ACR Systems News
Hardest Working Data Loggers in the Industry - ACR
Troubleshooting Incorrect Readings

SmartReader 2 / SmartReader Plus 2

  1. Make sure that the channels are active and correct equation numbers are selected (Equation 71 for the RH channel and equation 45 for the temperature channel)
  2. Check the real-time temperature readings of the internal temperature sensor on the logger and see whether it changes if you heat it up by blowing on it or putting your finger on it.
  3. Allow the sensors to reach equilibrium before taking readings.
  4. Check the calibration card of the logger and make sure that correct calibration values (Low, Mid, High) are saved on the logger.
  5. Note that the accuracy of the SR2 logger (RH channels) is 4% From 10 to 90% and temperature range of -20C to 40C ( -4F to 104F) and that of the  SRP2 logger is 3% From 10 to 90% and temperature range of -20C to 40C ( -4F to 104F).
  6. If the logger was calibrated more than a year ago, it requires calibration. Contact ACR Systems Inc. to arrange for sending the logger for calibration or proceed with the calibration of the logger as is explained in the Appendix B in the Reference Guide.

SmartReader 3 / SmartReader Plus 3

If the readings are "0" Amps regardless of the current levels, then check the following:

  1. Check to see that the jaws are firmly clamped together forming a solid electrical connection.
  2. Check the electrical connections between the logger and the current transformer (CT).
  3. Check to see that you are not recording a current below 10% of the range.  Amprobes current transformers will record 0 amps below 10% of the range since a diode rectified circuit is used.
  4. Check to ensure that the conductors are split and that the CT's are not clamped around more than one conductor.
  5. Compatibility of the CT with the data logger:  If the serial number is below 12,000 you must use the Amprobe A60/70FL with the rotary range selection switch.  If the serial number is post 12,000, you may use the Amprobe A60/70FL with the slide range selection switch or the rotary range selection switch.  The rotary range selection switch versions can be used with either pre or post 12,000 serial number loggers.

If the readings are not "0" Amps but are incorrect, then check the following:

  1. Check the equation number to see that it matches the current transformer, the range selection switch and the serial number of the logger.  If using any of the Amprobe CT's do not use equations 9, 24, 25, 26, 27, 28 or 29.  These are for the obsolete Fluke probes.
  2. Check to see that the CT you are using is matched to the frequency you are monitoring. The A60FL and the A70FL are for 60Hz, and the A65FL and the A75FL are for 50Hz power.
  3. Check to ensure that the lowest possible current range is being used to obtain the best accuracy and resolution.
  4. Check to see if the scaling factor is set in TrendReader 2 under Preferences, Unit Conversions, AC Current. Check to see that Amps are selected and that the scale for amps is set to 1 and the offset set to 0.
  5. What kind of reference instrument is the ACR equipment being compared to? Amprobe's CT's record average responding RMS current. If you are comparing it to a true RMS meter, there may be harmonics present, which the true RMS meter would record, however the Amprobe CT's will not. Also check the accuracy specifications of the reference meter. Add the accuracy spec of the ACR equipment to the accuracy spec of the reference instrument to determine if the difference in readings is considered normal. Also check to see that the waveform is sinusoidal.

SmartReader 5 / SmartReader Plus 5 / SmartReader Plus 6

  1. Make sure that you are using the correct equation numbers.

    The correct equation numbers for the SRP5 and SRP6 loggers are:

    J type thermocouple Equation 50
    K type thermocouple Equation 52
    T type thermocouple Equation 54
    S type thermocouple Equation 74
    E type thermocouple Equation 90

    Do not use equation numbers 49, 51, 53 and 73 with SRP loggers.

    The correct equation numbers for the SR5 are:

    J type thermocouple Equation 50
    K type thermocouple Equation 52
    T type thermocouple Equation 54
    S type thermocouple Equation 74

    The equation number for the Internal Temperature channel should be 45.

  2. Make sure that the "Low", "Mid", "High" calibration values are correct and are exactly the same as that  printed on the calibration card of the logger.
  3. Always give enough time for the thermocouple and the logger to come to equilibrium temperature. For example: to have correct readings, if you are moving the logger from outdoors to indoors, let it sit for a while until the logger's temperature comes to equilibrium and then start readings. (Note that the internal thermistor is for cold junction compensation and if the logger is carried from outdoors to indoors, you should give the logger enough time to come to equilibrium).
  4. Note: As long as the readings of the logger are within the accuracy specification then there will be no problem. For the accuracy specification of these loggers refer to the related sections.
  5. If you have extended the cable of the thermocouple, make sure that the connection is secure. Any loose connection results in incorrect readings.
  6. Use ungrounded thermocouples to prevent grounding loops.

SmartReader 7 / SmartReader Plus 7

  1. Make sure that correct equation numbers are used.
  2. If you are connecting more than one transducer to the logger, make sure that there is no grounding loop. SRP7 has four common inputs (Labeled "Common"). SR7 has two Common inputs (Labeled "Common"). The Common inputs on the logger are not isolated from each other and can be used as the negative "-" connection for the power supply (or battery) and any of the transducers being logged by these loggers. These common channels are all connected internally. A grounding loop can occur when there is more than one path to ground in your logger-transducer circuit. Ground loops can damage your logger as well as your transducers. To avoid ground-loop problems in your SRP7 circuit:
    • Do not use more than one grounded power supply to excite your transducers
    • Do not connect your logger to your computer for real time readings unless your computer is battery-operated (i.e. not grounded) or your transducer power supply is not grounded.

    If you must use more than one grounded power supply in your logger circuit, each transducer you use must be isolated. If you must use non-isolated transducers, then you must use a Signal Repeater/Loop Isolator between the transducer output and the logger.


Sign up today to be the first to know about new ACR products, events & special offers.