The OGYD and DGYD product types are members of the EuroProt+ numerical protection relay, made by Protecta Co. Ltd. The EuroProt+ complex protection in respect of hardware and software is a modular device. The modules are assembled and configured according to the requirements, and then the software determines the functions.
Protecta offers two different types of busbar protection. Essentially, both work on the well-known principle: the sum of the currents flowing into and out of the busbar results zero if there are no internal faults. If the sum is not zero, there is an internal fault and a fast trip command is generated. The scheme in both versions is the low-impedance, biased differential scheme, the application of Kirchhoff`s node law.