Current-Counter Scheme of F-FTU200——LBS

Current-counter scheme logic is implemented by its own F-FTU200(IED is F-RLY100L）, is generally used on radial lines.The automatic sectionalizer uses the detected current signal as the basis for its logic judgment.

When a line fault occurs (over-current short circuit or ground fault), the upstream auto recloser automatically opens. The sectionalizer counts times based on the presence or absence of the fault current. When the sectionalizer count reaches the initial set value, it automatically opens and locks in the absence of voltage and current. This opening and locking of the sectionalizer isolates the permanently faulted section, while simultaneously restoring power to the non-faulty section when the upstream auto recloser.

As marked in the scheme, the counter setting value of LBS21 is 3 times, LBS22 is 2 times, and LBS23 is 1 time;

When a fault occurs downstream of LBS23, the ACR automatically detects the fault current and initiates tripping. With no voltage or current in the line and the counters at LBS21/22/23 incremented by 1, LBS23 reaches its preset threshold. Under these conditions, LBS23 performs tripping and locking. The fault is isolated

When a fault occurs between LBS22 and LBS23, the ACR automatically detects the fault current and initiates tripping. With no voltage or current in the line, the LBS21/LBS22 counters increment by 1. The ACR then performs reclosing, but the fault persists. This triggers another trip, with the LBS21/LBS22 counters increasing by 2. When the LBS22 counter reaches its preset threshold and the line remains voltage-free and current-free, tripping is executed with locking. Subsequently, the ACR recloses, restoring power supply and isolating the fault.

In overhead lines, load breaker switches are used in conjunction with F-FTU200 controllers to realize fault detection, isolation and restoration (FDIR) of feeders, thus reducing outage time, improving power supply reliability, and helping the intelligent upgrading and transformation development of distribution networks.