MiCOM P645 Transformer Protection Relays

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 over fluxing protection, plus backup protection for uncleared external faults. Model variants cover two and three-winding transformers (including auto-transformers), with up to five sets of 3-phase CT inputs.

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
• Adaptable to transformers with considerable CT mismatch between terminals – matching factor up to 20
• 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
• No internal batteries in GE-branded models – removes a maintenance item and eases air-freight logistics
• Supports all major digital control system protocols, easing integration into DCS, SCADA and engineering workstations
• NERC CIP cybersecurity
• Binary inputs ESI48-4 EB2 compliant
• Harsh environment protection extends the life of the product

TECHNICAL SPECIFICATION

• Case 60TE/80TE
• Number of CT Inputs 18 (15 Bias, 3EF)
• Number of VT inputs 1 or 4
• Number of bias inputs (3-phase CT sets) 5
• Optically coupled digital inputs 16 - 40
• Standard relay output contacts 8 - 24
• Function keys 10
• Under voltage/Overvoltage/Residual voltage protection-Yes
• Under frequency/Over frequency protection -Yes
• Over fluxing protection 1-phase + 3-phase
• Programmable LEDs 18 tri-colour