筛选What is Leakage Current?
Leakage current is a small amount of electrical current that flows from the electrical installation to ground, typically through the system's inherent capacitance. This is a normal phenomenon and is present in most electrical systems.
Why Does Leakage Current Occur?
Leakage current occurs due to the capacitance between conductors and ground in an electrical installation. This capacitive path allows alternating current (AC) to flow to ground, even when there is no fault. In large installations, this current can be quite substantial.
Can Leakage Current Cause Problems?
Yes. While some leakage current is normal, excessive leakage current can cause nuisance tripping of Residual Current Devices (RCDs). For example, a 30 mA RCD may trip anywhere between 15 to 30 mA. If the leakage current reaches 18 mA, the RCD might interpret it as a fault and trip unnecessarily.
How Can Nuisance Tripping Due to Leakage Current Be Prevented?
One effective solution is to subdivide large installations into smaller sub-circuits, each protected by its own RCD. This reduces the leakage current seen by each RCD and minimizes the risk of nuisance tripping. Ideally, the standing leakage current on any circuit protected by a 30 mA RCD should not exceed 6 mA.
Does Leakage Current Change Over Time?
Yes. Leakage current can increase over time as electrical equipment and insulation degrade. Additionally, adding more equipment to the installation can raise the overall leakage current, potentially leading to more frequent RCD trips.
What is LCD Technology and How Does It Help?
Leakage Current Detection (LCD) technology is a cost-effective alternative to Insulation Monitoring Devices (IMDs). It helps monitor and manage leakage current levels in real time, allowing for proactive maintenance and reducing the risk of unexpected RCD tripping.