Combined residual current protections

What is differential current, where does it come from?

The differential current is the difference between the currents flowing through the phase wire to the consumer and through the neutral wire back. The sensing element is a differential transformer installed inside the device.

In normal operation of the network, these currents are equal. When a leakage occurs, a leakage current occurs where the incoming current is greater than the outgoing current by the amount of the leakage. If the network leakage current is equal to or higher than 50% of the set point, the device breaks the protected line.

Types of residual current protection

Residual current protections are available in several types:

• Type AC - For alternating current marked with a "~" symbol.
• Type A - Detects alternating current and pulsating direct current. Denoted by "A" or a symbol with two tildes.
• Type B - Used in industry, for alternating and direct current.

Selection of residual current protection

Several factors are taken into account when selecting residual current protection:

1. Purpose of use: For wet rooms - 10mA; for common contacts – 30mA; for building protection – 100mA or 300mA.
2. Combined or standard protection: Combined devices save panel space, while separate installation allows for easier replacement and diagnostics.
3. Type A or AC: If there are appliances with switching power supplies, type A is more reliable.
4. Electromechanical or electronic: Electronic is more budget-friendly, but electromechanical provides better protection against voltage fluctuations.

Conclusion

Choosing the right residual current protection is important to ensure the safety of the electrical system and protect people. With the right device, tailored to the needs of the installation, reliable protection against current leakage and circuit overload can be guaranteed. Pay attention to all the technical indicators of the device specified by the manufacturer in order to make an informed choice.