Procedures for Wiener/CAEN power supplies and crates
17th March 2010
Link to Crate/Power Supply Database
CERN Contracts for 2010. Use these codes when purchasing/repairing equipment via EDH:
All enquiries should be sent to firstname.lastname@example.org
Procedures can be found at the following web addresses. These include all information on repairs, purchases etc.
For repairs, Laurent Roy can organise transport to the Electronics Pool office.
PLEASE NOTE that the SUB-DETECTOR CONTACT PERSON must fill in the Fault Report.
Power supplies: general information
Power supplies for sensitive analog front-end electronics is a delicate point that requires significant attention in large scale systems. Power supplies must be used in a fashion compatible to the defined grounding scheme. Analog front-end electronics is in many cases extremely sensitive to noise in the power supply because of the single ended nature of detector signals. It is in most cases required to have separate power supplies for analog and digital front-end electronics to prevent noise from digital circuitry to disturb the analog part.
The question of location of the power supply units and the related transfer of power on cables often have significant problems. Low frequency voltage drops on cables can to a large degree be compensated for by the use of remote sensing to compensate for cable losses. Remote sense can on the other hand also pose stability problems as the compensation loop must be stable under large load variations and with different cable characteristics. In special cases the remote sense circuit must be specially adapted to the final working conditions. High frequency components can only be handled with the use of local decoupling capacitors.
In most cases a difficult choice must be made between using normal commercial power supplies in the counting room with long cables (~80m) to the front-end electronics in the detector, or having power supplies in the cavern close to the experiment but then having to deal with radiation and magnetic fields. Power supplies for the use in the cavern must be specially designed to handle the radiation effects and the magnetic fields. For the general LHC experiments only few companies are being considered to be capable of supplying power supplies that can handle the environments of the experimental caverns. The CERN ESS group is involved in the qualification of power supplies for the use in the experimental caverns and their purchase via CERN frame contracts.
The power dissipation in power supply cables in the experimental cavern must also be carefully considered as there is only a limited air condition capability in the cavern (already marginal).
Wiener Maraton power
supplies for use in radiation and magnetic fields
Electronics meeting dedicated to power supplies in November 2003 LHCb week.
Measurements of the electronic crates for LHC experiments. Report. K. Kahle, A. Funken. 18-11-2003:
General points to be aware of:
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