Power injection measurement

The impedance of large electrode systems to ground can be measured by the current injection method. In this measuring method, a test current is injected into the earthing system against a remote electrode. The potential rise that is formed is used to measure the transition resistance of the plant to distant soil. Step and contact voltages are measured directly on the system's earthing system.

A grounding system must ensure the safety of the electrical system. It depends on good internal connections, and good connection to the surrounding soil. Fault in the earthing system can lead to dangerous and undesirable events. Measurement with the current injection method helps to ensure the personal and operational safety of the system.

When the measurements are completed, the contact voltage is calculated in relation to the dimensioned residual current associated with the system. The results of the measurements are analyzed and documented in accordance with current regulatory requirements for earthing systems, set in FEF: 2006 and NEK440: 2015.

Regulatory requirements

In FEF: 2006, FEL and NEK 440: 2015, specific requirements are set for control of the earthing system. Among other things, important and exposed parts of the earthing system must be checked periodically, and at least every ten years.