Type Ac Differential

What is the difference between an AC and A type differential?

The question of the difference between an type AC differential and a type A differential regularly comes up in installation or renovation projects.

The two technologies have coexisted for a long time and each respond to a very specific logic:

• One adapted to traditional circuits whose loads are perfectly known,
• The other thought is to take into account developments linked to electronic equipment now very present in modern installations.

Understanding this distinction allows you to select the protection best aligned with the nature of the circuit, its uses and its possible evolution. Note that the AC type differential, although still present on the market, is no longer authorized in new, renovated or modified installations according to the RGIE.

Type AC vs type A differential: the difference at a glance

The distinction is mainly based on the nature of the residual currents detected:

• The AC type differential covers situations where the leakage current remains sinusoidal.
• The type A differential takes into account the forms of current generated by many current devices: rectifiers, electronic power supplies, digital controls, etc.

The AC type differential: a technology adapted to the identified loads

The AC type differential corresponds to the technology behind differential devices as they are used today.

This age explains why it is a well-documented device, perfectly mastered and always suitable when the circuit is stable, identifiable and without on-board electronics. In these configurations, its behavior is predictable and consistent with the nature of the currents likely to be detected.

When AC type differential is suitable?

In practice, these conditions are rarely guaranteed in modern installations, which explains why the AC type is not recommended in most scalable configurations.

THE AC type differential remains to this day a perfectly suitable solution when the characteristics of the circuit are known and the supplied load is of a strictly resistive nature. This is a residual case of exploitation for the maintenance in service of installations already in place (without modification or evolving use).

The AC type fits naturally into traditional or poorly scalable configurations, where the behavior of the connected equipment is precisely controlled.

AC Type Differential Limits

Be careful, however, because the AC type differential must be used in a specific context:

• Security: As soon as the slightest doubt remains about the presence of electronics, variators or equipment likely to evolve, the AC type differential should not be used. In these cases, only type A guarantees correct and compliant detection.
• Legal: In existing installations, the RGIE requires that any modified, extended or renovated circuit must now be protected by a type A differential. Type AC is therefore only admissible within the framework of strict maintenance in service, without change of use or planned development.

The type A differential: protection adapted to modern devices

Current installations integrate more and more equipment containing electronic components, rectifiers or digital regulations.

In these cases, type A is more suitable because it supports faults that the type AC differential does not detect.

Type A differential characteristics

Type A provides reliable protection in circuits where the nature of the connected devices is not fully controlled or where development is likely. This is the case in most current installations.

• AC and pulsed DC fault detection
• Compatibility with devices with internal electronics
• Adaptation to loads likely to change over time
• Recommended use in the majority of mixed or multi-use circuits

Limitations of Type A

Without calling into question its broad field of application, type A is not intended to detect certain smoothed DC currents, for which types F or B will be more suitable in specific uses (drives, certain IRVE configurations, controlled three-phase equipment).

What type of differential (A, AC, B, F) for which device?

The nature of the loads connected to a circuit directly influences the choice of the type of differential. Some equipment generates strictly sinusoidal residual currents, while others integrate electronic components likely to produce faults of different shapes.

The following table provides an overview of common uses encountered in professional and residential installations. It does not replace manufacturers' recommendations, but allows you to identify the type of protection generally associated with each piece of equipment:

The equipment presented illustrates the diversity of loads encountered in current installations. Some circuits remain compatible with a type AC differential, others involve the presence of electronics, converters or variators, which justifies the use of a type A or, in certain particular cases, a type B differential or integrated DC detection devices.

The final choice always depends on the actual operation of the device, its internal topology and the indications provided by the manufacturer. When it comes to equipment related to energy conversion — such as charging stations for electric vehicles, photovoltaic inverters or certain drives — it is recommended to precisely check their requirements in order to guarantee complete compatibility with the differential device.

Differentials of all types available in the Teconex catalog

At Teconex, we are not limited to technical support: our catalog also includes a range of Teco brand differential devices, covering current needs:

For each product, a technical sheet is available to verify the complete characteristics of the device and its compatibility with the installation requirements.

Our teams remain at your disposal to help you select the appropriate reference, taking into account the real nature of the circuit, the connected loads and the planned developments. Our approach consists of offering a solution consistent with the constraints of your projects, whether it is an AC or A type differential or a complementary technology.

Need more advice? Check out our other articles:

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