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73VR2102 / 73VR2104 / 73VR2106 / 73VR2108 / 73VR2110 / 73VR2112 USERS MANUAL EM-7395-B Rev.24
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STABILIZING COLD JUNCTION COMPENSATION
• Sudden ambient temperature change could increase the cold junction compensation error by the internal terminal
temperature sensor. Please take the following precautions to prevent it.
• Be sure to close the terminal cover when operating the 73VR21x.
• Stabilize the temperature around the terminal block. DO NOT expose the terminal block in the direct line of air flow
from air conditioners, cooling fans, or ventilation fans. Switching on and off the fans located close to the terminal
block affects the ambient temperature.
• Disposition of the terminals for odd-number channels is tend to be more favored in the CJC stability than those for
even-number channels.
• Resistor modules (model: REM3-250) can be connected to the 73VR21x to convert current inputs into voltage.
However, it is not recommended when TC inputs are mixed because the heat developed on and around the REM3
affects the cold junction compensation performance. We recommend that REM3 be connected on a separate terminal
board.
• Do not use wires of large diameter which has large heat dissipation. We recommend using the wires of 0.5 mm
2
(AWG 20) or thinner diameters not only for the thermocouple channels but for all other screw terminals.
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CONNECTING OTHER DEVICES IN PARALLEL
• Turn off the burnout function for thermocouple inputs.
• No parallel connection is permitted for RTD inputs.
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DO NOT APPLY OVERRANGE NORMAL MODE VOLTAGE
• Do not apply voltages exceeding ±20V to terminals B – C for ±3V, ±6V or ±12V ranges to prevent damage.
• For other ranges, do not apply voltages exceeding ±12V to the same terminals to prevent damage. Applying voltages
exceeding ±1.5V may affect the measuring accuracies of other channels.
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INTERNAL CLOCK
• The internal clock data is stored in memory powered by a backup battery while the 73VR21x is without external power
supply.
• The data will be reset to its default status when the battery is used up while the 73VR21x is left without power sup
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ply for a long time period. The clock adjustment will be necessary once the power is restored. Please refer to the
73VR21x Users Manual for the procedure.
• Once the power is restored, the 73VR21x starts recharging the battery. It will be full in approximately in 36 to 48
hours.
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AND....
• We recommend use of an UPS (switching time: without delay, output: sine waveforms) to supply power backups.
• The module is designed to function as soon as power is supplied, however, a warm up for 10 minutes is required for
satisfying complete performance described in the data sheet.