Voltage Dips and Interruptions Test: What It Means for Your Product?

Power quality is never perfect. In real electrical environments it is used in factories, hospitals, office buildings, homes. Also, the supply voltage fluctuates constantly. Brief sags during motor startup, momentary interruptions when a fuse blows upstream, short reductions when the grid switches between sources. These events happen thousands of times daily across electrical infrastructure worldwide.

The voltage dips and interruptions test exists to determine whether your electronic product handles these events gracefully or fails in ways that frustrate users and create safety risks.

What the Test Actually Simulates?

A voltage dips and interruptions test applies controlled reductions and complete interruptions to a device's power supply, replicating the real-world events it will encounter during its operating life.

The governing standard is IEC 61000-4-11 for single-phase equipment and IEC 61000-4-34 for equipment with input current exceeding 16A per phase. These define three distinct phenomena:-

Voltage Dips: The sudden reductions in supply voltage lasting from half a cycle to several seconds, typically caused by faults elsewhere in the electrical network

Short Interruptions: Complete loss of supply voltage for up to one minute, occurring when protection devices operate and then restore supply

Voltage Variations: Gradual changes in supply voltage over longer periods

Each is tested at specific reduction depths  typically 0%, 40%, 70%, and 80% of nominal voltage  and specific durations measured in cycles of the supply frequency.

Why Products Fail this Test?

Voltage dips and interruptions test failures reveal design weaknesses that wouldn't surface in normal bench testing:-

* Inadequate bulk capacitance on the power supply that can't sustain operation through brief interruptions

* Microcontroller reset behaviour triggered by power supply ripple during dips, causing unexpected equipment restarts

* Loss of programme state in equipment that doesn't protect volatile memory during supply disturbances

* Relay and contactor drop-out at reduced voltage levels that fall within the dip test range

Compliance Requirements

For CE marking, many product categories require demonstrated immunity to voltage dips and interruptions as part of the EMC Directive requirements. Industrial equipment, medical devices, and information technology equipment all face specific immunity level requirements defined by their respective product standards.

The Practical Design Implication

A voltage dips and interruptions test failure is almost always a power supply design issue. Holdup time , the duration a power supply can maintain output after input is lost is the critical parameter. Designing adequate holdup time from the start is far less expensive than redesigning after a certification failure.