And 3 Wire Rtd, Voltage, Current, Frequency And Resistance; Wire Rtd Sensor Calibration - Process Technology DQ15D Instruction Manual

temperature value for the connected precision resistors
(i.e. 511º F or 266º C).
Step 11: Turn OFF power and remove the precision resistors. Re-
install the RTD sensor and the rear cover of the controller.
Return the calibrated control to service.
2 and 3 Wire RTD, Voltage, Current, Frequency and
Resistance
Optional PCN 5447 or 5416 board needed.

3 Wire RTD Sensor Calibration

Note: For a 1000 ohm sensor, the DIP switches should be OFF, OFF, OFF.
For 100 ohm, check that the DIP switches are ON, OFF, OFF (see page 29).
This board will accept 2 wire RTDs as well. RTD devices are precision
resistors whose resistance value varies with temperature. The connec-
tion of a "third wire" eliminates the natural resistance of the lead wires to
improve sensor accuracy. The DQ15D control measures the RTD resis-
tance (and the third wire resistance) and compares that measurement with
a "standard" set of values stored in the control memory. To restore, up-
date or verify that this "standard" set of values is correct, do the follow-
ing:
Equipment needed:
1. Two precision resistors (tolerance +/- 0.1% or better) with a fixed
value equal to the nominal value of the RTD (i.e. 1000 ohms or
100 ohms).
2. A suitable jumper cable to facilitate changing input resistance.
3. A short piece of jumper wire (simulates third wire).
WARNING!
Calibration procedures require the removal of the rear cover of the
control. It also requires that power is ON, exposing the technician to
potentially lethal voltages. Exercise EXTREME CARE and wear
tested electrician's gloves whenever power is on.
Calibration procedure for the 3 Wire RTD:
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Step 1: Turn OFF all power.
Step 2: Remove rear cover.
Step 3: Remove RTD sensor.
Step 4: Install the short piece of jumper wire from terminal #1 to #3.
Step 5: Install the precision resistors in place of the RTD sensor,
as shown in terminals #2 and #3.
Step 6: Install the jumper cable between the loose end of one of
the resistors and the fixed end of the other resistor to
establish an input value of a single resistor (i.e. 1000
ohms or 100 ohms), as shown.
Step 7: Carefully restore power to the controller, ensuring that
you do not come in contact with any exposed voltage.
Step 8:
Press the increase " " and decrease " " keys simulta-
neously and hold for approximately 6 seconds. The dis-
play will indicate "AC.0". while the "0" is flashing, use
the increase key to change this to "22". Press the "SET"
key. The control display will read "CAL1". .
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