Voltage Fluctuations

Voltage variations
By connecting electrical and electronic equipment to low-voltage power supply networks, they are subject to voltage variations. Voltage variations are caused by the continuoulsy varying loads connected to the network.

Voltage variations are not always abrupt, because of the reaction time of rotating machines and protection elements connected to the power supply network. If large mains networks are disconnected (local, within a plant or wide aea within a region) the voltage will only decrease gradually due to the many rotating machines, which are connected to the mains networks. For a short period, the rotating machines will operate as generators sending power into the network. Some equipment is more sensitive to gradual variations in voltage than to abrupt change.

However, all electric and electronic equipment should work properly when these variations are within certain limitations (c.q. -15% / + 10%). By applying these voltages to the equipment, the immunity is determined. No malfunction or dangerous situation shall occur.

When performing the tests it is required that the EUT and possible auxiliary equipment are exercising all normal modes of operation. The test results may be classified on the basis of the operating conditions and functional specifications of the EUT, according to the following performance criteria:

• (A) Normal performance within the specification limits;
• (B) Temporary degradation or loss of function or performance which is self-recoverable;
• (C) Temporary degradation or loss of function or performance which requires operator intervention or system reset;
• (D) Temporary degradation or loss of function or performance which is not recoverable, due to damage of equipment (components) or software, or loss of data.