Lightning damage on Sept 27

Sept 29

A lightning strike on the afternoon of Sept 27 knocked out power to the base trailer and damaged equipment on the 20m main tower.

In the real-time archive, the DSMs at the main tower ceased reporting on Sep 27 21:03:05 UTC (15:03:05 MDT).

Station 12 also quit reporting at that time. A TRH and barometer at C20 and a TRH at Ah6 also quit at that time.

Kurt restored power mid-morning Sept 28 and we assessed damage to the main tower.  Our best guess is that the lightning struck near the base trailer and a current surge flowed down the power cable to DSM M21, trashing the charge controller, the PC104 stack, and the power interface panel.  Many of the sensors associated with M21 were found inoperative, but M21 appears to have acted as an expensive 'fuse', limiting damage to M22 and its associated sensors.  Gordon wrote:

"The most 'striking' damage was in the battery box at the main NCAR tower, the power interface panel on the lower DSM at the tower, and to systems at the OSU tower.  In general, the sensors and DSM higher on the main NCAR tower suffered less damage.

"The breaker in the conference center for power to the trailer was tripped, as was the breaker in the trailer which (I believe) is the circuit for power to the transformers at 'C' and 'M'.  The breaker that was tripped in the trailer is the lowest one on the panel, and is labelled 'class'  Kurt saw burn marks on one lug of a power cable connector at the trailer. I believe he said it was the socket at the end of the power cable from the conference center.

"All sensors except for one at the C site are reporting.  Sodars are OK, I hear.  The Picarro was not connected to AC.  It apparently suffered damage via the serial cable from the main tower DSM. So the damage was on the systems connected to the AC circuit to the main and OSU tower.  I think Tom and Kurt agree that it seems the lightning didn't strike either tower but the surge came in from the AC circuit.

"I like Kurt's suggestion that if a lightning storm threatens, that the power cables to the transformers be disconnected at the trailer. (Probabaly a good idea to throw the "class" breaker first).  That will shut down the Sodars and Piccarro. The ISFS systems and sensors at C and M should still run from their batteries.  I believe everything on the OSU tower is on battery?"

The sensor damage on the main tower was determined as in the following tables.  Sensors marked NG (Not Good) were removed and transported to Boulder.  We also found that one of the four sensors at each of the two soil sites were bad and brought down its mote if connected.  I recall that the soil temperature probe was bad at Grass, but the connector labels at Cactus were inadequate to determine the bad sensor (not the TP01 in my recollection).  The bad soil sensors were disconnected from the motes but not disinterred.

data_stats isfs_20120927_200000.dat.bz2 indicates that sensors at other sites quit reporting at 21:03:05, including two sensors at C: the 1.5m TRH and the barometer. The TRH resumed reporting on Sep 28 04:29 UTC.

Station 12 quit reporting at 21:03:05, but is now working after replacing the charging controller. However data from the TRHs at 12 via the bluetooth mote is not coming in.

0.5m TRH at Ah6 also stopped.

Other Damaged Equipment

• WIFI antenna (EantA) on main tower. Unknown status, probably dead.
• WIFI antenna (EantD) on OSU tower. Unknown status.
• USB disk drive (pocketec) on M21 DSM is not recognized by host systems. This contained 21 hours of data for Sep 27, but we have the same data that was received in real-time over the network.
• 5-port network switch in M21 is toast

Pocketec USB disk drive in Mu22, upper DSM on NCAR tower, is OK.
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