Amprobe 5XP-A User manual

V1.0 V1.0
QUICK GUIDE
Resistance diagnostics
for troubleshooting vibrating wire
sensors and cables

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INTRODUCTION
Where damage to a sensor or cable is suspected this guide illustrates the way in which simple
resistance checks can be taken to identify the possible cause of the problem.
Resistance checks can be made with most types of multi-meter which are readily available in the
market.
RESISTANCE OF THE COILS
STEP 1
Set the range to 200Ω or Ω if using a multi-meter which has automatic ranging.
STEP 2
Connect the VW+ (red) conductor to the red lead on the multi-meter and the
VW- (black) to the black lead on the multi-meter.
The correct readings should be as follows ±10%
Pressure Transducer ~ 160Ω
Strain gauge ~ 180Ω
Co-axial coil ~ 50Ω
IF THE VALUES ARE OUT OF THESE RANGES THEN THERE IS A FAULT IN THE COILS
IF THE VALUES ARE 50% THEN THERE IS A PROBLEM WITH ONE OF THE COILS

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RESISTANCE OF THE THERMISTOR
STEP 1
Set the range to 20kΩ or Ω if using a multi-meter which has automatic ranging.
STEP 2
Connect the T+ (green) conductor to the red lead on the multi-meter and the T- (white) to the black
lead on the multi-meter.
The readings will be dependent on the temperature as below:-
10°C ~ 5.971kΩ (5971Ω)
15°C ~ 4.714kΩ (4714Ω)
20°C ~ 3.478kΩ (3478Ω)
25°C ~ 3.000kΩ (3000Ω)
PLEASE REFER TO THE THERMISTOR LOOK UP TABLE ON PAGE 4
IF THESE VALUES DIFFER THEN THERE IS A PROBLEM WITH THE THERMISTOR OR IT’S
CONDUCTORS

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Ohms Temp Ohms Temp Ohms Temp Ohms Temp Ohms Temp
201.1K -50 16.60K -10 2417 30 525.4 70 153.2 110
187.3K -49 15.72K -92317 31 507.8 71 149.0 111
174.5K -48 14.90K -82221 32 490.9 72 145.0 112
162.7K -47 14.12K -72130 33 474.7 73 141.1 113
151.7K -46 13.39K -62042 34 459.0 74 137.2 114
141.6K -45 12.70K -51959 35 444.0 75 133.6 115
132.2K -44 12.05K -41880 36 429.5 76 130.0 116
123.5K -43 11.44K -31805 37 415.6 77 126.5 117
115.4K -42 10.86K -21733 38 402.2 78 123.2 118
107.9K -41 10.31K -11664 39 389.3 79 119.9 119
101.0K -40 9796 01598 40 376.9 80 116.8 120
94.48K -39 9310 11535 41 364.9 81 113.8 121
88.46K -38 8851 21475 42 353.4 82 110.8 122
82.87K -37 8417 31418 43 342.2 83 107.9 123
77.66K -36 8006 41363 44 331.5 84 105.2 124
72.81K -35 7618 51310 45 321.2 85 102.5 125
68.30K -34 7252 61260 46 311.3 86 99.9 126
64.09K -33 6905 71212 47 301.7 87 97.3 127
60.17K -32 6576 81167 48 292.4 88 94.9 128
56.51K -31 6265 91123 49 283.5 89 92.5 129
53.10K -30 5971 10 1081 50 274.9 90 90.2 130
49.91K -29 5692 11 1040 51 266.6 91 87.9 131
46.94K -28 5427 12 1002 52 258.6 92 85.7 132
44.16K -27 5177 13 965.0 53 250.9 93 83.6 133
41.56K -26 4939 14 929.6 54 243.4 94 81.6 134
39.13K -25 4714 15 895.8 55 236.2 95 79.6 135
36.86K -24 4500 16 863.3 56 229.3 96 77.6 136
34.73K -23 4297 17 832.2 57 222.6 97 75.8 137
32.74K -22 4105 18 802.3 58 216.1 98 73.9 138
30.87K -21 3922 19 773.7 59 209.8 99 72.2 139
29.13K -20 3748 20 746.3 60 203.8 100 70.4 140
27.49K -19 3583 21 719.9 61 197.9 101 68.8 141
25.95K -18 3426 22 694.7 62 192.2 102 67.1 142
24.51K -17 3277 23 670.4 63 186.8 103 65.5 143
23.16K -16 3135 24 647.1 64 181.5 104 64.0 144
21.89K -15 3000 25 624.7 65 176.4 105 62.5 145
20.70K -14 2872 26 603.3 66 171.4 106 61.1 146
19.58K -13 2750 27 582.6 67 166.7 107 59.6 147
18.52K -12 2633 28 562.8 68 162.0 108 58.3 148
17.53K -11 2523 29 543.7 69 157.6 109 56.8 149
THERMISTOR LOOK UP TABLE

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RESISTANCE OF ALL INDIVIDUAL CONDUCTORS
STEP 1
Set the range to 20kΩ or Ω if using a multi-meter which has automatic ranging.
STEP 2
All pairs of conductors should be checked by connecting to the red and black leads on the multi-
meter as follows:-
Red & black
Green & white
A value of O.L (open loop) means that there is a high/infinite resistance and therefore it is
likely that the cable has been cut.
If one of the above pairs is OK then check the individual conductors against the earth.

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