PROTECTION

Phase and Neutral Instantaneous Overcurrent

elements with settable time delay: 50TP, 50TN

Phase, Neutral, and Negative Sequence Time

Overcurrent elements: 46. 51P, 51N, 151N

Phase overcurrent element (51P) includes capabil

ity of voltage restraint or voltage control.

Internally calculated phase residual, 3I0. available

on all relays. Optional independent ground input

available. Neutral overcurrent elements (50TN, 51N,

151N) monitor either ground or calculated residual.

Negative sequence overcurrent element (46)

includes algorithm for timing based on generator

K factors or may use standard TOC curves.

All U.S. and IEC timing curves plus user program

mable curve.

Phase Undervoltage and Overvoltage elements:

27P, 127P, 59P, 159P. Elements use a 1 of 3. 2 of

3. or 3 of 3 logic, and monitor either line-line or line

ground voltages.

Auxiliary Undervoltage and Overvoltage elements:

27X, 127X, 59X, 159X. Elements monitor either

fundamental or third harmonic on the optional

auxiliary 4thVT input, or fundamental phase

residual, 3V0. of the phase inputs.

Negative Sequence Overvoltage element: 47

Overexcitation, Volts per Hertz element: 24

Four Under/Overfrequency elements: 81. 181. 281. 381

Forward/Reverse Power: 32. 132

Loss of Excitation (offset sloped VAR flow algo rithm): 40Q, 140Q

Breaker Failure protection function: BF

4 general purpose logic timers: 62. 162. 262. 362

Inadvertent energization protection using 50

elements supervised by 81 and/or 27 elements

100% stator ground fault protection using auxiliary

voltage elements for ground overvoltage and 3rd

harmonic ground undervoltage

Sync check and/or dead bus close supervision

25. 27X (Requires optional 4th VT sensing circuit)

Programmable Logic using BESTlogic

Two protection settings group controllable via relay

logic, 43 Aux switches, and hardwired inputs.

Setting group selection may control tripping logic.

Fuse loss detection (60FL) protects against false

trip due to loss of voltage sensing.