Clause 3 – How to understand the definition of “protective impedance”

protective impedance: impedance connected between live parts and accessible conductive parts of class II constructions so that the current, in normal use and under likely fault conditions in the appliance, is limited to a safe value. Case 1:The first case is usually some situations that require low-voltage power supply, such as adapter-powered products. The output…

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

functional insulation: insulation between conductive parts of different potential which is necessary only for the proper functioning of the appliance. Functional insulation is set because of the functional needs of the appliance. In electrical products, there must be conductive parts with different potentials (different voltages). If the voltage of all energized conductors in the product…

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

reinforced insulation: single insulation applied to live parts, that provides a degree of protection against electric shock equivalent to double insulation under the conditions specified in this standard.NOTE It is not implied that the insulation is one homogeneous piece. The insulation may comprise several layers which cannot be tested singly as supplementary insulation or basic…

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

double insulation: insulation system comprising both basic insulation and supplementary insulation The definition is only to simplify the description of basic insulation and supplementary insulation in the standard, using one name to descirbe two names. As shown in the figure below, the supply cord has two layers of insulation, the inner wire sheath and the…

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

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 “basic insulation”

basic insulation: insulation applied to live parts to provide basic protection against electric shock Generally speaking, a layer of insulation that is in direct contact with a live part can be a common insulating material (such as plastic materials such as PVC and ABS), or it can be air or a distance ( creepage distance) formed…

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

The type of connection is defined by the manufacturer of the appliance. Generally speaking, it is rare to define it as Type X, because this will bring unnecessary risks to the manufacturer. It is commonly defined as Type Y. Of course, if the power cord is cast, it is generally defined as Type Z. The…

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

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…

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

type Y 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. Type Y attachment is generally used for supply cords that are difficult to replace, or when dangerous parts may be touched during replacement. Therefore, it is…