24
MOTOR ADJUSTMENT
Control Direction
It is necessary to ensure that each motor travels in the correct direction when moved using the
UP/DOWN
keys on the keyboard. To do this, follow the procedure below.
1.
Enter commission ratio mode.
2.
With the display showing P0, use the
UP/DOWN
keys to move each motor. If the displayed
position decreases as
UP
is pressed, or decreases as
DOWN
is pressed, reverse the motor output
UP/DOWN
connections.
Check that when the
DOWN
key is pressed, each motor moves its valve towards the closed position.
Feedback Potentiometer
The servo-motor internal feedback potentiometer must be secured within the servo-motor to
ensure that there is no possibility that the potentiometer can become disconnected from the
motor output shaft.
For each motor, it is necessary to adjust the potentiometer's position relative to its shaft in order to
obtain the correct open and closed positions on the display. To do this, follow the procedure below:
1.
Move the valve to its fully closed position and adjust the potentiometer's position on the motor
shaft so that approximately 1° is shown on the display.
2.
Move the valve to its fully open position and check that the display reads approximately 90° or
the maximum angular opening required from the servo-motor if this is less than 90°. If the dis-
played position decreases as the valve is opened, reverse the supply connections to the feedback
potentiometer. If the displayed position range is incorrect, check that the correct potentiometer
supply voltage has been selected.
Adjusting Microswitch Positions
Each time a burner start-up sequence is initiated, the unit will move the fuel and air damper motors to
their closed and purge positions to prove correct motor and potentiometer operation. Each motor
must have microswitches fitted to limit the close and purge positions obtainable during this proving
operation. To set the microswitch positions, follow the procedure below.
1.
Enter commission ratio mode
2.
Move each motor to approximately 45°, either by hand or using the
UP/DOWN
keys.
3.
Holding the
DOWN
key, tighten up the low limit microswitch until the motor will no longer
move down.
4.
Holding the
DOWN
key, gradually slacken off the low limit microswitch until the motor starts
moving down. Continue to slacken off the microswitch until the motor stops with a reading on
the display of approximately 2°.
5.
Move the motor up and down a few times to check that the motor stops each time at approxi-
mately 2°, and re-adjust the microswitch if necessary. This position will allow for some toler-
ance in microswitch operation.
6.
Hold the
UP
key and tighten up the high limit microswitch until the motor will no longer move
up.
7.
Holding the
UP
key, gradually slacken off the high limit microswitch until the motor starts mov-
ing up. Continue to slacken off the microswitch until the motor stops in the desired purge posi-
tion. This position does not have to be 90°, but it is recommended that it is more than 45°.
8.
Move the motor up and down a few times to check that the motor stops each time at the desired
purge position. Repeat steps 3 to 7 if necessary.
