-----------
1 r 500
AUTOGRAF
INPUT PANEL
------
ALLEN- BRADLEY
POTENTIOMETER
Test Rig, Fig. 12
Gain limits are usually fixed by the following factors:
a. Gain too low:
Servo "dead zone" resulting in excessive "retracet1 or space between the
l'upll trace and the lldownll trace.
b. Gain too high:
Recorder jitters or oscillates at high frequencies with small amplitude.
In order to check damping a more rapid variation of recorder input may be
utilized. Apply a constant voltage to one axis, while flipping the attenuator
switch between two adjacent positions or use a square wave input, while
spreading the graph by rotating the zero control of the other axis.
Damping limits are usually indicated by the following factors:
c. Damping insufficient:
Excessive overshoot and oscillation (jagged "teeth" in square wave
pattern) .
d. Damping excessive:
Sluggish, lagging response, resulting in less than optimum reproduction
of the input waveform (excess rounding of square wave).
A recorder which is performing properly will have a low llstand-byll voltage
supplying each of its servo motors. This may be verified by placing an AC
29 |
ACEC
