Transformer Protection Systems

​

GE's MiCOM Agile platform of transformer protection relays helps preserve transformer service life and provides fast protection for transformer faults. The platform consists of three model variants (P642, P643 and P645) that cover two and three-winding transformers (including auto-transformers), with up to five sets of 3-phase CT inputs, and offers high and low impedance restricted earth fault, and has integral asset management capability.

​

Key Features

​

• High stability during external fault with heavy CT saturation due to transient bias technique

• No slow-down of differential elements due to 2nd harmonic component in fault currents

• Current transformer supervision operates with or without voltage inputs, fast enough to prevent any spurious tripping and alarm 

• 10 integrated function keys, tri-color LEDs, and graphical programmable logic permit the creation of comprehensive, tailored schemes

​

Overview

​

Transformers are high capital assets in electrical power systems. Elimination of all electrical and mechanical stresses, although desirable to preserve transformer life, is impractical. Adaptive techniques to measure, alarm (or trip) and advise on cumulative service can help to schedule preventive maintenance before a costly failure occurs. Internal faults are a risk for all transformers, with short-circuits dissipating the highest localized energy. Unless cleared quickly, the possibility to rewind windings reduces and core damage may become irreparable.

​

GE's P642, P643 and P645 address all these issues, preserving service life and offering fast protection for transformer faults. A transient bias technique has been included, enhancing relay stability and CT requirements. Hosted on an advanced IED platform, the P64x incorporates differential, REF, thermal, and overfluxing protection, plus backup protection for unclear external faults. Model variants cover two and three-winding transformers (including auto-transformers), with up to five sets of 3-phase CT inputs.

​

Key benefits:

​

• Backup and logging of through faults 

• Simple settings – wizard requires only nameplate data 

• Integrated backup overcurrent per winding or CT input - optional directionalizing when relay fitted with a 3-phase VT  

• Ordering the 3-phase VT permits full monitoring and measurement of power and energy quantities 

​

Main characteristics:

​

• Current loop analogue inputs [CLIO] and analogue outputs [RTD] for remote monitoring 

• Optional single or dual redundant Ethernet available for IEC 61850 or DNP3

• Transient biasing reduces CT knee point dimensioning by typically 25% compared to historical applications

​

P64x IED Software 06

​

The Agile Transformer Management P64x IEDs are now available with software 06A. This software allows new enhancements and protection improvements in the P642, P643 and P645 range of products.

​

The IEDs available with the new software are:

​

• P642 Transformer Management Hardware P / Software v06A

• P643 Transformer Management Hardware M / Software v06A

• P645 Transformer Management Hardware M / Software v06A

​

The 06A software features:

​

• Increased maximum number of digital inputs from 24 to 40 in P643/5 models

• 2nd harmonic current blocking during transformer energization is now available for overcurrent, earth fault and REF protection

• New reference vector group setting allows better compatibility with KBCH phase correction

• Increased setting ranges (0.5 -40 PU) for differential protection high set elements, Is-HS1 and Is-HS2

• Fast operating times of the biased differential element (<33 ms) at low pickups, as low as 20% above the operating characteristic Improved CT requirement