Transcript Recent cross-wiring issue and implication for circuits protection

Upgrades and Activities of 13kA EE
systems during LS1
Bozhidar Panev TE-MPE-EE 23.11.2012
Installation of Snubber capacitors in RQD/F EE systems
• The benefit: To suppress the voltage transient perturbations in the
circuits during switch commutation and to make the opening process
lighter by reducing the electrical arc existence
• All 16 EE systems of RQD/F circuits will be equipped. Four snubber
capacitors per system + associated auxiliary boards  in total 64
snubbers and 64 boards
• All parts and components have been manufactured, commissioned,
packed and prepared to be transported to each UA area. Transport will
be required
2
Installation of Snubber capacitors in RQD/F EE systems
• Difficulties during the installation:
Snubber Capacitors - RQF
 Limited space inside the switch
acoustic shield housing
 The installation of snubbers on
the upper stage requires to lift
and handle heavy stuff at 2m
height over the ground.
Snubber Capacitors - RQD
2.0m
• The last issue has been discussed with S. Pelletier from transport
service in the presence of a safety person. The accepted solution is to
use a lifting mechanism, fixed at the ceiling inside of the switch housing.
• The IHEP team (4 experienced persons) is scheduled to perform the
work. All of them have previously participated in the EE systems
maintenance and the RB snubbers installation
• The work is planed to start in May 2013. The time estimation is 3 days
per one UA area  24 days in total
3
New arc chambers for RQD/F EE switches
• It will be combined with snubber capacitors installation. Two sectors
(S12 and S23) are already equipped. Still 12 EE systems  96 arc
chambers have to be replaced.
• The currently installed arc chambers  up to 200V arc feeding voltage
(design specification and hard limit)
• The new arc chambers:
 Identical design as in the dipole EE
systems
 Good performance up to 1050V (arc
feeding voltage) is guaranteed
 All chambers have been delivered to
CERN earlier this year
• The activity does not require the transport service
4
Mechanical modification in all RB dump resistors (DQRB)
• To prevent the potential damage of
the DQRBs in case of double
amount of energy deposited in the
dump resistors
thermal
expansion
crack and short
• Difficulties  mainly due to lack of
space at the end of some DQRBs
 e.g. in P1, P3 and P5 the “Roman
pots” or beam pipe supports are
placed between dump resistors
Modification
• The transport service will be involved to
move temporarily some dump resistors
in order to gain enough space
•
•
•
•
53 dump resistors (16 RB EE systems + spares) will be modified.
The estimated time  3 DQRBs per day  ~ 20 days totally
The activity is scheduled to start in July 2013.
The IHEP team + AGH team (3 persons) will perform the work.
5
RB Dump resistors – thermostat replacement
• The installation of new thermostat is not fully completed
 Two dump resistors: one in RR73 and one in RR77 still need to
be equipped
• Difficulty:
 Resistors are blocked by concrete shield and there is little
access for manipulation
• During next TS both two
places will be visited and
carefully observed
• The activity is planed to
start in Aug 2013. Expected
duration: One week
• IHEP team + AGH team will
be involved
6
Power switching relay (230V/8V) of holding coil
(RL4,6,8,10 in BCMs)
• A recent inspection has found the significant erosion of contacts due
to electrical arc. The risk to burn the holding coil increases.
• In the beginning of closing process I = 22A(230V) then switched to
0.5A(8V)
• As a part of preventive maintenance it has been decided to replace
these relays in all EE systems (RB and RQD/F)
• 8 relays per EE system  32 systems  256 relays in total
• The new selected relay (still under
consideration):
 Better contact material - AgSnO2
instead of AgCdO
 Maximum peak current - (4 times
higher)
• TE-MPE-EE staff will perform the
activity.
7
Dump resistors re-configuration
• The expected new conditions in
LHC after LS1 require a new
configuration of the dump
resistors in RB and RQD/F EE
systems
• RB_EE system  requires only
cable reconnection to get all
three resistors in parallel
Now
After LS1
I
I
R
Requiv. » 138mW
t » 55s
R
R
R
R
R
Requiv. » 70mW
t » 102 s
• RQD/F_EE system  dump resistor internal modification
- Curren situation: R = 7.7 + 4*5.0 + 1.2 = 28.9 mΩ (51 MQ / circuit)
R = 6.6 + 4*5.0 + 1.2 = 27.8 mΩ (47 MQ / circuit)
- After LS1: R = 7.7 + 2*5.0 + 1.2 = 18.9 mΩ (51 MQ / circuit)
R = 6.6 + 2*5.0 + 1.2 = 17.8 mΩ (47 MQ / circuit)
t » 9.8s
t » 9.4s
t » 15.1s
t » 14.77s
• The activity is planed to start in Sep. and will take 2 weeks
• The work will be executed by IHEP team + AGH team + TE-MPE-EE
8
RB Dump resistor – 4 water cooling stations relocation
in P1 and P5
• The reason: Installation of new collimators in the place which, currently
occupied by water cooling station
• Cooling stations together with adjacent electrical cupboards will be
moved on top of one of the RB-dump resistors. Such a installation has
already been done in P3
• EN-CV and EN-EL will be involved
• The activity is scheduled to start  in Aug. and it will take 2 weeks.
• The participants  AGH team (3 persons) + TE-MPE-EE
9
Water cooled cable exchange of some 13kA EE systems
• Cracks in the rubber of the water cooled cables have been observed
close to the connection point with “busway”
• All cables susceptible of containing such a cracks will be replaced:
 P4 right  RB, RQD/F
 P6 left & right  RB, RQD/F
 P8 left and right  RB, RQD/F
• The work will be performed by EN-EL.
• The presence of a EE specialist is
needed during establishing the
connection with the switch “busway”
• The voltage drop measured across the
connection point must determine the
resistance of  ≈ 0.6 μΩ
Modification in SUM_Fault electronic board
•
•
•
•
A few suspected diodes will be replaced
The signal “ST_OPENFAIL” will be removed by hardware modification
32 PCBs will be modified  1 per EE system
TE-MPE-EE staff will perform the work.
10
General maintenance of all 13kA EE systems
• Micro-switches(S1/2/3/4) functional check
• Air gaps of the breakers (∆1 and ∆2)  measurement and adjustment
• Mechanical pressure verification of the main contacts  adjustment if
required
• Cleaning of the main and arcing contacts
• Time delay check (600ms and 340ms) only RB EE system
• Verification of all bolted electrical connection
• All 32 EE systems (RB and RQD/F)
• The activity is scheduled for Sep.-Oct. 2013 and it will take ~1.5 months
• The work will be performed by IHEP team + AGH team supervised by
TE-MPE-EE
11
Recourses and Conclusions
Activity
Snubbers RQD/F
DQRB mechanical
modification
Water cooling station
relocation
Time estimation
2 EE sys. / 3 days
Total
24 days
~ 2 weeks
Executors
IHEP team (4 persons)
IHEP team (4 persons)
AGH team (3 persons)
AGH team (3 persons)
TE-MPE-EE staff
IHEP team (4 persons)
AGH team (3 persons)
IHEP team (4 persons)
AGH team (3 persons)
TE-MPE-EE staff
3 DQRBs / 1 day
~ 20 days
1 station / 2 days
~ 2 weeks
2 weeks
TE-MPE-EE staff
2013
1 week
TE-MPE-EE staff
IHEP team (4 persons)
TE-MPE-EE staff
2013
Thermostats in P7
Dump resistors
reconfiguration
3 EE sys / 1 day
Power relay replacement
of the holding coil
3 EE sys / 1 day
SUM_FLT Electronic
board modification
General
maintenance
1 EE sys / 1.5 days
~ 1.5 months
May-June 2013
Jul-13
July-Aug. 2013
Aug-13
Sep-13
Sep.-Oct. 2013
• The main contract with IHEP is ready for approval but not yet signed
• As a back up solution  The AGH team can handle the work but some
training is needed in order to get more familiar with the EE systems. In
that scenario at least 30% more time must be added
• All technical details are determined and most of the equipment is already
available
• All issues are included in Katy’s general planning
• CERN supervision team is: Mathieu, Knud, Bozhidar
12
Thank You