Watlow QPAC-01 - Page 26

Starting Out
26
QPAC User's Manual
How to Operate QPAC, Chapter 3
1. Connect a volt meter across the load or dummy load of the QPAC. Connect
a volt meter across, or milliamp meter in series with, the input signal from the
temperature controller. NOTE: AL card should be calibrated with a dummy
load on the QPAC
2. Apply power to the system.
3. Set the output signal of the temperature controller to zero or its minimum
output. The QPAC input is factory calibrated for full off at 4.2 mA. Adjust the
bias potentiometer slowly CCW (counterclockwise) until the QPAC output just
comes ON. Then turn CW (clockwise) until the output is just full OFF as
observed on the output volt meter. See the following figures for the location of
the bias and gain potentiometer on the Control Cards.
NOTE: The QBV card does not include a bias adjustment. A bias and gain
adjustment card can be added to the QBV card in the field. Order Watlow part
number 08-7210. Follow this calibration procedure when using the bias and
gain card.
4a. AF & BF: Adjust the output of the temperature controller to full ON (5VDC,
20mA, etc.). Adjust the gain potentiometer CW until the QPAC output is just
full ON. The QPAC is factory calibrated to be full on at 19.8 mA.
4b. BV & AL: Adjust the output of the temperature controller to full ON (5VDC,
20mA, etc.). Adjust the gain potentiometer CCW until the QPAC output is just
full ON. The QPAC is factory calibrated to be full on at 19.8 mA.
5. When adjusting the bias and gain of the current limiting (AL) control card,
ensure that the current limiting is turned OFF. With the output of the tem-
perature control full ON, adjust the current limit potentiometer until the QPAC
output is full ON.
6. Repeat steps 3 and 4 until the QPAC turns full ON with a full ON signal from
the temperature control, and full OFF with the minimum input signal from the
temperature control. Steps 3 and 4 may need to be repeated a few times (an
adjustment made on one of the potentiometers affects the adjustment of the
other potentiometer).
7. Remove power, disconnect the meters, and reconnect the controlled load to
the QPAC if required.
Bias & Gain
Figure 34 -
AF (Rev. H)
Control Card
Figure 35 -
BF (Rev. D)
Control Card
Gain
Pot
Bias
Pot
08-5288
1
5
TB-2
R39
R38
TB1
4-20mA
5V
Gain
Pot
Bias
Pot
08-5289
R17
1
5
TB-2
R3
TB1