ACR Electronics SmartReader Plus Manual do Utilizador descarregar pdf (Página 93)

SmartReader Data Logger

surface, penetration, pipe well, or immersion sensing applications, you can usually get

off-the-shelf or even custom probes to suit. Contact your dealer for recommendations.

Writing Your Own Thermistor Equations

Each thermistor temperature probe you use with SmartReader data loggers must be

associated with a standard or custom equation in the TrendReader software. This equation

translates the internal digital logger readings for the specific thermistor, or thermistor type, into

the units of your choice (e.g., degrees Celsius or Fahrenheit).

TrendReader software includes a function that can automatically create custom equations for

use with your own thermistors. See Equations in the TrendReader guide.

1.15.8 Where to Get Thermistors

Thermistor temperature sensors and probe assemblies are available from several different

sources in a wide variety of configurations. You can obtain thermistors just by themselves and

assemble them into your own probes, or order them completely pre-assembled. Some

manufacturers will have off-the-shelf availability of products (or be able to guide you to one of

their distributors who does) or else provide you with a custom probe configuration to suit your

specific need.

1.15.9 How to Choose Thermistors

Obtaining thermistors can be confusing. To help, here are a variety of terms and how they

relate to using them with your SmartReader data loggers.

Interchangeable

Interchangeable is a term that refers to sensors that can be freely used with the same

linearizing equation (the type of equation that TrendReader software uses to convert

resistance readings into temperature) and still produce accurate readings within a certain

degree of accuracy (tolerance). For example, five thermistors with an interchangeability

tolerance of ±0.2°C should be able to produce readings within ±0.2°C. Most interchangeable

thermistors are available in tolerances ranging from ±1.0 down to ±0.05°C within a defined

temperature range (for example, 0 to 70°C). This interchangeability can usually be extended

well beyond this range, however, the tolerance degrades.

Interchangeable thermistors are strongly recommended if the sensors are intended for use on

more than one SmartReader channel or data logger. When acquiring interchangeable

thermistors,make sure to request the specific resistance-temperature data that you will need

for calibration purposes.

Tolerance

Tolerance refers to the amount of uncertainty (expressed as either a percentage of the

resistance value or as a temperature) to expect from a particular type of thermistor. For

interchangeable thermistors, tolerance is given over a specific range of temperatures (for

example, ±1%, or ±0.2°C over a range of 0 to 70°C).

You can also use non-interchangeable thermistors with far looser tolerances (for example, 5%

or 20%), however, then you will be required to perform your own temperature calibration (see

1 2 ... 88 89 90 91 92 93 94 95 96 97 98 ... 102 103

Sem comentários

ACR Electronics SmartReader Plus Manual do Utilizador Página 93