Date Code 20010515
Applications
5-17
SEL-2BFR, -2/BFR Instruction Manual
be restrained for an actual failure. Calculate the negative-sequence voltage present during a close
resistor failure using the equations for V2 above.
62OP Time Delay Pickup Setting
The 62OP time delay pickup timer delays heating of the resistor thermal models for a settable
time following 37OP element assertion. This time delay allows thermal elements to ride through
switching transients produced by capacitively coupled voltage transformers (CCVT).
For the example protected breaker, we select a setting of:
62OP = 3 cycles.
CRTC and TRTC Resistor Cooling Time Constants
The relay continuously models breaker resistor cooling. Define the modeling rate by setting
CRTC and TRTC, the close and trip resistor cooling time constant settings.
The circuit breaker manufacturer should be able to provide data regarding resistor cooling time
constants. If not, you can calculate these constants as follows. Assume that cooling from 200°C
to near ambient temperature takes four hours or three time constants (95 percent cooled). This
implies a cooling time constant of:
minutes
80
3
minutes
240
CRTC
=
=
For the example, 80-minute cooling time constants were selected for CRTC and TRTC.
If you select an inaccurate cooling time constant, the resistor energy models may not be realistic
for some time after breaker operations. For instance, if the cooling time constant is too short, a
breaker resistor may actually contain more energy than is modeled, making the pending failure
and failure energy levels less conservative than intended.
Select Breaker Pole Flashover Settings
See
Logic Description
in
Section 2: Specifications
for a description of breaker pole flashover
protection logic operation.
If possible, set the 59FO element just lower than the voltage measured across the breaker when
resistors are left in service. This setting makes the flashover logic more secure during close
operations.
For the example breaker, V
MIN
, was calculated:
V
MIN
= 4.33 V secondary
The accuracy specification of the 59FO element is ±0.09 V secondary ±5% of settings, so:
59FO maximum error
= 0.09 V + (0.05) • 4.33 V
= 0.31 V secondary
Summary of Contents for SEL-2BFR
Page 3: ......
Page 4: ......
Page 6: ... ...
Page 8: ... ...
Page 10: ......
Page 16: ... ...
Page 20: ......
Page 59: ......
Page 60: ......
Page 61: ......
Page 62: ......
Page 63: ......
Page 64: ......
Page 65: ......
Page 66: ......
Page 67: ......
Page 68: ......
Page 69: ......
Page 70: ......
Page 71: ......
Page 72: ......
Page 73: ......
Page 74: ......
Page 75: ......
Page 76: ......
Page 77: ......
Page 78: ......
Page 79: ......
Page 80: ......
Page 81: ......
Page 82: ......
Page 83: ......
Page 84: ......
Page 85: ......
Page 86: ......
Page 87: ......
Page 88: ......
Page 89: ......
Page 90: ......
Page 91: ......
Page 92: ......
Page 93: ......
Page 94: ......
Page 95: ......
Page 96: ......
Page 97: ......
Page 98: ......
Page 99: ......
Page 100: ......
Page 101: ......
Page 102: ......
Page 103: ......
Page 104: ......
Page 105: ......
Page 106: ......
Page 107: ......
Page 108: ......
Page 109: ......
Page 110: ......
Page 111: ......
Page 112: ......
Page 113: ......
Page 114: ......
Page 144: ... ...
Page 150: ... ...
Page 151: ......
Page 152: ......
Page 153: ......
Page 154: ......
Page 155: ......
Page 156: ......
Page 157: ......
Page 158: ......
Page 159: ......
Page 160: ......
Page 161: ......
Page 162: ......
Page 163: ......
Page 164: ......
Page 165: ......
Page 166: ......
Page 167: ......
Page 168: ......
Page 169: ......
Page 170: ......
Page 171: ......
Page 172: ......
Page 173: ......
Page 174: ......
Page 175: ......
Page 176: ......
Page 177: ......
Page 178: ......
Page 179: ......
Page 180: ......
Page 181: ......
Page 182: ......
Page 183: ......
Page 184: ......
Page 185: ......
Page 186: ......
Page 187: ......
Page 188: ......
Page 189: ......
Page 190: ......
Page 191: ......
Page 192: ......
Page 193: ......
Page 194: ......
Page 195: ......
Page 196: ......
Page 197: ......
Page 198: ......
Page 199: ......
Page 200: ......
Page 201: ......
Page 202: ......
Page 203: ......
Page 204: ......
Page 205: ......
Page 206: ......
Page 207: ......
Page 208: ......
Page 209: ......
Page 210: ......
Page 211: ......
Page 212: ......
Page 213: ......
Page 214: ......
Page 215: ......
Page 216: ......
Page 217: ......
Page 218: ......
Page 219: ......
Page 220: ......
Page 222: ......
Page 237: ......
Page 238: ......
Page 239: ......
Page 240: ......