Watlow QPAC - Manual (Page 22)

22 QPAC User's Guide Chapter 3: How to Operate
1. Connect a volt meter across the load or dummy load of the QPAC. Con-
nect 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 4.2mA. 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 and BF: Adjust the output of the temperature controller to full on
(5Vdc, 20mA, etc.). Adjust the gain potentiometer CW until the QPAC out-
put is just full on. The QPAC is factory calibrated to be full on at 19.8mA.
4b. BV and 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
19.8mA.
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 temper-
ature 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 and Gain
AF (Rev. H) Control Card.
BF (Rev. D) Control Card.
Gain
Pot
Bias
Pot
08-5288
1
5
TB-2
R39
R38
TB1
4 to 20mA
5V
move jumper for mA or volts dc input
Gain
Pot
Bias
Pot
08-5289
R17
1
5
TB-2
R3
TB1
cut resistor R3 for volts dc input