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Last changed:
IS 2009-10-21 Clearified a bit.
IS 2012-03-19 Relaxed a bit due to new altaz and building drives.

How to deal with a power cut

This applies only if the power cut appears when the telescope is powered on.

In case of an external power cut, indicated by the warning message 'Security: NO EXTERNAL POWER! Notify duty staff.' and that ventilation in the control room stops, there is no power to the cooling system but the big UPS supplies the telescope with battery/diesel generator power. That means that the telescope drive system will get heated up together with all equipment in the electronics room. You can contact duty staff and notify if the power cut lasts. Usually nightly power cuts are short, so they do not effect the observing, the TCS and its subsystems will continue to function. When the power is back again the (friendly) error message 'Security: External power is back again.' appears and ventilation in the control room starts again. If the power cut lasts for many minutes please do the following:
You are recommended to within 5-15 minutes save the ongoing exposure, put telescope to zenith and power off. After a while the error message 'Security: TEMPERATURE IN ELECTRONICS ROOM TOO HIGH!' might show up. If You still have not gone to zenith and powered off then do it now! The new altaz drives should be ok and the building drives also, but the rotator amplifiers could be sensitive.
There could also be an automatic cut of the safety system if the temperature in the electronics room raises further, caused by a thermostat. There is a temperature display on top of rack 23 (last one to the left), have a look at that.
When the message 'Security: External power is back again.' appears then check the temperature on rack 23 until it is down to about 24 degrees, then You can power on and continue to observe.
Note that if external power is only gone a few minutes there is usually no need to take any special action. In very rare cases Residencia staff might warn for a coming power cut, then just do as described above.
Please note the power cut down in the EON report.

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