Adjusting Rear Door Height
- Gary Foster
- Karl Newman
The Rear Door uses two 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.
The servos do not know actual position of left and right sides of the door. Servos only know actual motor rotor position.
Indications of proper Rear Door alignment
Left and right drive chains should be under equal tension so that each chain carries part of the load.
Door should not shudder during operation.
Left and right tensioner sprockets should be at equivalent distance from limit switches.
Neither tensioner sprocket should be near the limit switch.
Left Rear Door guide should ride near the center of the track; not dragged to either side.
Drives should not trip on overcurrent.
Probable Causes for Rear Door misalignment
If the Rear Door is closing (moving down) the motor cannot drive the door down. It only controls speed of the door falling due to its weight. If the door jams in the slide the motor will continue to rotate and move its drive chain. Since the door is jammed it 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.
If the Rear Door Seal breaks, seal material can become lodged between the slide and the door. Since the only force on the door in the closed direction is gravity, the door can jam and stop moving. The door will bind.
Aligning the Rear Door
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
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:
Using the EMCS 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 Rear 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.
When rear Door adjustment is done, restore Normal Rear Door operation
Click ‘Maintenance Mode’ button to turn Maintenance Mode OFF.
Power cycle the control unit. Otherwise there is the possibility that the offset between the two sides will be “remembered” and it will move one side out of alignment again when jogged.
Confirm that the Rear Door is aligned:
Operate Rear Door using Cabinet 406 Local Jog Buttons.
Verify proper Rear Door operation.
Using Starter instead of the HMI
Refer to:
Siemens Starter must be installed on your computer.
Double-click the Rear Door drive configuration file (.s7p) in Rear Door S120 Drive configuration. Starter will open the configuration file.
Connect ethernet cable between the computer and the Rear Door drive control unit in Cabinet 406
Change your computer IP address to (169.254.11.1, subnet mask 255.255.0.0) to be on the same subnet as the Control Unit.
Connect to the Control Unit
If you cannot connect, check and fix the communication settings.
On the Project Navigator: Double-Click Drives > Servo_02 (or Servo_03) > Commissioning > Control Panel
Assume control of the selected drive.
Then:
Click to Display Diagnostics View
Click Enable
Click Infeed Control Priority
Before starting the motor :
Enter a speed setpoint (e.g. 50 revolutions per minute).
Use the slider to set the setpoint in %. Position your cursor on the slider, hold down the left mouse button, and set the speed to 0%.
Click Drive ON.
Move the slider for the speed slowly to increase speed.
Click Drive off to stop the motor. You can also trigger a fast stop by pressing the <space bar>.
Adjust Rear Door height as described in ‘Aligning the Rear Door’.
When Rear Door adjustment is done, restore Rear Door Drives to normal operation
Click Infeed Priority
Click Return... to terminate the connection to the drive unit.
Click OK to return control priority
Power cycle the control unit. Otherwise there is the possibility that the offset between the two sides will be “remembered” and it will move one side out of alignment again when jogged.
Confirm Rear Door operation as described above in 'Confirm that the Rear Door is aligned'.