Novus LogBox Wi-Fi Instruction Manual page 52

Thermocouples: The analog input circuit for the LogBox Wi-Fi guarantees the accuracy specified in the Thermocouple sensors reading with a
maximum cable impedance of 100 Ω. Thermocouple sensors with impedance above 100 Ω are read by LogBox Wi-Fi. Accuracy, however, is not
guaranteed. For reading the thermocouple sensors, the LogBox Wi-Fi uses the internal temperature sensor for Cold Joint compensation (NTC).
Just as with the internal temperature sensor, thermocouples may present a greater error than specified when there are sudden variations in
ambient temperature. The specified accuracy is only guaranteed when the device is installed in an environment with a stable temperature for a time
greater than one hour.
Pt100: The LogBox Wi-Fi analog input circuit guarantees the accuracy specified in the reading of PT100 type sensors with a maximum cable
resistance of up to 25 Ω. The device can read sensors with cables that have resistance above 25 Ω. In these cases, the accuracy and
measurement range are not guaranteed. The LogBox Wi-Fi performs the cable resistance compensation internally, if it is the same in the three
wires that connect the device to the sensor.
Linear 0 to 50 mV: The analog input circuit of the LogBox Wi-Fi guarantees the specified accuracy when reading electrical quantities of voltage
type 0 to 50 mV with a maximum cable impedance of up to 100 Ω. Voltage sources with series impedance above 100 Ω can be read by LogBox
Wi-Fi. Accuracy, however, is not guaranteed.
Linear 0 to 5 V and 0 to 10 V: The analog input circuit of the LogBox Wi-Fi guarantees the specified accuracy when reading electrical quantities
of voltage type 0 to 5 V and 0 to 10 V with a maximum cable impedance of up to 200 Ω. Voltage sources with series impedance above 200 Ω can
be read by LogBox Wi-Fi. Accuracy, however, is not guaranteed.
Linear 0 to 20 mA and 4 to 20 mA: All LogBox Wi-Fi input channels have common ground with each other as well as with the power supply
source. Thus, for the LogBox Wi-Fi to be able to correctly measure the current transmitters, it is necessary that they are fed by isolated sources or
by using all current transmitters with the interconnected earth.
Digital Input: All LogBox Wi-Fi input channels have common ground with each other as well as with the power supply source. For the LogBox
Wi-Fi to correctly measure the Digital Input sensor, such characteristic must be considered. For the logic levels of the sensor connected to the
digital input to be correctly detected, it is recommended that the maximum series impedance with the sensor is less than 10 kΩ.
Internal Temperature Sensor: The LogBox Wi-Fi has an internal temperature sensor of the NTC type that can be used for monitoring the ambient
temperature. This sensor is used for the Thermocouples Cold Joint compensation. Because it is located inside the device's casing, it may present a
greater error than specified when there are abrupt variations in ambient temperature. The specified accuracy is only guaranteed when the device is
installed in an environment with a stable temperature for a time greater than one hour. The sensor allows readings in a range of -40 °C to 125 °C.
The temperature, however, is limited to the device's operating range.
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