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Modification of dump resistors for dipoles, DQRMB. Aim of modification Way of modification Advantage of modification. Marek Ciechanowski AGH, Poland. Aim of modification. Two banks of resistors, 3 resistors in each bank connected in parallel
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Modification of dump resistors for dipoles, DQRMB • Aim of modification • Way of modification • Advantage of modification Marek Ciechanowski AGH, Poland
Aim of modification • Two banks of resistors, 3 resistors in each bank connected in parallel • 78 horizontal plates connected in series form one resistor which gives 225 mΩ of resistance • When switch on the one side will not commute, only one bank of resistor must absorb the all energy of the dipoles (1.3 GJ ) • temperature of one resistor may increase up to 466oC (over 150o nominal) • overheating of resistor will cause the thermal expansion (α = 12·10-6/K) of the plates up to 40mm • The plates will push the insulating board which separate the resistor plates from the bus bar connection • breakage the insulating plate and direct contact between bus bars and resistor plates • damage of the resistor
Sometimes access to the resistor was easy, sometimes not Modification are done in all dump resistors in the LHC tunnel and in 3 spare resistors in the Bldg 388 also.
Advantages • Increase free space between locking washer and insulation plate • Eliminate sharp edge of fixing screw • Decrease the risk of damage the resistor in a case of switch fault
Connectors and sockets check Marek CiechanowskiAGH, Poland
During maintenance two possible fault sources were found • Not tightened screws in electronic cabinets and racks • Broken or bad fixed pins in connector or socket
Results of check • The ~2250 cables and corresponding sockets were checked • It gives near 51 000 pins checked • 67cables/socket with errors/problems were found • inspection is documented in MS excel file • Each xls worksheet contains data for one alcove/system • The most errorshavebeenfound in UA63 and UA67