Residual voltage

Residual voltage

A residual voltage test is used to detect the presence of residual voltage in an electrical or electronic system that remains in the system after the main source of power is disconnected. This test acts as a safety verification that the machine or electrical system is safe from the effects of residual voltage.

Standards associated with this test

The list of standards available by using our equipments.

IEC 60204

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What is residual voltage

Residual voltages are such voltages that remain even after the power is switched – off. It is mainly due to the components that store electrical charges, such as capacitors, inductors and filter components. According to IEC 60204: SAFETY OF MACHINERY – ELECTRICAL EQUIPMENT OF MACHINES, the residual voltage exceeding 60V must discharge within 5 seconds or within 1 second to less than 60V.

Residual voltages test can be exempted for components that store less charge and are not harmful if being contacted by humans. Typically stored charge of 60mC or less is considered safe and is exempted from the Residual voltage test.

The result of the residual voltage test does not affect the performance or operation of the machine. Instead, as mentioned above, it is a safety test that indicates some disturbance in the electrical system and its associated components.

Residual Voltage Testing procedure

There are two methods of measuring residual voltage – External and Internal Mode.

External mode tests the residual voltage on the plug of the main power supply. In this case, internal components such as filters are not considered.

Internal mode tests the residual voltage on internal components such as capacitors. It indicates the voltage discharge capacity of individual components.

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