Date: Thu, 9 Nov 2000 10:52:31 +0100 From: Dieter Eversheim To: Gerhard Mallot , Igor Konorov , Jens Bisplinghoff , Ralf Ziegler Subject: Earthing and Grounding Parts/attachments: 1 Shown 60 lines Unknown text 2 209 KB Image ---------------------------------------- [The following text is in the "Windows-1252" character set] [Your display is set for the "US-ASCII" character set] [Some characters may be displayed incorrectly] The Situation There are two grounds available, the ground for supports, structures, machines and motors,....named "Structure Ground" and the "Electronics Ground" (yellow/green flexible cable) for front-end electronics, high voltage supplies and detector control via computers,.... In general all 230 Volt AC outlets in the containers and on the shielding wall to power the electronic racks, computers and detectors are on Electronics Ground. The same is true for the power outlets of the Uninterruptable Power Supply (UPS). Exceptions are the power for heaters, refrigerators, motors, pumps, light from the ceiling,..., which are connected to Structure Ground. The 3-phase outlets can be configured for Electronics Ground on demand. There will be ground rails in the experiment area for Electronics Ground, which has been installed already (at chest hight), and distinguishable from this position the Structure Ground. Consequences With the measures from above, three scenarios can be realized (cf. the figure in the attachment). - The normal scenario 1) should be followed whenever possible (SciFis, calorimeters, µ-walls,. . .), since interference with other components is expected to be minimal in this configuration. - Scenario 2) is a special exception for the RICHs, since the HV-ground return can not be separated from the supports and structures of the RICHs. Then, with short HV-cables, the front-end electronics at the detector housing, and the data transmission to the data acquisition via optical links, interference with and from other detector components is also kept minimal. - The second exception is related to the polarized target (scenario 3)). All high power consuming equipment and its local control is connected to Structure Ground, as usual. Since only a few data have to be exchanged with the experiment control, all data lines in question have to be galvanically isolated from the Electronics Ground. Open Questions - Since all ROBs are linked to the experiment electronics via optical fibers, they can be connected to Structure Ground unless UPS is used. - Will the beam-momentum station follow scenario 1) or scenario 3) ? Rules - Prepare for each detector a grounding schematic or a scheme. - Use for connection to Electronics Ground only braids (or cable) that is covered with an isolation, to avoid any accidental shorts with the Structure Ground (via rails, supports,... as happend pretty often in the past set-up already ). - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Dieter Eversheim Bonn University Institut fuer Strahlen- und Kernphysik Nussallee 14-16 D-53115 Bonn Tel.: ++49-228-73-5299 FAX: -2505 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - [Part 2, Image/JPEG 209KB]