: voltage derived from the rated voltage and the overvoltage category of the appliance, characterizing the specified withstand capability of its insulation against transient overvoltages.

For beginners, it is not really necessary to understand the physical meaning of this definition. The main use of this voltage value in the standard is to determine the limit value of the clearance; referring to Table 15, the rated impulse voltage value can be determined directly.
The top sentence of Table 15 indicates that “Appliances are in overvoltage category II.”. If the rated voltage of the product is AC220-240V, corresponding to the last row of values in the first column of Table 15, the rated pulse voltage is determined to be 2500V.

I have to say that the overvoltage category(OVC) is come from standard IEC 60664-1. below table give us a definition.

On the other hand, there is a drawing to explain overvoltage category(OVC).

Similar Posts

Clause 3 – How to understand the definition of “type X attachment”

Byforest

type X attachment: method of attachment of the supply cord such that it can easily be replacedNote 1 to entry: The supply cord may be specially prepared and only available from the manufacturer or its service agent. A specially prepared cord may include a part of the appliance. First, this definition is for the supply…

Clause 3 – How to understand the definition of “safety extra-low voltage”

Byforest

safety extra-low voltage: voltage not exceeding 42 V between conductors and between conductors and earth, the no-load voltage not exceeding 50 V When safety extra-low voltage is obtained from the supply mains, it is to be through a safety isolating transformer or a convertor with separate windings, the insulation of which complies with double insulation…

Clause 3 – How to understand the definition of “safety isolating transformer”

Byforest

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…

Clause 3 – How to understand the definition of “supplementary insulation”

Byforest

supplementary insulation: independent insulation applied in addition to basic insulation, in order to provide protection against electric shock in the event of a failure of basic insulation An insulation that is outside the basic insulation and is independent of the basic insulation, and is usually accessible to the user. Supplementary insulation, as the name implies,…

|

Clause 3 – How to understand the definition of “PTC heating element”

Byforest

PTC heating element: element intended for heating consisting mainly of positive temperature coefficient resistors that are thermally sensitive and have a rapid non-linear increase in resistance when the temperature is raised through a particular range. As the temperature increases, the resistance of the heating element of the PTC heating element increases. The relationship between temperature…

Clause 3 – How to understand the definition of “type Z attachment”

Byforest

type Z attachment: method of attachment of the supply cord such that any replacement is intended to be made by the manufacturer, its service agent or similar qualified person. The supply cord of some products is molded together with the product and cannot be removed by common tools. Or the power cord of some appliances…