ME1/1 HIGH VOLTAGE SYSTEM
1.
HV SYSTEM OVERVIEW  BASELINE
The ME1/1 high voltage (HV) system is intended to provide the necessary supply voltage for all
Cathode Strip Chambers (CSCs) of the ME1/1 first forward muon stations.
The structure of the HV system is defined by the number and design of the ME1/1 CSCs. There
are 36 CSCs in each endcap station (Fig. 1) separated in two overlapped rings of 18 CSCs – Forward
(F) and Backward (B). The first ones have even numbers (ME1/1/1, ME1/1/3,…, ME1/1/35) while the
others –odd (ME1/1/2, ME1/1/4,…, ME1/1/36). Each CSC has six layers. All strip cathodes are cut
into two radial segments M1/1a and ME1/1b.
Each CSC layer has individual HV supply channel. Thus, the total number of HV channels for
one endcap ME1/1 station is 216, i.e. 432 channels for all system. Operational HV value is about
3.0 kV. A current per layer is up to 200 A at the particle background rate of 5 kHz/cm2 and gas
amplification of 105. Maximal output current should not exceed: 200 A in the separate channel, 43.2
mA per EndCap and 86.2 мА in the whole system.
Nominal gas mixture is Ar/CO2/CF4
(60%/30%/10%).
The structure of the ME1/1 HV system is based on CAEN SY1527 power supply system. Eight
28-channel A1733B modules are accommodated in one 19” «Euro-mechanics» crate. Each crate
provides computer control and settings of each HV channel.
Two HV crates are needed for ME1/1. These 2 crates are disposed in standard rack S1G10 located in
the control room USC55 ( fig. 2 ) . The total main power consumption per crate is estimated of about
3320 VA for whole ME 1/1 HV power supply system.
CERN standard high voltage cable and connectors are used. KERPEN HV cable has red colour,
diameter of 11 mm and 25 wires. Total length is about 110 m from HV crate to the chambers. 22 pins
HV REDEL KLG.H22.LLZG connectors are male, while KAG.H22.LLZBG – female. Two endcap
HV patch-panels, “HV pp ME1/1 near” and “HV pp ME1/1 far” (with 9 cables each) are located on
“near” and “far” sides of each YE1 disk. To minimise occupancy of the ME1/1 patch panel on the YN
nose, the high voltage distributor is used for two chambers Backward and Forward. The HV filter is
mounted on each chamber and connected to HV distributor.
ME1/1 High Voltage System
ME1/1b
ME1/1a
F – Forward CSC (even)
B – Backward CSC (odd)
Fig. 1: General view of the ME1/1 muon station
2
ME1/1 High Voltage System
Fig. 2. ME1/1 S1G10 HV rack position in the USC55 hall. Main parameters, composition and module arrangement.
3
ME1/1 High Voltage System
2.
HIGH VOLTAGE POWER SUPPLY
2.1. CAEN SY 1527 general futures

Houses up to 16 boards (HV/LV or "branch controllers")

Ad-hoc boards and peripheral systems

Communications via HS CAENET, CERN-approved field buses and TCP/IP

OPC Server to ease integration in DCS

Programmable handling of parameters and errors

Fast, accurate setting and monitoring of channel parameters

Multilevel management of user profiles

Live insertion of boards

Advanced trip handling

Hardware current protection

Modular and expandable power supply

Secure access to the system via Intranet

Remote debugging and technical support

Easy firmware upgrading
SY 1527 mainframe specifications: general
Packaging
Weight
Power requirements
4
«Euro-mechanics» rack, 8U- high, 19’’- wide,
depth 720 mm.
mainframe - 24 kG
module A1532 – 3.5 kG
Voltage range: ~100/230Vac
Frequency: 50/60 Hz
Power
3000 W
Max output power
2250 W
Maximal number of boards per crate
16
Operating temperature
From 0C to + 40C
Storage temperature
From -20C to + 50C
ME1/1 High Voltage System
Module A1733B technical parameters:

28 HV channels

Dual range 4/3 kV output voltage

2/3 mA current full scale

Available with positive or negative polarity

0.25 V Voltage Set / Monitor resolution

200 nA Current Set / Monitor resolution

Voltage ripple smaller than 50 mV pp

Programmable TRIP parameter

1÷500 Volt /sec programmable Ramp Up/Down

Current generator operation in Overcurrent condition
2.2.Channel technical parameters:
 Output voltage range
0-4000 V
 Nominal voltage 3000 V
 Output polarity
positive
 Voltage set resolution
250 mV
 Voltage monitor resolution:
250 мВ
 Voltage monitor precision
0.3%
 Ramp down
30- 300 V/s
 Ramp up 30- 300 V/s
 Output current range
0-0.2 mA
 Current monitor resolution
+/- 1 A
 Current monitor precision
<2%
 Temperature stability
<100 ppm/0C
 Long term stability
< 0.1%
5
ME1/1 High Voltage System
Fig.3 . Mainframe SY 1527 (left) and и HV module A1733B .
2.3. ME1/1 S1G10 HV Rack
Common view of S1G10 is shown on fig. 4.
Rack is housed two CAEN crates and rack patch panel.
Rack patch panel serves as interface between 16 x 28 –channel output of SY1527 mainframe and
18 x 12 -channel cables which runs to the four disc patch panels. Schematic is shown in Appendix A.
Rack grounding requirements Each rack must be connected to the hall ground line with a proper
wire. The maximum rack power consumption is not more than 3 kW. So grounding wire (copper braid)
cross section is 10 mm2 . Rack has special Rack Ground Terminal (RGT) to accept the crate grounding
wires and the rack grounding wire. Each crate is connected to the RGT with a proper wire. Each crate
has Crate Ground Terminal (CGT) at the back side of its chassis. Implementation of this circuits are
presented below.
2.4. Safety:
The following protections are provided by high voltage power supply system:

protection to prevent current and voltage overflow;

emergency shut-off by external signal;

emergency shut-off in case of disconnection of any high voltage connector by means of
INTERLOCK line break;

6
cable screens are grounded.
ME1/1 High Voltage System
a)
b)
c)
d)
e)
Fig. 4. ME1/1 S1G10 HV rack .
a) - front view, b) - rear view, c) - rack patch panel, d)-e) Left and right sides of the rack
grounding bar.
7
ME1/1 High Voltage System
2.5. HV CSC filter
The CSC filter box is located on each chamber. The electrical scheme of the filter box is given in
Fig.5. Resistor R1 is Multicomp with nominal value of 220 kOhm, 1 W. Resistor R2 is Multicomp
with nominal value of 2 kOhm, 0.25 W. Capacitor C1 is Hirono/Murata 2x2200 pF/6kV. Requirements
for HV test is that current leakage less then 10 nA at 4.5 kV during 1 hour test at T=20 – 25 oC and
humidity <70-90%.
Common GND
HV channel 1
R2
R1
C1
CSC layer 1(a)
(b)
HV channel 2
CSC layer 2 (a)
(b)
HV channel 3
CSC layer 3 (a)
(b)
HV channel 4
CSC layer 4 (a)
(b)
HV channel 5
CSC layer 5 (a)
(b)
HV channel 6
CSC layer 6 (a)
(b)
Screen
CSC GND
Fig. 5. Electrical scheme of the HV CSC filter.
8
ME1/1 High Voltage System
3.
HIGH VOLTAGE DISTRIBUTION SCHEME
A part of the ME1/1 HV system (for 2 CSCs) is shown in Fig. 6-7. HV supply cable consist of
three segments :

fist - between rack and disc patch panel (61-91m)

second connected the disc patch panel and the HV distribution box which was settled on
disc ( 15.5-32m)

third – in the output of the HV distribution box cable is separated in to two lines which
supplies pair of CSCs (backward and forward) ( 2- 2.5m).
Total length of cable can vary from 78.5m up to 128.5 m depending on chamber position.
Each HV module has one output connector: 22-pin REDEL (KLG.H22.LLZG type). Each
module is supplying one pair of CSCs (one Backward and one Forward – see Fig. 2). Except the 12
HV lines, there are 4 ground lines and 2 interlock lines. The cable screen is grounded.
The output of the HV module is connected to the HV Distributor box through a 22-line cable and
YE1 HV patch panel. The Distributor is mounted on the HE patch panel. There are three 22-pin
connectors on this Distributor. The first one, receives all HV module output lines. Other connectors is
directly coupled through a 2.5-m and 2.0-m long HV cable to the filter box of the Forward and
Backward CSCs respectively.
Picture 7 illustrates schematic of ME1/1 interlock and chambers grounding. Pair of neighboring
supplied from single cable chambers are connected in sequence by INTERLOCK signal. So breaking
any of four connectors in the chain should results in HV channels power-down.
High voltage cables routing scheme in radial trays of the YE+1 disk is presented on Picture 8.
9
ME1/1 High Voltage System
Fig.6. ME1/1 HV supply cable.
Fig.7. Schematic of ME1/1 interlock and chambers grounding.
10
ME1/1 High Voltage System
Fig. 8. High voltage cables routing scheme in radial trays of the YE+1 disk.
11
Appendix A.I
Schematic of the S1G10 rack patch panel. Page 1 of 2
ME1/1 High Voltage System
Appendix A.II
Schematic of the rack S1G10 patch panel. Page 1 of 2.
13
ME1/1 High Voltage System
Appendix B.I
ME1/1 HV cable.
14
ME1/1 High Voltage System
Appendix B.II
ME1/1 HV cable.
15
ME1/1 High Voltage System
Appendix B.III
ME1/1 HV cable.
16
ME1/1 High Voltage System
Appendix C
ME1/1 HV rack S1G10.
17