There is a programmed power interruption for Jul. 21 (Wed.), 1999
in order to change the ball bearings on the Piller rotating element
that guarantees transition from unprotected power to UPS.
Ing. Fulgenzi has already announced this interruption a month
ago and we finally fixed this date (Jul. 21) as the one to perform
this operation. Contrary to what it was thought at first, the
intervention will last 1 day only (instead of 2-3).
Today, we discussed the alternatives of providing electrical
power during this intervention. Since the possibility to provide
another UPS was out of question (too few days and an enornous effort
to accomplish it), we asked for a power switch that will interrupt
power in case of a glitch and thus protect our electronics from the
catastrophic effect of sudden power-on.
This switch can be installed, but we need to specify the duration
of the power glitch in order for the switch to go off. This is
expressed in msecs, and (as a point of reference), Ing. Fulgenzi
said it is usually set at 50msec, in case of power provided to computers.
We, from the point of view of the scintillator electronics, would
like to use the value indicated by our LeCroy PMT HV power supplies
(that have a similar switch to guard against power glitches).
I invite the streamer-tube experts to give us their opinion ASAP
since Ing. Fulgenzi needs to regulate the power switch before installing
it on MACRO.
A presto,
Ioannis Katsavounidis