Leakage Current

Leakage Current Detection (LCD) technology is used for detection of dangerous leakage currents in equipment or installations.

The Western Automation LCD technology can detect AC or DC leakage fault currents and can be used in AC or DC installations and in air conditioners and solar panels.

LCD technology can also be used as a cost-effective alternative to Insulation Monitoring Devices (IMD).

Normal or acceptable levels of leakage current can occur due to capacitance on the installation and most installations will have some degree of leakage current. The capacitance and the capacitive path between the electrical installation and ground provide a path for some AC leakage current to flow to ground. This current level may be quite substantial in large installations.

A 30 milliamp RCD will generally trip anywhere from 50% to 100% of its rating. In this instance the RCD will trip between 15 to 30 milliamps. In the event of a leakage current of 18 milliamps there is a high risk that the RCD will nuisance trip due to the leakage current and not due to a fault. It will see this leakage current as though it was a fault current and it may react and trip.

The solution to this problem is to subdivide larger installations into sub-circuits, each of which can be protected by an RCD. This will result in a reduction in the leakage current seen by each RCD and thereby reduce the risk of nuisance tripping. Ideally the standing leakage current on any circuit protected by a 30mA RCD should not exceed 6mA.

Another common problem with leakage current is its tendency to increase over time as an installation or the equipment on the installation ages and deteriorates. Also, additional equipment may be added over time which can add to the overall level of leakage current.