Grounding of detectors and their electronics
Grounding of detectors and their associated electronics is a complicated and
delicate problem in large experiments. The general aim in grounding is to
prevent the pick up of noise in sensitive signal connections. Ground loops
can potentially between sub-systems can generate parasitic currents which
can seriously degrade the correct capture of small signal levels from the detectors. The
communication between different parts of the system can also be seriously affected by the
build up of common mode voltage difference ( for copper links). In some cases safety regulations for the use of power
supplies (especially high voltage) can impose rules that makes it impossible to design the
perfect grounding scheme.
Grounding, Shielding and Power Distribution in LHCb
EDMS 473833, Grounding
network in LHCb.
EDMS 478224, Electrical
distribution network for the LHCb experiment.
EDMS 473770, Mains power
requirements for the LHCb experiment.
Links to drawings:
Grounding in the counting house
Grounding of equipment
Grounding of the rails
General points to be aware of:
- All structures must be connected to safety ground.
- Prevent ground loops via sensitive signal paths
- Use galvanic isolated links when ever possible.
- Use differential electrical links (if optical not possible) and insure
sufficient common mode range to reject noise and ground potential
- Use shielded cables when ever possible.
- Take special care of high voltage and its distribution.
- No single point failure must generate safety hazards ( e.g. high voltage
connected to accessible structure).
- Use floating low voltage power supplies.
- Be aware the ECS interfaces based on I2C or
JTAG can introduce ground loops as these signals are single ended.
- Linear voltage regulators does NOT give galvanic
- Distribution of power from large bulk power supplies
(e.g. Wiener Maraton) will give specific grounding problems.
- TO BE EXPANDED
F. Szonsco from CERN has
made a web page on EMC
gives a course on EMC problems.
His lectures are available directly on the web.
CMS EMC web
Alice has a preliminary grounding policy
This page was last modified by JC on
16 May, 2006. This page has been accessed
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