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WHT DOME ROTATION AND SHUTTER OPERATION



POWER SUPPLIES
    The power for the dome is supplied from the clip centre power distribution board in the WHT control room and is routed to the Dome Power Panel on the Nasmyth gantry before going to the respective systems. The Dome Power Panel houses the local switches for all power supplies to the Dome rotation, Top Shutters, Bottom Shutters, Cranes and Control Transformer.


DOME ROTATION & BOTTOM SHUTTER CONTROLS

     These are located behind the door of the DOME CONTROL PANEL CP1 which is situated on the Nasmyth gantry.



DOME ROTATION
    The Dome can be operated either from remote (computer control) or local position. The selector switch is located inside the DOME CONTROL PANEL CP1 and is key operated.
Local Control - This is achieved by turning the key operated switch to local control, push the 'Dome Motors Start' button then simply push the button for clockwise or anticlockwise rotation. The Dome will turn for as long as you hold your finger on the button. When finished be sure to press the motor stop button.

BOTTOM SHUTTER
    The shutter can be operated in either Main Drive or Microdrive by turning the key in the appropriate selector switch. With the shutters closed the bottom shutter can only be operated in Micro Drive until it is approximately 150mm away from the top shutter at which point the main drive can be selected. Before opening the top shutter you should always lower the bottom shutter first by 150mm, this ensures that when you close the top shutter it will close fully against the weather seal at the top of the dome. The bottom shutter can then be raised to form a seal against the top shutter. The shutter controls are such that they automatically switch off the power when the shutter has reached its full travel in its selected mode. If you should be operating in Main Drive you will find that the shutter will stop approximately 150mm from the top shutter and you will have to complete the closure in Microdrive.


TOP SHUTTER


             The controls for this shutter are located on the KONE panel which is located on the Nasmyth gantry a few metres to the left of the Dome Power Panel.

MAIN DRIVE OPERATION

  1. Switch the Main Isolator on by turning the switch to 'l' position.
  2. Select 'Normal Control' on the control selector switch.
  3. Release the Emergency stop interlock. This is done by turning the key and allowing the big Red button to spring out.
  4. Push the green button marked 'Main Cont', this should result in the green indication light being illuminated. If it doesn't check that the Emergency stop is fully out and that the joystick is in the central position before trying again.
  5. Wait a few seconds before operating the joystick to move the shutter. Failure to wait will result in the system locking out.
  6. The shutter can then be operated on the joystick. It requires little force to move the joystick and it should be operated gently - up to raise the shutter and down to lower it.


MODE SELECTION

MAIN DRIVE


AUX DRIVE


REMOTE CONTROL

MACHINERY SELECTION

This switch should not be interfered with, the normal position is I + II  MACH.A+B
       
NOTE:
    ALL OTHER POSITIONS ARE FOR MAINTENANCE ONLY AND ANY ATTEMPT TO RUN THE SYSTEM IN THESE OTHER POSITIONS WOULD RESULT IN SERIOUS DAMAGE TO THE DRIVE UNITS AND CABLES.

 
AUXILIARY DRIVE - EMERGENCY OPERATION

    If in the event of a failure of the Main Drive system it is necessary to use the Auxiliary Drive units to close the shutter then the following procedure will be required :-

Contact the Duty Officer for the keys to the Mode Selection switch which are held in DO's WHT keypress.
Put the key in the Mode Selection switch and turn so that the arrow on the barrel of the switch points to AUX DRIVE.
Provided the controls are available as described under Main Drive operation the shutter can then be operated by pushing the buttons marked AUX DRIVE DIR 1 or AUX DRIVE DIR 2 depending upon which direction you want to travel. The button must be pressed all the time you want the shutter to move.

-------- © 2007 Isaac Newton Group of Telescopes --------
Last Updated: 14 May 2007 Andrew Cardwell

Based on notes by R. Docherty from April 1992