Current Differential Protection Relay Block P543

The following functions are available

1. Measurement of all instantaneous & integrated values
2. Circuit breaker control, status & condition monitoring
3. Trip circuit and coil supervision
4. Programmable hotkeys (2)
5. Control inputs
6. Programmable allocation of digital inputs and outputs
7. Fully customizable menu texts
8. Power-up diagnostics and continuous self-monitoring of relay

This Current Differential Protection Relay Block is easily insert in your schematic diagram and connect as you like way.

Phase compensation to take unto account any phase shift across the transformer, possible unbalance of signals from current transformers either side of windings , and the effects of the variety of earthing and winding arrangements. In P543, software interposing CTs (ICTs) are provided to give the required compensation. Inrush blocking or restrain options to cater for high levels of magnetizing current during inrush conditions. For conditions where it is possible to temporarily load the transformer with a voltage in excess of the nominal voltage, the over fluxing blocking prevents unwanted tripping. The fifth harmonic blocking feature does not require a voltage signal. A fifth harmonic signal is derived from the differential current waveform on each phase and blocking is on a per phase basis. The over fluxing protection should be used in such applications to protect the transformer accordingly.Earth faults occurring on a transformer winding or terminal may be of limited magnitude, either due to the impedance present in the earth path or by the percentage of transformer
winding that is involved in the fault. It is common to apply standby earth fault protection fed from a single CT in the transformer earth connection – this provides time-delayed protection for a transformer winding or terminal fault. In general, particularly as the size of the
transformer increases, it becomes unacceptable to rely on time delayed protection to clear winding or terminal faults as this would lead to an increased amount of damage to the transformer. A common requirement is therefore to provide instantaneous phase and earth fault protection. Applying differential protection across the transformer may fulfill these requirements. However, an earth fault occurring on the LV winding, particularly if it is of a limited level, may not be detected by the differential relay, as it is only measuring the corresponding HV current. Therefore, instantaneous protection that is restricted to operating for transformer earth faults only is applied. This is referred to as restricted earth fault protection (REF). When applying differential protection such as REF, some suitable means must be employed to give the protection stability under external fault conditions, therefore ensuring that relay operation only occurs for faults on the transformer winding / connections.