Carrier PIC 5+, Installation, Operation And Maintenance Instructions

Page: 109 / 116

109
temperature by measuring voltage drop; if the controls are powered off, determine sensor temperature by
measuring resistance. Compare the readings to the values listed in Table 22.
10.4 Resistance Check
Turn off the control power from the module, disconnect the terminal plug of the sensor in question. With a digital
ohmmeter, measure sensor resistance between receptacles as designated by the wiring diagram. The resistance
and corresponding temperature are listed in table 22. Check the resistance of both wires to ground .This
resistance should be infinite.
10.5 Voltage Drop Check
The voltage drop across any energized sensor can be measured with a digital voltmeter while the control is
energized.
Table 22 lists the relationship between temperature and sensor voltage drop (dv volts measured
across the energized sensor). Exercise care when measuring voltage to prevent damage to the sensor leads,
connector plugs, and modules. Sensors should also be checked at the sensor plugs.
CAUTION: Relieve all refrigerant pressure or drain the water before removing any thermowell threaded into the
refrigerant pressure boundary. Failure to do so could result in personal injury and equipment damage.
Temperature
(°C)
Pic
voltage
drop (V)
Resistance
(Ohms)
T
(°C)
Pic v.d.
(V)
R
(Ohms)
T
(°C)
Pic
v.d.
(V)
R
(Ohms)
T
(°C)
Pic v.d.
(V)
R
(Ohms)
-33 4.722 105 616 7 3.242 11 510 47 1.227 2 021 87 0.376 502
-32 4.706 99 640 8 3.185 10 963 48 1.192 1 944 88 0.365 487
-31 4.688 93 928 9 3.129 10 444 49 1.158 1 871 89 0.355 472
-30 4.67 88 480 10 3.074 9 949 50 1.124 1 801 90 0.344 458
-29 4.65 83 297 11 3.016 9 486 51 1.091 1 734 91 0.335 444
-28 4.63 78 377 12 2.959 9 046 52 1.06 1 670 92 0.325 431
-27 4.608 73 722 13 2.901 8 628 53 1.029 1 609 93 0.316 418
-26 4.586 69 332 14 2.844 8 232 54 0.999 1 550 94 0.308 405
-25 4.562 65 205 15 2.788 7 855 55 0.969 1 493 95 0.299 393
-24 4.538 61 343 16 2.73 7 499 56 0.941 1 439 96 0.291 382
-23 4.512 57 745 17 2.672 7 160 57 0.913 1 387 97 0.283 371
-22 4.486 54 411 18 2.615 6 839 58 0.887 1 337 98 0.275 360
-21 4.458 51 341 19 2.559 6 535 59 0.861 1 290 99 0.267 349
-20 4.429 48 536 20 2.503 6 246 60 0.835 1 244
100
0.26 339
-19 4.399 45 819 21 2.447 5 972 61 0.811 1 200
101
0.253 330
-18 4.368 43 263 22 2.391 5 711 62 0.787 1 158
102
0.246 320
-17 4.336 40 858 23 2.335 5 463 63 0.764 1 117
103
0.239 311
-16 4.303 38 598 24 2.28 5 226 64 0.741 1 079
104
0.233 302
-15 4.269 36 476 25 2.227 5 000 65 0.719 1 041
105
0.227 294
-14 4.233 34 484 26 2.173 4 787 66 0.698 1 006
106
0.221 286
-13 4.196 32 613 27 2.12 4 583 67 0.677 971
107
0.215 278
-12 4.158 30 858 28 2.067 4 389 68 0.657 938
108
0.21 270
-11 4.119 29 211 29 2.015 4 204 69 0.638 906
109
0.205 262
-10 4.079 27 663 30 1.965 4 028 70 0.619 876
110
0.198 255
-9 4.037 26 208 31 1.914 3 861 71 0.601 846
111
0.193 248
-8 3.994 24 838 32 1.865 3 701 72 0.583 818
112 0.188
242
-7 3.951 23 545 33 1.816 3 549 73 0.566 791
113
0.183 235
-6 3.906 22 323 34 1.768 3 404 74 0.549 765
114
0.178 229
-5 3.861 21 163 35 1.721 3 266 75 0.533 740
115
0.174 223
-4 3.814 20 083 36 1.675 3 134 76 0.518 715
116
0.17 217
-3 3.765 19 062 37 1.629 3 008 77 0.503 692
117
0.165 211
-2 3.716 18 097 38 1.585 2 888 78 0.488 670
118
0.161 205
-1 3.667 17 185 39 1.542 2 773 79 0.474 648
119
0.157 200
0 3.617 16 325 40 1.499 2 663 80 0.46 628
120
0.153 195
1 3.565 15 513 41 1.457 2 559 81 0.447 608
2 3.512 14 747 42 1.417 2 459 82 0.434 588
3 3.459 14 023 43 1.377 2 363 83 0.422 570
4 3.406 13 341 44 1.338 2 272 84 0.41 552
5 3.353 12 696 45 1.3 2 184 85 0.398 535
6 3.298 12 087 46 1.263 2 101 86 0.387 518
Table 22
– Voltage drop and resistance vs temperature