8
System 350
A350P Electronic Proportional Plus Integral Temperature Control Product/Technical Bulletin
A
djustments
Follow this procedure to set up the A350P control for
the types of operation desired.
1. Remove its cover by loosening the four captive
cover screws. (See Figure 2.)
2. Set the RA/DA operation jumpers to the desired
mode of operation. Position the operation jumpers
vertically for RA (Reverse Acting) or horizontally
for DA (Direct Acting). (See Figure 2.)
3. Adjust the throttling range potentiometer to desired
setting. Rotate Clockwise (CW) to increase the
throttling range.
Notes: Included with the control is a Celsius scale
throttling range decal. If the Celsius scale is
desired, refer to the
Celsius Scale Conversion
section for decal installation instructions.
If the A350P is to be used in proportional plus
integral control, the initial throttling range
adjustment is seldom set below 6F° (3C°).
A narrow proportional band used in
conjunction with the integration may result in
unstable control.
4. If minimum output is required, set the minimum
output potentiometer (see Figure 2) to the desired
position. The 10-segment front LED panel or a
voltmeter can be used to read the minimum
output. (The minimum setting for the
control
is
designated by the 0 on the decal.)
Notes: Before adjusting the minimum output
potentiometer, verify that the control reads
zero output (that is, no LEDs are lit).
For each 10% increase in output, the
next
bar will light on the LED bar graph (only
one bar is lit at anytime). In a milliampere
application, each bar equals 2 mA. In a
voltage application, each bar equals 1 VDC.
(Refer to Figure 3.)
Example:
To set the control for a minimum output of
4 mA, turn the minimum output potentiometer
clockwise until the second LED segment just
lights.
5.
Make sure the system is stable in the proportional
mode before selecting integration. Refer to the
Checkout Procedure
section.
6.
Reinstall the cover and secure in place with the
four captive cover screws.
7.
Adjust the setpoint dial to the desired setpoint.
If using the D350 Display Module, press and hold
the setpoint button on the D350 while rotating the
setpoint dial.
Note:
The control’s setpoint is factory calibrated at
midscale to a tolerance of ±1F° (0.6C°). The
setpoint tolerance at the extreme ends of the
setpoint scale may be ± 4F° (2.2C°). The
D350 Display Module is unaffected by this
tolerance shift. Use the D350 for the most
accurate setpoint selection.
C
heckout Procedure
Follow this procedure to verify the A350P control is
connected and functioning properly.
1.
Before applying power, make sure that the
installation and wiring connections are according
to job specifications.
2.
Set up the system for proportional mode
(Integration = OFF), and make any necessary
adjustments to the setpoint, throttling range, and
minimum output. Then select Reverse or Direct
Acting mode.
3.
After making adjustments and electrical
connections, apply power to the system, and
observe it for stable operation.
4.
If integration is required, select the fast (C1),
medium (C2), or slow (C3) integration constant.
Slow is the recommended initial setting. (Refer to
the
Integration Function
section.)
5.
Put the system back into operation. If instability
occurs, consider increasing the throttling range.
T
roubleshooting
If the control system does not function properly, verify
that the proper operation mode is selected on each
module (DA or RA), and perform the following
procedures to determine the cause of the problem:
1. Check for proper voltages on the A350P control.
a. Connect a digital voltmeter (DVM) between
Terminals 24V (+) and C (-) located on the
A350P’s terminal block. (See Figure 2.)
If an external transformer is used, select AC
volts on the DVM. Verify that the voltage is
between 20 and 30 VAC.
