RET670 Transformer protection

Product Description

RET670 provides fast and selective protection, monitoring and control for two- and three-winding transformers, autotransformers, step-up transformers and generatortransformer block units, phase shifting transformers, special railway transformers and shunt reactors. The IED is designed to operate correctly over a wide frequency range in order to accommodate power system frequency variations during disturbances and generator start-up and shut-down.
RET670 has a fast, low-impedance differential protection function with very low requirements on the CTs.It is suitable for differential applications with multi-breaker arrangements with up to six restraint CT inputs. The differential protection function is provided with a 2nd harmonic and waveform-block restraint feature to avoid tripping for CT saturation and transformer inrush current, and 5th harmonic restraint to avoid tripping for transformer overexcitation.
The differential function offers a high sensitivity for low-level internal faults by using a sensitive differential protection feature based on an amplitude measurement and directional comparison of the negative sequence components.
Multiple low impedance restricted earth-fault protection functions are available as a sensitive and fast main protection against winding earth faults. This function includes a internal/ external fault discriminator for additional security.

RET670 1MRK004816-AC