WHT primary mirror axial load cell test

During the aluminising of the WHT mirror, when the mirror is removed from the cell, there is an opportunity to test and adjust the radial load cells.

We need to connect the mains power to the mirror support controller. This can be done applying power to cable: 139TCC12 with the blue mains test cable from AF2, kept in the AF2 cupboard. Connect a DVM to the "Force" terminals of the Digital Mirror Support Controller (DMSC) card. This is the output of the strain gauge amplifier of the mirror support system. (See for details the Technical Manual of the mirror support kept in the ops room) Now take a reading of the DVM with no force applied to the radial load cells. Then repeat this with a know weight holding steady on top of each radial load cell. The weight I used was 6.35 kg. Results of test carried out on 8th of Feb. 2012:

Load-cell Zero force (V) 6.35kg force (V) mV/kg
North (0 deg.) 0.251 2.923 421
S/E (120 deg.) 0.374 3.061 423
S/W (240 deg.) -0.096 2.569 420

 


This file: http://www.ing.iac.es/~ops/private/operations/WHT primary mirror axial load cell test.htm
Jürg Rey, 10 February, 2012