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AdV-COM (AdV commissioning (1st part) )
ruggi - 16:50 Monday 13 May 2019 (45878) Print this report
Lock in windy condition

When the wind is strong the main cause of lockloss is the saturation of NE/WE MAR actuation. This is the same situation generated by a strong earthquake, and the solution is the same: move the marionette reallocation to NI/WI. In order to understand what is the tolerable limit, we can look at the figure: if wind gusts can overcome 50 km/h, NE/WE MAR CORR can easily reach the saturation (2.5 V, because of the factor of 4 applied before the DAC). In the period shown in figure the correction was not actually applied, because the reallocation was moved to NI/WI. Staying on NE/WE, the lock would have been lost at least twice.

Therefore, it would be better to translate this warning in a procedure:

IF THE WIND SPEED EXCEEDES 50 km/h, APPLY THE SAME PROCEDURE AS FOR A STRONG EARTHQUAKE.

Concerning the application of this procedure, there is a problem: if we start in LN3_SQZ, but an unlock of SQZ move the status to LN3, the automation put back the reallocation of NE/WE. The problem will be fixed as soon as possible.

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ruggi, nenci - 17:58 Monday 13 May 2019 (45880) Print this report

After 1/2 hour of wind well below the critical level, we decided to put back the standard MAR reallocation, in order to go in SQZ and SCIENCE. Unfortunately, the wind increased again, and it gave us not so much time to decide about the application of the safety procedure: a few minutes after the first crossing of the 50 km/h threshold, the killer gust came and unlocked.

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