CHAPTER 4: SETPOINTS MONITORING
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–325
NOTE:
RTD type copper (Cu) is only available when order code option ‘S’ is chosen for Slot B or C.
RTD Protection
The 889 relay can monitor up to 13 RTDs, each of which can be configured to have a trip
temperature and an alarm temperature. The RTD protection setpoints can be seen only if
an LVIO card or one or two RTD modules are installed and validated.
The alarm temperature is normally set slightly above the normal running generator
temperature.
The trip temperature is normally set at the insulation rating. Trip Voting has been added for
extra security in the event of RTD malfunction. If enabled, a second RTD must also exceed
the trip temperature of the RTD being checked before a trip will be issued. If the RTD is
chosen to vote with itself, the voting feature is disabled. Each RTD may also be configured
as being of application type None, Stator, Bearing, Ambient or Other. RTDs configured as
Stator type are also used by the thermal model for determining the RTD Bias.
This element also monitors the RTD broken connection and blocks the RTD trip and alarm
functions if the RTD connection is detected as Open or Shorted and generates RTD Open
and RTD Shorted FlexLogic operands. An RTD is detected as Open when the RTD
connection is either open or the temperature is greater than 250°C. An RTD is detected as
Shorted when the RTD connection is either shorted or the temperature is equal to less than
-40°C.
–10 14 96.09 113.00 94.17 8.65
0 32 100.00 120.00 100.00 9.04
10 50 103.90 127.17 105.97 9.42
20 68 107.79 134.52 112.10 9.81
30 86 111.67 142.06 118.38 10.19
40 104 115.54 149.79 124.82 10.58
50 122 119.40 157.74 131.45 10.97
60 140 123.24 165.90 138.25 11.35
70 158 127.08 174.25 145.20 11.74
80 176 130.90 182.84 152.37 12.12
90 194 134.71 191.64 159.70 12.51
100 212 138.51 200.64 167.20 12.90
110 230 142.29 209.85 174.87 13.28
120 248 146.07 219.29 182.75 13.67
130 266 149.83 228.96 190.80 14.06
140 284 153.58 238.85 199.04 14.44
150 302 157.33 248.95 207.45 14.83
160 320 161.05 259.30 216.08 15.22
170 338 164.77 269.91 224.92 15.61
180 356 168.48 280.77 233.97 16.00
190 374 172.17 291.96 243.30 16.39
200 392 175.86 303.46 252.88 16.78
210 410 179.53 315.31 262.76 17.17
220 428 183.19 327.54 272.94 17.56
230 446 186.84 340.14 283.45 17.95
240 464 190.47 353.14 294.28 18.34
250 482 194.10 366.53 305.44 18.73
TEMPERATURE RESISTANCE (IN OHMS)
°C °F 100 Ω PT
(IEC 60751)
120 Ω NI 100 Ω NI 10 Ω CU
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