Extech Instruments PRC70, Руководство пользователя

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7.5.1 Temperature (TC) Monitor Function
The calibrator offers a temperature monitor function convenient for observing the voltage value sourced between the output
terminals in TC source mode. In the TC source mode, press the
(START) key and the LCD will show the voltage value
sourced between the output terminals (this value varies in response to the changes of the reference junction compensation).
Press the
(START) key again and the LCD will show the preset temperature value.
7.6 Sourcing RTD Temperature
z First, the calibrator sources a resistance signal by receiving the resistance-measuring current (I) supplied from the
device being calibrated (such as a resistance meter) and then delivering the voltage (V) proportional to the preset
resistance (R) between the output terminals, and thus producing the equivalent resistance R =V/I. Consequently, the
calibrator sources the signal correctly only for such devices that employ this method of measurement.
z The allowable range of the resistance measuring current that the calibrator receives from a resistance measuring device
under calibration is rated as 0.1 to 3 mA. To ensure accuracy, the resistance measuring current from the device under
calibration is strictly confined within this range. For further details, see the “Specifications” section.
z
Sourced resistance signals do not include the resistance component of the lead cables. The entire resistance, when
measured at the ends of the lead cables for sourcing, is given by adding the resistance of the lead cables
(approximately 0.1 ohms) to the sourced resistance signal. For the sourcing of precise resistance signals, use three-wire
or four-wire connections.
Step 1:
Using the function key (FUNC) , select the RTD function. Using the (RANGE) key, select a RTD range (PT100,
PT200, PT500, PT1000, Cu10, Cu50). The selected function, the default range source value, and the unit of measure are
shown in the lower area of the LCD.
Step 2:
Set the output value digit by digit using each pair of
〔
S
〕
/
〔
T
〕
keys.
Each press of the 〔
S
〕 / 〔
T
〕 key increases or decreases the digit. Increasing the digit from 9 or decreasing it from 0
causes the digit to overflow or underflow, allowing the output value to be set without interruption. Holding down the
〔
S
〕
/
〔
T
〕
key changes the digit in question quickly. And the value won’t change if it is increased or decreased to the Maximum or
Minimum value. Pressing the (ZERO) key initializes the output set point to the default value (0).
Step 3:
Pressing the (ON) key causes the SOURCE indicator on the LCD to change from ‘’OFF‘’ to ‘’ON ‘’. The calibrator
sources the preset resistance value between the output terminals.
Step 4:
To switch OFF the output, press (ON) again. The ‘’OFF‘’ icon appears on the LCD and no signals are sourced
between the terminals. The connection methods based on three-wire and four-wire are shown in Figure 9.
Note:
The RTD source function is unavailable if the TC /RTD measurement function is ON.
7.6.1 Temperature Monitor Function
The calibrator offers a temperature monitor function for easily observing the resistance value sourced between the output
terminals. In the RTD source mode, press the
(START) key and the LCD will show the resistance value sourced between the
output terminals. Press (START) again and the LCD will show the preset temperature value.