Electrical distribution networks with earth-fault compensation (Petersen coil) have existed for a long time but are becoming increasingly common. Compensated networks provide many operational benefits, such as increased safety for people as well as less and shorter power outages for consumers. The challenge of traditional protection has been the reliability of earth-fault protection, especially during intermittent earth faults in underground cables and transient earth faults, sometimes with no detection in the faulty feeder or even with tripping some of the healthy feeders.
ABB has launched a unique solution for reliable earth-fault protection with only one protection function - the multifrequency admittance protection. This method ensures reliable protection also in compensated and isolated (unearthed) networks, irrespective of the type of earth fault. MFA is intended for continuous, intermittent and transient earth faults, and combines both reliability and sensitivity in one function. The new method is equally suitable for overhead line and cable networks.
MFA is easy to use and requires only a few settings. Identical settings can be conveniently used for all feeder protection relays on outgoing feeders.
MFA being an integrated part of the feeder protection relay makes it a cost-efficient solution. There is no need to invest in additional earth-fault protection relays or systems.
MFA is the result of decades of focus on earth-fault protection, our in-depth knowledge about
earth-fault protection, and the practical experience we have acquired by performing a large number of field tests in various substations, with different types of earth faults. This we have done to verify the outstanding performance of our unique function.
In order to help you get more value from our application solutions, we have gathered the most important material and offer it to you in the following categories.