ABB SPAD 346 C Stabilized Differential Relay Features

ABB SPAD 346 C Stabilized Differential Relay Features:

Integrated three-phase differential relay, overcurrent relay and earth-fault relay

Stabilized three-phase differential relay providing winding short-circuit and interturn fault protection for two-winding transformers and generator-transformer units and winding shortcircuit protection for generators. 

Earth-fault protection for transformer HV and LV side windings according to the desired principle: the stabilized differential current principle, the high-impedance principle, the calculated or measured residual current principle or the neutral current principle 

Three-stage overcurrent protection for transformers and generators and two-stage back-up protection for earth-fault protection 

The operation characteristic of the differential relay easily adapted for different applications 

Short operate times, even with partially saturated current transformers 

Stabilization prevents unwanted operations at faults outside the protected area and transformer inrush currents Blocking based on the ratio of the second harmonic and the fundamental component of the differential current prevents unwanted operations at transformer inrush currents 

Blocking based on the ratio of the fifth harmonic and the basic frequency component of the differential current prevents operation in harmless situations of transformer overexcitation 

- can be eliminated if the ratio of the fifth harmonic and the basic frequency component increases at high overvoltages 

No interposing transformers are needed for the protection of two-winding transformers - numerical vector group matching on HV and LV side 

Wide CT ratio correction range - accurate correction allowed by digital setting 

Sensitive phase current and phase angle displays facilitate the checking of measurement circuit connection and vector group matching 

Four trip and four signal relay outputs available to the protection design engineer 

Five programmable external control inputs intended for the indication and retransmission of alarm and trip signals of gas relays, oil temperature sensors and other sensors of transformer auxiliary devices 

Adjustable CBFP operate time to improve reliability of operation 

Integrated disturbance recorder capable of recording currents and digital signals - signals to be used for triggering selectable 

High immunity to electrical and electromagnetic interference allows the relay to be used in severe environments 

High availability and system reliability due to continuous supervision of hardware and software