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					CERN
CH-1211 Geneva 23
Switzerland                                             CERN Div./Group or Supplier/Contractor Document No.

                                                                  LHC-MTA-TF/AS/rl
               the                                                     EDMS Document No.
               Large                                            342797 rev. 0.1-draft
               Hadron
               Collider
               project
                                                                                         Date: 2002/04/22




                              Technical Manual
                                     and
                               Test Procedure


                      THE DIQH TEST SYSTEM

                                               Abstract
The DIQH tester type HCDQHDS001 is intended for the following application:
     To test the quench heaters of the pre-series superconducting magnets assembled in
        industry
     To validate the integrity of the quench heater circuits
The DIQH tester contains: 1) a Macintosh PC instrumented with a National Instruments
acquisition card and a dedicated LabView program, 2) a National Instruments connection board
for input signals linked to the acquisition card, 3) a trigger box generating 6-0V trigger signal on
acquisition card and 12-0V on the quench heater power supply, 4) a quench heater power supply
containing the capacitor bank.

The DIQH test system is a Low Voltage B device and therefore stringent safety precautions are
prevailing.

        Prepared by :                  To be checked by :                     To be approved by :


     M. Chamiot-Clerc                     K-H. Mess                              A. Siemko
        M. Gateau                       CERN/LHC-ICP                           CERN/LHC-MTA
        R. Mompo
     CERN/LHC-MTA                       S. Russenchuck                            F. Szoncso
                                        CERN/LHC-ICP                             CERN/TIS-GS
     C. Charrondière
      B. Khomenko                        D. Tommasini                            J. Vlogaert
       H. Reymond                       CERN/LHC-MMS                           CERN/LHC-MMS
        A. Rijllart
     CERN/LHC-IAS

                                   Distribution List :
 M. Chamiot-Clerc, C. Charrondière, M. Gateau, B. Khomenko, K-H. Mess, R. Mompo,
 H. Reymond, A. Rijllart, S. Russenchuck, A. Siemko, F. Szoncso, D. Tommasini,
 J. Vlogaert.
                                                                    EDMS No.
                                                         342797 rev. 0.1-draft
                                                                                     Page 2 of 11




                                History of Changes

Rev. No.      Date       Pages                       Description of Changes


0.1-draft   2002-04-22    All       Document created by M. Gateau. To be checked and
                                    approved (see distribution list). Deadline: 26 April 2002.
                                                                                  EDMS No.
                                                                      342797 rev. 0.1-draft
                                                                                                   Page 3 of 11



                                         Table of Contents
1.    INTRODUCTION .......................................................................................4
2.    SAFETY PRECAUTIONS ............................................................................4
2.1    GENERAL ................................................................................................ 4
2.2    SAFETY INSTRUCTIONS ............................................................................ 4
3.    HARDWARE .............................................................................................5
3.1    EQUIPMENT ............................................................................................ 5
3.2    CABLING ................................................................................................ 5
3.3    CAPACITOR BANK CHARGE AND DISCHARGE .............................................. 6
4.    SOFTWARE USE .......................................................................................6
5.    OPERATION PROCEDURE .........................................................................7
5.1    TO CONNECT QUENCH HEATER TO THE POWER OUTPUT .............................. 7
5.2    FOR 715J ENERGY.................................................................................... 7
5.3    FOR MAXIMUM ENERGY (2550J) ................................................................ 7
5.4    TO DISCONNECT QUENCH HEATER FROM POWER OUTPUT............................ 7
6.  TECHNICAL DESCRIPTION .......................................................................7
6.1  GENERAL DESCRIPTION ........................................................................... 7
6.2  ENVIRONMENTAL CONDITIONS ................................................................. 8
6.3  MAIN PARAMETERS .................................................................................. 8
6.4  CAPACITOR BANK .................................................................................... 8
6.5  TRIGGER CIRCUIT ................................................................................... 9
6.6  CHARGE DETECTOR ................................................................................. 9
6.7  CHARGE MONITOR ................................................................................... 9
6.8  CURRENT MONITOR ............................................................................... 10
6.9  SOFT START CIRCUIT ............................................................................. 10
6.10 INTERNAL POWER SUPPLIES ................................................................... 10
6.11 CONNECTION TO EARTH ......................................................................... 10
7.    DIAGRAM ..............................................................................................11
                                                                       EDMS No.
                                                             342797 rev. 0.1-draft
                                                                                      Page 4 of 11




1. INTRODUCTION
The Dipole Industry Quench Heaters (DIQH) test system has been prepared to verify the
proper functioning of quench heaters on pre-series magnets assembled and instrumented with
quench heaters in industry. To perform this test an energy from a capacitor bank is dissipated
in each quench heater of the magnet at ambient temperature. Safety precautions have been
undertaken due to the high energy that would be dangerous for persons. The capacitor bank
(7.05mF) is discharged in one quench heater at a time. Firstly 715J (450V) is applied, secondly
the nominal value of 2550J (850V) is dissipated. The applied voltage and current are recorded
on a labview program. Discharge validity can be evaluated from automatic calculations
displayed. The 8 quench heaters of a magnet shall be verified following this procedure.


2. SAFETY PRECAUTIONS

  2.1 GENERAL
The quench heater power supply is a high energy capacitor bank. It has been designed in such
a way that the personal safety shall never be violated. The crate containing the capacitors will
never have to be opened which would leave un-accessible the parts under voltage or current
carrying conductors under operating conditions.

  2.2 SAFETY INSTRUCTIONS
This instruction is dedicated to people with a suitable technical training and education, familiar
with electrical risks and who can keep the risk for themselves and for others as low as
possible. Only authorised personnel shall be allowed to operate the DIQH test system.

Before operating the quench heater power supply make sure you have read and understood
the operating instructions. Ensure that you observe all the hints and warnings contained within
it. If not following the operation instructions, you contravene the safety regulations for
operating the DIQH test system.

Before operating the quench heater power supply check for any obvious signs of physical
damage that may occur during transportation and installation. In case of doubt report
immediately to the designers of the quench heater power supplies in CERN/LHC/ICP group.
The quench heater power supply must be powered with 230VAC referenced to earth.

It is forbidden to disconnect mains cable during whole operation of the apparatus.

All cabling connections must be done before powering any hardware equipment.

It is forbidden to disconnect any of the connectors under a capacitor bank charge voltage
exceeding 50V.

The quench heater power supply may only be operated in a clean and dry environment. Ensure
that no objects or liquids can get into the crate through the ventilation grids. The quench
heater power supply shall not be operated in the vicinity of flammable gases or fumes.

The quench heater power supply is air cooled by convection. Therefore, ensure that the
ventilation grills are not obstructed and that airflow is available.

Once a series of tests is terminated, check the voltage that shall be less than 50V on the
labview display. If higher voltage is observed, reset and trigger immediately the power supply
again to keep the voltage below 50V. Then switch the power OFF by using the main switch.
                                                                    EDMS No.
                                                         342797 rev. 0.1-draft
                                                                                        Page 5 of 11


Never leave the quench heater power supply under power and unused for prolonged duration,
i.e. during night or without direct supervision. Capacitor bank shall be discharged for
transportation and stand by.

For troubleshooting consult directly quench heater power supplies designers in CERN/LHC/ICP
group.


3. HARDWARE

  3.1 EQUIPMENT
The DIQH system is composed of:
    One Macintosh PC instrumented with a National Instruments acquisition card and
      labview program
    One National Instruments connection board for input signals linked to the acquisition
      card
    One trigger box that generates 6-0V trigger signal on acquisition card and 12-0V on the
      quench heater power supply
    One quench heater power supply containing the capacitor bank; power output (Socapex
      connector) is to be connected to the quench heater strips on sockets

  3.2 CABLING
All interconnections shall be done before switching on any instrument.




                                                           Quench heater power supply



                                                         Trigger
                                                                          Monitor

                                                                   Courant
    Macintosh with
   labview program



                                                                               Power output to
                                                                               quench heater


                                                                                    Socket

                             Connection
                               board                        Trigger box



Connection board     Wire       Socket
Monitor               3           33
                      4         66, 67
Courant               1           65
                      2           31
Trigger              White        28
                     Blue         61
                                                                       EDMS No.
                                                             342797 rev. 0.1-draft
                                                                                      Page 6 of 11

  3.3 CAPACITOR BANK CHARGE AND DISCHARGE
Once all equipment has been switched ON and connected properly, especially power output
connected to quench heater, reset the quench heater power supply with its front panel
button to allow the charge of the capacitor bank. To discharge it into the quench heater, press
the button on the trigger box that will send the trigger signal.


4. SOFTWARE USE

The labview program will be launched automatically when the Macintosh is switched on.

                     By pressing this button, the user has access to the online values of voltage,
  View Online        current, and trigger level. Voltage charge must be controlled from this
                     window.

             From this button the user has access to the next window from where the
   ON
             configuration file for DIQH can be loaded (use default configuration).

Then press            to arm the system that is now waiting for a trigger signal from the trigger
               RUN
box.

Once a trigger is received, the measurement file can be saved under a chosen directory and
name. Voltage and current discharge are displayed on the graphs. Automatic calculation of
discharge parameters can be visualized by pressing on   QH TEST    . The next window is
then displayed.




A particular attention should be taken on initial resistance (~20), time constant (~140ms)
and its derivative (-1<’<1), energy (~2550J for 850V, ~715J for 450V), and on minimum
reached voltage at the end of discharge (Vmin<10V).
                                                                     EDMS No.
                                                           342797 rev. 0.1-draft
                                                                                    Page 7 of 11

Previously stored data can be visualised and saved with comments by pressing on

             View           AND         Rec Info
          stored data



5. OPERATION PROCEDURE
The 8 quench heater strips of the magnet should be tested one by one in the following way.

  5.1 TO CONNECT QUENCH HEATER TO THE POWER OUTPUT
      The quench heater power supply must show trigger signal on the front panel (trigger
       led indicator flashing red)
      Displayed voltage on labview window must be lower than 50V
      Check whether the SOCAPEX connector is disconnected from the quench heater power
       supply crate
      Connect the quench heater leads to the sockets
      Reconnect the SOCAPEX connector on the quench heater power supply crate

  5.2 FOR 715J ENERGY
      Press reset button on the front panel of the quench heater power supply to charge
      Control the charge voltage on the labview window
      Once 450V is reached, arm the acquisition system
      Send a trigger signal from the trigger box by pressing the button on it
      Check the discharge parameters to validate the test result

  5.3 FOR MAXIMUM ENERGY (2550J)
      Press reset button on the front panel of the quench heater power supply to charge
      Control the charge voltage on the labview window
      Once 850V is reached, arm the acquisition system
      Send immediately a trigger signal from the trigger box by pressing the button on it
      Check the discharge parameters to validate the test result

  5.4 TO DISCONNECT QUENCH HEATER FROM POWER OUTPUT
      The quench heater power supply must show trigger signal on the front panel (trigger
       led indicator flashing red)
      Displayed voltage on labview window must be lower than 50V
      Disconnect the SOCAPEX connector from the quench heater power supply crate
      Disconnect the quench heater leads from the sockets


6. TECHNICAL DESCRIPTION

  6.1 GENERAL DESCRIPTION
This specification concerns the supply of the heater discharge power supplies for the LHC
superconducting magnet protection. In case of a magnet quench these power supplies will
energise the heater strips inside the magnet. By these means the propagation of the quench is
enhanced in order to prevent damage to the magnet coil. Each power supply contains a
capacitor bank with 6 Aluminium electrolytic capacitors (4.7mF/500V) resulting in a total
                                                                      EDMS No.
                                                            342797 rev. 0.1-draft
                                                                                     Page 8 of 11

capacitance 2x14.1mF/500V which is connected in series. The nominal operating voltage of the
capacitors will be Unom=450V giving a maximum stored energy of 2.86kJ.
According to LHC-PM-ES-0002.00 each magnet will experience approximately 10 quenches
after its installation in the LHC tunnel. In addition there will be approximately two test
discharges for diagnostic purposes per year (during LHC shutdown periods). The result is an
average of 50 discharges during 20 years of LHC operation. Probably most of the DQHDS
remain powered and charged during the shutdown periods, resulting in about 175000 hours of
operation within 20 years. This requires long life quality for all parts of the power supply and
an industrial grade manufacturing process.

  6.2 ENVIRONMENTAL CONDITIONS
The power supplies will rely on passive cooling and face the following atmospheric conditions
(see also LHC-PM-ES-0002.00 paragraph 6.6).
Temperature: 14°C - 26°C
Dew point: 12°C

  6.3 MAIN PARAMETERS
The general electric parameters of the power supply and the specification of all external
connectors are summarised in the following tables.

Mains power                 230V 50Hz redundant UPS
Power consumption           15W (35W peak), cos0.88
Nominal charging voltage    2x450V
Time constant               78ms
(discharge)
Charging time               25min
Stored energy               2.9kJ
Trigger (negative logic)    12V  0V
Fuses                       1A, 60mA
Temperature range           0°C - 70°C
Weight                      15kg


Name              Ratings            Type
Mains power       230V               FCI-Burndy UTG0187PVDEX
Trigger           12V/1A DC          FCI-Burndy UT00104S21T female
Charge detector   12V/1A DC          FCI-Burndy UT00104P21T male
Charge monitor    15V/0.1A DC
Quench heater     1kV/100A surge     Amphenol Socapex SL E F 22 B

The power supply follows a modular design and consists of six functional units.

  6.4 CAPACITOR BANK
Each power supply contains a capacitor bank with 2x3 Aluminium electrolytic capacitors
(4.7mF/500V) forming a total capacitance of 2x14.1mF/500V connected in series. The nominal
operating voltage of the capacitors will be Unom=450V giving a maximal stored energy of
2.86kJ. The individual capacitors are connected with the help of screwed copper busbars. The
centre tap of the capacitor bank is directly connected to the analog ground point of the power
supply. A fast freewheeling diode (Schottky type, forward recovery time=0.9µs), mounted in
parallel to each sub-circuit containing 3 capacitors, will keep the capacitor bank balanced in
case of failures (open circuits, lack of charge).
                                                                       EDMS No.
                                                             342797 rev. 0.1-draft
                                                                                      Page 9 of 11

  6.5 TRIGGER CIRCUIT
After receiving the trigger signal (falling ramp 12V 0V) from the quench detector, the trigger
circuit provides the firing pulse for both thyristors. At the same time it stops the low voltage B
supply for 5 seconds, in order to guarantee a safe turn-off of the thyristors after the capacitor
discharge.
The heart of the circuit is a NE556 double timer triggered by the falling ramp. It produces the
rectangular shape 50ms firing pulse for the thyristors (output 2) and stops at the same time
the low voltage B power supply for 5s in order to guarantee a safe turn-off of the thyristors
(output 1). The firing pulse is transferred to the thyristors with the help of two current
transformers (ratio 2:1).
The trigger circuit requires +15V/1A DC stabilised power.


  6.6 CHARGE DETECTOR
The charge detector circuit signalises to the control system whether the power supply is
correctly charged. In case of a power supply failure, this signal will prohibit beam injection.
During operation with beam or magnets ramped to current levels above injection, this signal
will not cause a beam/power abort, but send a warning to the control system that the specific
power supply is no longer available. The “power supply charged” signal will be sent if 90%
of the nominal voltage is reached, whereas the “power supply not charged” signal will be
given at 80% of the nominal voltage. For the time being the nominal charging voltage is U nom
=450V (Uon=405V, Uoff=360V).
The capacitor bank of the power supply consists of 2x3 Aluminium electrolytic capacitors
(4.7mF/500V) circuited in parallel. In addition each group is protected by a free wheeling diode
circuited in parallel to the capacitors. The two groups of 3 capacitors each are connected in
series giving a total capacitance of 7.5mF/1000V. The input of the charge detector consists of
two voltage dividers across each group of 3 capacitors. The output of these dividers (+10V for
the positive branch, -10V for the negative branch for Unom) is connected to two comparators
(LM311) wired as Schmitt-triggers. The reference for these comparators is given by 10V
reference of the Zener type. In order to use a single reference the negative branch sums the
output of the divider and the 10V-reference signal. Both comparator outputs are connected
together with diodes forming a logical AND, which is controlling a relay for the output signal. In
case the input voltage is smaller than U nom the comparator outputs sink a current of about
15mA to ground. As soon as all capacitors are charged the current drops out. The positive
feedback used in the Schmitt-trigger configuration guarantees a fast single transition. The
relay has two working contacts one for the output signal and a second one for switching the
indicator LED’s mounted on the front panel (GREEN for charged, ORANGE for not charged).
        The charge detector circuit requires ±15V/1A DC stabilised power.


  6.7 CHARGE MONITOR
The charge monitor circuit provides a signal for the acquisition and monitoring controller
(DQAMC), which is equivalent to 1/100 of the voltage across the capacitor bank. The signal will
be used for diagnostic purposes i.e. test discharge of the power supply for verification of the
operational status of the capacitor bank and status of the quench heater.
The capacitor bank of the power supply consists of 2x3 Aluminium electrolytic capacitors
(4.7mF/500V) circuited in parallel. The two groups of 3 capacitors each are connected in series
resulting in a total capacitance of 7.5mF/1000V. The output voltages of two dividers (1/100)
across each group of 3 capacitors are added and connected to the input of an isolation
amplifier (AD210BN). The output signal of this amplifier is then available for further processing
in the AMC.
The charge detector circuit requires +15V/100mA DC stabilised power.
                                                                      EDMS No.
                                                            342797 rev. 0.1-draft
                                                                                    Page 10 of 11

  6.8 CURRENT MONITOR
The current monitor circuit provides a signal for the acquisition and monitoring controller,
which of equivalent to 1/25 of the current in the quench heater circuit. The signal will be used
for diagnostic purposes i.e. test discharge of the power supply for verification of the
operational status of the quench heater.
The current monitor circuit is based on LEM HAS 100-S current sensor with a galvanic isolation
between the primary circuit (high power) and the secondary circuit (electronic circuit).
The current detector circuit requires +5V/12mA DC stabilised power.


  6.9 SOFT START CIRCUIT
In order to avoid high peak power, the circuit limits the current during the charging of the
capacitor banks (Icharge<20mA, Pmax (3 capacitors)10W). As an extra advantage the current
limitation makes it possible to reduce the final charging resistance to 1k.
The current is limited by a series connection of three resistors (20k, 10k and 1k10W
each). Two of these resistors can be short-circuited with the help of relays controlled by a
NE556 double timer. The timing sequence is to short-circuit the first resistor after 400s and the
second after 1200s leading to a total charging time of about 25 minutes. The trigger for the
timer is automatically generated as the circuit is powered. As the operation of components like
MOSFET-transistors or photo-triacs is not recommended for circuits exposed to irradiation with
high-energy particles, the use of relays is the only feasible solution.
The charge detector circuit requires +15V/1A DC stabilised power.


  6.10 INTERNAL POWER SUPPLIES
Internal voltage levels are produced with two power supplies. One will provide 2x450V DC, as
charging voltage of the capacitor banks and a second stabilised power supply with 2x15V DC
will feed the electronic sub-circuits.

  6.11 CONNECTION TO EARTH
The housing of the power supply is directly connected to earth. The analogue ground point of
the power supply is connected to earth via a 1M2x500kresistor in parallel with a 63mA
slow blowing fuse.
                                                      EDMS No.
                                               342797 rev. 0.1-draft
                                                                 Page 11 of 11




7. DIAGRAM
Control electronic and power circuit diagram

				
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