Figure 78: High Impedance REF Connection 150Figure 79: REF bias characteristic 151Figure 80: Star winding, resistance earthed 154Figure 81: Percentage of winding protected 154Figure 82: Low Impedance REF Scaling Factor 155Figure 83: Hi-Z REF protection for a grounded star winding 156Figure 84: Hi-Z REF protection for a delta winding 157Figure 85: Hi-Z REF Protection for autotransformer configuration 157Figure 86: High Impedance REF for the LV winding 158Figure 87: Circuit Breaker Fail logic - three phase start 167Figure 88: Circuit Breaker Fail logic - single phase start 168Figure 89: Circuit Breaker Fail Trip and Alarm 168Figure 90: Undercurrent and Zero Crossing Detection Logic for CB Fail 169Figure 91: CB Fail SEF Protection Logic 170Figure 92: CB Fail Non Current Protection Logic 171Figure 93: Circuit Breaker mapping 172Figure 94: CB Fail timing 174Figure 95: Undervoltage - single and three phase tripping mode (single stage) 189Figure 96: Overvoltage - single and three phase tripping mode (single stage) 192Figure 97: Rate of Change of Voltage protection logic 194Figure 98: Residual Overvoltage logic 197Figure 99: Residual voltage for a solidly earthed system 198Figure 100: Residual voltage for an impedance earthed system 199Figure 101: Star connected condenser bushings 200Figure 102: Theoretical earth fault in condenser bushing system 200Figure 103: Condenser bushing system vectors 201Figure 104: Device connection with resistors and shorting contact 202Figure 105: Device connection P14D/P94V 203Figure 106: Negative Sequence Overvoltage logic 204Figure 107: Positive Sequence Undervoltage logic 206Figure 108: Positive Sequence Overvoltage logic 207Figure 109: Moving Average undervoltage logic 208Figure 110: Moving Average overvoltage logic 209Figure 111: Moving Average zero sequence voltage logic 209Figure 112: Moving Average positive sequence voltage logic 209Figure 113: Moving Average negative sequence voltage logic 210Figure 114: Average Voltage Protection blocking 210Figure 115: Voltage vector shift logic 211Figure 116: Vector diagram representing steady state condition 212Figure 117: Single phase line diagram showing generator parameters 212P14D Table of FiguresP14D-TM-EN-8 xxi
