IEC 60068-2-27:2008 Mechanical Shock Test — Test Ea
What a brief acceleration pulse can reveal inside a device
A device may look undamaged after a sudden stop while a connector, board support or internal fastening has been affected. IEC 60068-2-27:2008 defines Test Ea for assessing a specimen under specified non-repetitive or repetitive mechanical shocks. It belongs to the IEC 60068 test family and is used with IEC 60068-1.
The purpose is to expose mechanical weaknesses, performance degradation or accumulated damage. Think of the enclosure slowing abruptly while an internal mass tends to keep moving. Checking the outside alone cannot establish that the internal connections and operating functions survived.
A peak acceleration is only part of the specification
A useful requirement identifies peak acceleration, pulse duration, pulse shape, direction and number of shocks. The unit g expresses multiples of gravitational acceleration: 30 g is approximately 294 m/s². It is not a force or impact-energy unit. Equal peaks do not necessarily produce equal responses.
The standard’s classical pulse forms are half-sine, final-peak sawtooth and trapezoidal. Select the pulse in relation to the application and the assessment objective. Measured shock and vibration data can help connect the laboratory requirement to the real environment.
See what changes when the duration changes
Both illustrative pulses peak at 30 g, but last 6 ms and 11 ms. For an ideal half-sine, the velocity change during the pulse is Δv = 2 × apeak × T / π. The examples give approximately 1.12 m/s and 2.06 m/s, respectively. These values illustrate the relationship; they are not a universal product test requirement.
The area under an acceleration–time curve is velocity change, not energy. The longer pulse produces more velocity change here. Which pulse is more damaging to a particular product also depends on its natural frequencies and damping. A shock response spectrum describes how systems with different natural frequencies can respond.
Choose the test that matches the mechanical event
| Test | What is applied |
|---|---|
| Test Ea — Shock | A defined acceleration pulse applied to a specimen attached to the test arrangement. |
| Test Ec — Rough handling | Handling effects such as drops, toppling and related events. |
| Test Eh — Hammer impact | Impacts delivered to a surface with a specified impact energy. |
| Sinusoidal vibration | Vibration at specified frequencies or over a frequency sweep. |
| Random vibration | Random vibration defined by a specified spectrum. |
Shock, drop and hammer tests are not interchangeable. Choosing between sinusoidal and random vibration is another decision. A vibration-test selection guide does not automatically define the shock requirement.
Mounting and monitoring determine what the result means
The report should identify orientation, attachment points, fixture and accessories. A DIN-rail device and the same device held in another arrangement may receive different mechanical loading. The relevant specification determines whether the specimen operates during testing and which functions must be monitored.
A controller might work after the pulse while having experienced a brief connection interruption during it. Plan monitoring to detect the performance changes that matter. A general-purpose vibration meter cannot verify a short shock unless its bandwidth and recording capabilities are suitable. For protection equipment, examine IEC 60255-21-2 shock requirements and the corresponding vibration requirements separately.
Relate severity to the intended environment
IEC 60721 classifies environments; an environmental class and a test method serve different purposes. Consider the relevant environmental parameters, transport and handling conditions or stationary use in a protected location. Correlating an environmental class with a test requires an application-specific justification.