(In progress)
The Rear Door uses two motors, operating independently. These are induction motors operating in servo mode. They are commanded to run the same speed, and they usually do. But the drives are not synchronized. Sometimes the motor positions become too far apart and the door binds.
Probable Causes for Rear Door misalignment
If the Rear Door drives are misaligned, Investigate the Rear Door drive mechanisms to determine what caused the door to lose alignment.
The servos do not know actual position of left and right sides of the door. Servos only know actual motor rotor position.
Typical causes:
If the door is closing (moving down) the motor only controls speed of the Rear Door falling due to its weight. If the door jams in the slide the motor will continue to rotate and move its drive chain. but the door is jammed and does not move. The motor pulls chain from above until the tension becomes so high that the chain skips on the drive gear, or something breaks.
Realigning the Rear Door
To realign the left and right sides of the door one drive must be enabled and the other drive OFF.
There are two ways to do this:
Prepare the Rear Door for operation
Verify Rear Door left and right motor tensioners are free to operate and are not at end of travel.
Cabinet 406 Main circuit breaker closed
Cabinet 406 selector switch in Local Mode
Rear Door seal deflated
Trapped key L inserted and rotated in Cabinet 406 door.
Emergency stops reset and armed.
GIS Reset
EMCS Reset
All hands clear of the door and clear of the safety sensors
Using the ENCS HMI
Launch the EMCS HMI.
Log in. To operate the rear doors independently, your EMCS user account must be authorized for RearDoor operation.
At the EMCS HMI Main screen: click on ‘Rear Door Drive Status’
Click ‘Maintenance Mode’ button to turn Maintenance Mode ON. This allows operation of only the selected motor so that the opposite motor will not attempt to maintain position (as servo motors do).
Aligning the door
Measure Rear Door position on left and right sides. Decide how far to move either side to bring the door back to level.
Note the Actual Position o the side you intend to adjust.
Actual Position is scaled ~26,500 LU / inch of travel. LU = Load Unit which is an arbitrary measure used by the S120 drive.
Jog the selected side up or down. Jog buttons are momentary contact. Hold the mouse button down to cause the motor to move. Movement is very slow.
Jog until left and right sides are at same height above the deck.
To confirm if the door is aligned:
Click ‘Maintenance Mode’ button to turn Maintenance Mode OFF.
Operate Rear Door using Cabinet 406 Local Jog Buttons.
Verify proper Rear Door operation.
Using Starter instead of the HMI
Launch S120 Starter on a computer.
Connect ethernet cable between the computer and the Rear Door drive control unit
Take local control of one drive.