Inficon SQC-310

7 - 9
PN 074-550-P1C
SQC-310 Operating Manual
6 Slowly rotate the control knob to a power of 10%, and verify that the power
supply output is about 10% of full scale. Continue to slowly rotate the control
knob until a rate near the desired setpoint is achieved.
 Verify that the power supply output agrees with the SQC-310 Power (%)
reading. If the readings are not the same, check the wiring and verify the
source setup in the System menu. Confirm the Voltage Scale agrees with
the input specifications of the power supply.
7 With the power set so the rate is near the desired rate (Init Rate in the Quick
Edit menu), Press Next Menu then Next Graph until the Rate Deviation graph
is displayed, and observe the noise.
 If the system has significant short term noise at fixed power (approximately
>10%), the control loop will be very difficult to adjust, especially at low rates.
It is better to eliminate the source of the noise before attempting to set the
PID values ( see section 6.1, Troubleshooting Guide, on page 6-1.)
8 Select a new Filter Alpha
On the Quick Edit Menu:
 Slowly decrease the filter Alpha from 1 to a lower value until the rate display
noise is minimized. If the Filter Alpha is set too low, the display will lag the
true system response and may hide significant problems. A value of 0.5
equally weights the current reading and the previous filtered readings.
9 Determine Max Power
 With the desired rate at a stable reading, record the power (%) (PWR
DR
)
value. Set the Max Power (%) to a value 20% higher than this value.
10 Determine Open Loop Gain
 With the power (%) at the desired rate (PWR
DR
) recorded, slowly lower the
power(%) until the Rate (
Å/s) reading is just at (or near) zero. Record the
zero rate Power reading (PWR
0R
) or P-Term parameter.
11 Determine Open Loop Response Time
 Calculate 1/3 of the desired rate (RATE
1/3
), and 2/3 of the desired rate
(RATE
2/3
) for this film.
 Slowly increase the power (%) until Rate (
Å/s) matches RATE
1/3
.
 Quickly adjust Power (%) to PWR
DR
. Measure the time for the Rate (Å/s)
reading to reach RATE
2/3
.
NOTE: This may need to be done several times to get an average response
time. Displaying the Rate graph will also help.
 Twice the measured time is the step response time (TIME
SR
) or the I-Term
parameter.