7SR105 Rho and 7SR17 Rho Applications Guide
©2018 Siemens Protection Devices Chapter 7 Page 28 of 31
4.8 Temperature Inputs (TEMP)
The thermal status of the motor can be detected through Temperature inputs (RTD). Motor working temperatures
will determine the life of the motor insulation, each occurrence of increased temperature reduces the life of the
motor. The ambient temperature, coolant temperature, Oil temperature, winding temperature and bearing
temperature of the equipment to be thermally protected can be measured by temperature inputs (RTD).
RTD’s can be connected to the Temperature inputs of the Relay, which provide actual temperature detected in
motors, generators and even transformers. Normally thermal temperature of motor can be monitored with, two
RTD sensors are used to monitor bearing temperature of the rotary machines and the three RTD sensors are
used to monitor the stator winding temperature and one RTD sensors can be used for ambient temperature
measurement.
The following table shows the temperature values according to the RTD resistance.
Table 4-1 RTD Resistance Vs Temperature
Temperature (ºC)
Pt100 Pt250 Pt1000 Ni100 Ni120 Ni250 Cu10
-50 80.306 200.765 803.062 74.255 86.163 185.637 7.104
-45 82.290 205.725 822.901 76.675 89.450 191.689 7.297
-40 84.270 210.676 842.706 79.131 92.752 197.827 7.490
-35 86.247 215.619 862.477 81.621 96.070 204.053 7.683
-30 88.221 220.554 882.216 84.145 99.406 210.364 7.876
-25 90.192 225.480 901.923 86.704 102.767 216.760 8.069
-20 92.159 230.399 921.598 89.296 106.149 223.241 8.262
-15 94.124 235.310 941.243 91.922 109.560 229.805 8.455
-10 96.085 240.214 960.858 94.581 113.002 236.453 8.648
-5 98.044 245.111 980.444 97.274 116.481 243.185 8.841
0 100.000 250.000 1000.000 100.000 120.000 250.000 9.035
5 101.952 254.881 1019.527 102.759 123.561 256.897 9.228
10 103.902 259.756 1039.025 105.551 127.167 263.878 9.421
15 105.849 264.623 1058.494 108.377 130.819 270.943 9.614
20 107.793 269.483 1077.935 111.236 134.518 278.091 9.807
25 109.734 274.336 1097.346 114.129 138.264 285.323 10.000
30 111.672 279.182 1116.729 117.055 142.059 292.639 10.193
35 113.608 284.020 1136.083 120.016 145.904 300.040 10.386
40 115.540 288.852 1155.408 123.011 149.800 307.527 10.579
45 117.470 293.676 1174.704 126.040 153.747 315.101 10.772
50 119.397 298.492 1193.971 129.105 157.745 322.762 10.965
55 121.320 303.302 1213.209 132.204 161.796 330.511 11.159
60 123.241 308.104 1232.419 135.340 165.900 338.350 11.352
65 125.159 312.899 1251.599 138.512 170.057 346.280 11.545
70 127.075 317.687 1270.751 141.720 174.268 354.301 11.738
75 128.987 322.468 1289.874 144.966 178.532 362.416 11.931
80 130.896 327.242 1308.968 148.250 182.848 370.625 12.124
85 132.803 332.008 1328.033 151.572 187.218 378.931 12.317
To Next Page
Loading...
