Discrete Command Transceiver for Logical line Protection (PPDK-O)

LZL is easy to execute. At its ends, sets of digital relay protection and automation devices with a function of maximum current directional protection, oriented to operation during short circuit on the line, are installed. Power direction bodies have a memory for eliminating the “dead zone” at close faults, when the voltage can drop to zero. Between these sets, communication is established using transceivers of discrete PPDK commands. With short circuit on the line, short circuit power is directed from the busbars of the power station and the busbars of the substation of the power system to the line. By exchanging information using transceivers, both protections, using the logic developed and implemented in the terminals, give the command to disconnect the line. Thus, the absolute selectivity of LZL is ensured. The duration of the protection, taking into account the operation of the transceivers and the circuit breaker drive, is not more than 150 ms.

When using a telephone line, its length can be up to 5 km (up to 14 km on an individual order), when using an optical line, up to 50 km. PPDK differs from existing analogs in the absence of frequency modulation of signals, due to which it was possible to reduce the dimensions of the device, make the process of transceiver more reliable, and significantly reduce the cost.