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.  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 current flowed down the power cable to DSM M21, totally trashing the charge controller and the PC104 stack.  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 Piccarro 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 follows: