Reports 1-1 of 1 Clear search Modify search
Environmental Monitoring (Environmental Monitoring)
fiori, schofield, tringali, dattilo, paoletti, d'andrea - 13:14 Monday 16 March 2026 (68882) Print this report
grounding injection test

Last Friday (13th March) we installed the ground current injection setup (pictures 1-6) and we tested it without ITF. Figure 7 shows a scheme. The injection is performed between the electrical ground of the NI SAT crate and the SR vacuum chamber. The driving signal was one 11Hz comb (saw-tooth by the Hameg generator) amplified to approx 0.5 A and 5 V  (as read in the display of the TIRA BAA-120W amplifier, and also with one ammeter in series with the resistor). Tips by Robert and Federico: do not exceed 1A, the resistor should not become "hot". Be careful not to swap '+' and '-'. The two ends of the cable out of the amplifier (both black) have been labelled. 

The current clamp sensor (ENV_CEB_GROUND_CURR_MON) is described in this entry: https://logbook.virgo-gw.eu/virgo/?r=68265. It was placed around the cable connecting the ground of all platform racks to the CEB hall main ground copper bar. In turn this copper bar is connected to the CEB main copper bar located in the service room next to the main entrance. Finally the latter bar is connected to the safaty earth, which consists of one external ring with ground rods placed all around CEB.

The comb is sensed widespread: by the current clamp (above) and by the ENV_CEB_ELECTRIC probe which is measuring the voltage difference between the WI SAT rack and the WI vacuum chamber.

Figure 8 shows the injection (purple). In the blue curve the current clamp was disconnected from the grounding cable.

   

Images attached to this report
Comments to this report:
Paoletti - 18:09 Monday 16 March 2026 (68886) Print this report

During the test injection, the sensor with the best Signal to Noise Ratio is ENV_CEB_ELECTRIC, followed by ENV_CEB_GROUND_CURR_MON and ENV_CEB_GROUND_MAG.

The magnetometers near the towers all detect the Comb signal, in some cases up to three orders of magnitude above the noise floor.

This is expected: the cable running from the TIRA BAA-120W power amplifier output toward the NI suspension rack and, in parallel, toward the SR tower forms a large loop, which generates a significant magnetic field.

This must be considered when evaluating the effect in Hrec: coupling may arise from the magnetic field rather than from currents in the grounding connections, as the field can act directly on the mirror magnets.

When only real ground-current flow is present, this effect should be absent or strongly suppressed, since no large loop is formed.

Images attached to this comment
Search Help
×

Warning

Error

The present report has been modified outside this window. Please check for its integrity in the main page.

Refreshing this page will move this report into drafts.

×