Electronics AC-24 - Manual (Page 6)

6
K. CALIBRATION SPAN AND ZERO
1. The digital display (1-1) should show zero when the motor is turned off. If it does not
show zero then push the “zero” button (2-26) to achieve a zero reading.
2. The factory setting of input “Span” is 1000 (gain of 1.000). This represents the condi-
tion of 5.00 Amps as input signal and for a 100:5 current transformer the display should
show 100.0. This setting probably should not need customer adjustment. However, if
the digital display (1-1) does not correctly show true motor amps then you can change
the span setting by pushing Calib span button (2-25) and ▼ or ▲. The span setting
range is from 750 to 1500.
6. 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. However, since many factors determine
system stability, these adjustments should be made slowly.
B. SERVO GAIN - This adjustment sets the gain of the error amplifier over a range of 1% to
100%. Most systems may operate at 50%. If the motor the amps is unstable, then reduce
the gain to 25%
C. SERVO SPEED - This adjustment determines the speed at which the output signal in-
creases to achieve desired motor amps. A 50% value is set at factory for typical applica-
tions. Adjusting the servo reset higher á will make it go faster and adjusting it lower â will
make it go slower.
D. If the shot flow rate and motor amps is not steady it will be necessary to perform a simple
stability test. Place the servo (2-20 ) in its off position. Enable the control and slowly in-
crease the setpoint from 0% until the ammeter reads your desired operating value. If the
operation at this time is unstable, then it is the system that is unstable. Since the control is
in manual mode, if motor amps is unstable, then the motor or wheel is causing a problem,
not the servo adjustments (because the servo is off ).
E. Wheel condition can affect amperage stability.
1. Worn blades, blades with severe erosion, can cause unstable operation.
2. Worn control cage can cause unstable operation.
3. Misadjusted control cage can cause unstable operation.
4. Feeding more shot than the wheel can receive may cause unstable operation.
5. Refer to section 11 Trouble-Shooting Section.
7. MOTOR AMPS FULL SCALE DISPLAY
A. The factory has pre-set the span adjustment so that 5 Amps AC input will result in a full
scale display reading. To accommodate different ranges of current transformers such as
100:5 or 50:5 you need to change the Display Full-Scale Adjustments, not the span set-
ting.
B. The standard factory setting is for 100:5 current transformer. To use other current trans-
former ratios proceed as follows:
C. Push the Display Range Coarse button (2-28) and read the value in the display. The fac-
tory setting is 100.0.
D. To increase or decrease the full scale range use the ▼ or ▲ buttons.