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 40 mm

• 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

Way of modification

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 Ciechanowski AGH, 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

Broken cable insulation

Results of checkCable number

equipment id socket id

number of pins

conector type

observation status

number of pins

socket type

observation status

DQPIB

R34 SK51 48F ok 48M ok SK52 48M ok 48F ok

1306110 SK53 18M ok 18F ok1306111 SK54 12M ok 12F ok1306112 SK55 18M ok 18F ok1306113 SK56 12M ok 12F ok1306118 SK41 28M ok 28F ok

from BOX SK42 12Mpin nr 1 broken fixed 12F

pin nr 1 crushed fixed

SK61 48F ok 48M ok SK62 48M ok 48F ok

1306114 SK63 18M ok 18F okfrom BOX SK64 18M ok 18F ok

1306116 SK65 18M ok 18F ok1306117 SK66 18M ok 18F ok

SK70 12F ok 12M ok1308910box 12M ok 12F ok1306115box 18M ok 18F ok

DQPIB

R37 SK51 48F ok 48M ok SK52 48M ok 48F ok

1306096 SK53 18M ok 18F ok

1306097 SK54 12M

unscrew (loose) connector fixed 12F ok

1306098 SK55 18M ok 18F ok1306099 SK56 12M ok 12F ok1305019 SK41 28M ok 28F ok

from BOX SK42 12Mpin nr 1 broken fixed 12F

pin nr 1 crushed fixed

SK61 48F ok 48M ok SK62 48M ok 48F ok

1306100 SK63 18M ok 18F ok SK64 18M ok 18F ok

1306102 SK65 18M ok 18F ok

• The ~2 250 cables and corresponding sockets were checked

• It gives near 51 000 pins checked

• 67 cables/socket with errors/problems were found

• inspection is documented in MS excel file

• Each xls worksheet contains data for one alcove/system

• The most errors have been found in UA63 and UA67