[evlatests] Generator Utility Module
Sylas Ashton
sashton at nrao.edu
Fri Jul 13 11:50:25 EDT 2012
Previous tests using the remote start feature of the Generator Utility
Module caused the module to stop communicating, once at 20 minutes after
the generators started and once 90 minutes after the generators started.
The suspected cause of the problem is extra noise coupled onto the 24V
power to the generator by the remote start line. Several weeks ago, we
added a 100ohm series resister into the line inside the module. Since
the site load was too high that day, we were unable run tests that day.
On Wednesday, connected a debugger to the MIB and ran the tests.
During the first test, the module was reset when one of the relays
engaged during the generator startup sequence. Fearing a new failure
mode, we went through the remote startup sequence a total of 5 more
times, and could not replicate the new error. After one of the remote
starts, we left the generators running for 90 minutes. Module did not
lose communications the rest of the day.
The original problem appears to be solved. The one glitch we did see may
have been caused by EMI pick up by the debugger cable connected to the
MIB while a large relay switched.
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