Servo Motor Speed Adjustment (Av4); Servo Motor Speed Adjustment (Coarse And Fine) - ABB AV3 Instruction Manual

3. Slide the span adjustment assembly in the appropriate direc-
tion in order to align the 100% radial line with the center of the
cam roller (toward pilot valve increases span of actuator).
4. Tighten the span adjustment screw.

SERVO MOTOR SPEED ADJUSTMENT (AV4)

The speed of the pulse to pneumatic (P/P) converter can be
adjusted with the coarse and fine speed adjustments located on
the EMI/electronics housing enclosure (Fig. 4-3). Speed in this
case is defined as the time it takes the P/P converter to make a full
scale 20.4 to 103.0 kilopascals (three to 15 pounds per square
inch gage) or 103.0 to 20.4 kilopascals (15 to three pounds per
square inch gage) signal change.
Ideally, the speed of the converter should match the stroking
speed of the actuator. A converter speed faster than the actuator
can cause actuator overshoot. However, actuator stroking speed
is typically not precisely known and is affected by temperature and
load variations. Therefore, in applications that are not critical, the
P/P converter should be set to a speed somewhat slower than the
actuator speed.
Servo motor speed has coarse and fine adjustment provisions.
Coarse adjustment is made using a four position switch. Fine
adjustment is made using a 20-turn potentiometer. Table
the switch positions, factory set speed and speed range for each
switch position.
Table 4-1. Servo Motor Speed Adjustment (Coarse and Fine)
Coarse Adjustment
Switch Position
4
3
2
1
In applications where stroke speed is critical use the following pro-
cedure to match actuator stroke speed with the servo motor
speed.
1. Set the COARSE adjustment to 1 (Fig. 4-3).
Fine Adjustment
Factory Set Speed
(seconds)
26.0
13.5
8.0
5.0
GENERAL CALIBRATION
CALIBRATION
4-1 lists
Speed Range
(seconds)
21.0 to 42.0
12.0 to 22.0
7.0 to 13.0
4.5 to 8.0
4 - 5