Electronics FC-24 - Manual (Page 5)

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Changing the set point to 15 would change the alarm trigger points to 14 and 16 pounds/
minute automatically. The alarm bandwidth of ±1 stays fixed until the alarm bandwidth is
changed.
G. If the Alarm Mode is set for percent of point (PT) as indicated by LED (2-15) then, with 5%
of point mode the alarm band diminishes as the flow setpoint is reduced. For a full scale
range of 20 lb/min and a setpoint setting of 20 lb/min the alarms will activate at ± 1.0 lb/
min. If the setpoint is reduced to 5.0 lb/min, then the alarm band automatically changes to
± 5% of that value or ± 0.25 lb/min.
H. ALARM TIMER - When the control is "Enabled" and in automatic servo mode, the
"High" (1-2) or "Low" (1-3) alarm light will come on if the flow rate goes above or below the
alarm limits. An adjustable timer, labeled "ALARM DELAY” (2-17), which is adjustable
from 0 - 10 seconds, will start each time the "High" or "Low" light comes on. If the fault
lasts longer than the timer setting the high (or low) light will get brighter and the high (or
low) alarm relay contact will transfer and latch. The alarm will stay on after the “Enable”
signal is removed until the alarm is reset, either by a remote “Alarm Reset” 24Vdc signal or
application of the next “Enable” signal.
I. ALARM RESET - Activating the alarm-reset circuit (24Vdc applied to Terminal #12) will
cancel the alarm relay and the alarm "high" or "low" LED's will go off. Continuous applica-
tion of the reset signal will disable or inhibit the alarm output signal. The alarms are auto-
matically reset upon receipt of each new "Enable" command.
J. REMOTE SETPOINT - A remote set point command may be used by pushing button (2-
27) until the “Remote” LED (1-9) is on. Apply a 0 - 10 Vdc analog remote set point com-
mand signal to the remote input, Terminal #2. A Zero Volt dc signal will correspond to a
0% flow rate command and a 10 Vdc signal will correspond to a 100% flow rate. To verify
the remote set point command, push button (1-8). The remote command may come from
a remote potentiometer or any 0 - 10 Vdc signal source.
K. RECORDER OUTPUT- An analog voltage recorder output signal, Terminal #18 with a 0 -
10 Vdc range is available to operate a strip-chart recorder or analog input card in data log-
gers. The minimum load on this output is 10K Ohms. Shielded cable (20 AWG or larger
gage) should be used and the shield should be connected to rear chassis of the FC con-
trol. This analog output signal is heavily filtered with a capacitor to provide noise immunity.
Additional electrical noise filtering may be necessary at the input terminals of an analog
input card to prevent erroneous readings.
L. MAGNAVALVE OUTPUT- During operation of the MagnaValve a bar graph display ( 2-13 )
will indicate the servo command output signal sent to the MagnaValve. The MagnaValve
also has an LED on its valve driver junction box to show this function. This LED will pulse
at approximately 10 Hertz with the duty cycle (on time to off time ratio) proportional to flow
rate. A low duty cycle will provide a low flow rate and the Valve LED will be relatively dim.
A long, or continuously on, duty cycle will provide a high flow rate. At 100% duty cycle the
Valve LED is constantly on and the permanent magnet field is completely canceled. Shot
will fall freely through the valve.
7.STABILITY ADJUSTMENTS - (SERVO STABILITY)
A. The servo adjustments have been factory set to typical settings and the customer may fine
-tune to optimize the speed of response if desired. Since there are many factors that deter-
mine system stability, these adjustments should be made slowly. Use the “Servo Gain” (2-
23) and “Servo Speed” (2-24) buttons along with ▲or ▼ to change the servo response.
B. If the shot flow rate cannot be stabilized, it will be necessary to perform a simple test. Turn
the servo “Off” using button (2-20). Enable the control by pressing the “Mode” button (2-
22) until the “on” LED is activated and slowly increase the set point from 0% until the flow