HAL Id: jpa-00223602
https://hal.archives-ouvertes.fr/jpa-00223602
Submitted on 1 Jan 1984
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
A CONTROL SYSTEM FOR CRYOGENIC INSTALLATIONS
J. Auguères, J. Benichou, B. Kadir, F. Kircher, J. Sellier
To cite this version:
J. Auguères, J. Benichou, B. Kadir, F. Kircher, J. Sellier. A CONTROL SYSTEM FOR CRYO- GENIC INSTALLATIONS. Journal de Physique Colloques, 1984, 45 (C1), pp.C1-649-C1-652.
�10.1051/jphyscol:19841131�. �jpa-00223602�
JOURNAL DE PHYSIQUE
Colloque C1, supplkment au no 1, Tome 45, janvjer 1984 page Cl-649
A CONTROL SYSTEM FOR CRYOGENIC INSTALLATIONS
J.L. AuguSres, J. Benichou, B. Kadir, F. Kircher and J.C. Sellier C.E.A. / S a c J a y , DPh/PE - STIPE, 91191 Gif-sur-Yvette, F r a n c e
Rksumk - Un syst6me de contr8le modulaire a 6th dkvelopp6 pour l'automati- sation des syst&mes cryogkniques. Le syst&me est b2ti autour d'un microproces seur ; on a dCveloppk des cartes d'interface conventionnelles et sp4cifiques aux applications cryogkniques. Un logiciel sp6cial a 6th kcrit dans le but essentiel de permettre aux utilisateurs une kcriture et une modification faciles de leur programme de contrale.
Le prototype de ce systeme fonctionne depuis plus d'un an.Le systhme est maintenant disponible commercialement ; on l'utilise et on prQvoit son usage sur plusieurs installations cryogkniques dans lesquelles le labora- toire est impliquk.
Abstract - A modular control system has been developped for the automatiza- tion of cryogenic systems. The hardware has been built around a micropro- cessor ; conventional and specific modules for cryogenic applications have been developped. A special software has also been written, the first aim of which being an easy writing and modifying ot the process control by the users.
The prototype of this system has been operated for more than a year. The system is now commercially available ; it has been used and is under consideration for several cryogenic projects in which the laboratory is involved.
INTRODUCTION
The development of advanced cryogenic systems requires more and more automatization ; one or several of the following reasons can justify this affir- mation : the complexity of these systems generally increases with their size ;
they must be very reliable and safe ; an industrial development implies that they must work without a skilled staff in non cryogenic surroundings (plants,
hospitals, ... ) and finally the running cost must be minimized.
The opportunity to develop such a system has been given to Saclay through the construction of a magneti\ separator prototype, using a superconducting
solenoid. Meant for a plant, this installation must be fully automatized ;
so, it is equipped with a built-in refrigerator working in closed cycle and with a control system, enabling to run the system in an fully automatic mode, from the cooldown to the keeping of the solenoid under excitation.
After successful tests at Saclay, the licence for this system has been sold by the CEA to the company Mecilec, which now commercializes it under the trademark Syclop.
I - REQUIREMENTS FOR A FULLY AUTOMATIC CRYOGENIC SYSTEM
The control and monitoring of the different phases of a cryogenic process can be done through :
. on/off inputs and outputs
. analog inputs and outputs, particularly cryogenic ones : temperatures, levels, heaters ...
. regulation, supervision and safety functions
. and more sophisticated functions such as counting, temporization, ramp
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19841131
C1-650 JOURNAL DE PHYSIQUE
generation, comparison with a status or a threshold, calculation, message log ...
The aim of the system is to give to the user all these possibilities for a medium size process having a cyclic operation, typically with :
. 100 to 200 on/off parameters
. 50 to 60 analog parameters
. 10 adaptive control loops
. 300 to 500 steps of sequential operation.
I1 - THE "GRAFCET" EXTENDED TO PROCESS CONTROL
The "grafcet" is a simple and rational method for representation of sequential automatic control systems ( 1 )
Grafcet basic elements are step and transition :
- a step can :
. control on/off parameter states, analog parameter values, execution of calculations, execution of instruction programmes, timers and counters
. modify control constants
. drive control loops
. output messages to the printer ...
- a transition can be described by a logical combinaison of tests on on/off parameter states, mesured or calculed analog parameter value, time delay durations, counter values, control parameters values, state of a Grafcet step ...
Divergences and convergences (and or) are also possible.
I11 - HARDWARE
A complete hardware has been designed. The system is build around a SlOO (IEEE 696) bus and is monitored by a Zilog 2 - 8 0 microprocessor.
The system cards consist of a CPU card and a memory card. A floppy disk controller and two 315K floppies can be added for local software development and loading. The 1/0 cards are connected to the process via connection boards included in the cabinet.
Card description is given in Table I ; special attention has been given to the insulation. Up to 18 cards can be plugged in a chassis. A main DC power supply is connected to the bus while a lot of auxiliary powers provide multiple insulated sources for the cards. Immunity against main power glitches or switch off are provided by an insulated transformer and an ininterruptible power supply.
A display and a line printer can be interfaced. A special asynchronous RS 232 Link is reserved to support a local area network used when several systems are needed.
The prototype is shown on Fig 1
Fig 1 - The system prototype
Central processor
unit I
I
CARD TYPE
RAM or ROM Memory Floppy disk controller
ISOLATION FEATURES, RESOLUTION
Digital input or output
Analog current input
Analog voltage input
Frequency or coun ting input Cryogenic tempe- rature measure- men t
Helium level measurement
I
Table I : Card description 1 500 V 1 000 V 1 000 V 1 000 V 1 000 V
1 000 V Analog current
output Analog input voltage sub system
z 80 B + AMD 9511 processors -
3 asynchronous serial links Real time clock - 4K byte ROM and 4K byte RAM
8 x 8K byte memory Software configurated
1 000 v
1 000 V
2 x 315K byte
Input or output software configurated
4 to 20 rnA . 10 bit
Unipolar or bipolar inputs 100 m V to 10 V . 10 bit
1 Hz to 10 kHz range 10 to 16 bit
Sensors : carbon resistor, CLTS or platinium ; current range l p A to 1 mA. 12 bit Super conductive sensor Current 50 mA typ.
4 to 20 mA. 8 bit
16 differential or 32 single ended inputs. ADC resolution 12 bit Microprocessor controled
I V - S O F T W A R E
The general organization of the software is shown on Fig 2 A special lapguage has been develop-
ped for the system ; it is based on the grafcet method as indicated before. Its main particula- rities are :
- each parameter is identified by
the name assigned to it by the user. Real tame Kernel - programming with words from the nesntnnt ~~b~~~~
natural vocabulary of automation specialists - PID control loops can be treated - use of a compiler to translate the
netrork
program into machine code, to detect errors...
N"l mnt
- on and off lines tests possibilities.
Fig 2 - Software organization
JOURNAL DE PHYSIQUE
V - A P P L I C A T I O N S Installations now in operation :
. Sepma : ore separator prototype using a superconducting solenoid and working in closed cryogenic loop ; after the setting, has been periodically in
fully automatized operation for more than a year.
. Helium liquefier-refrigerator: in the frame of a collaboration between AirLiquideand Saclay,the system has been put in a modular helium liquefier-refri- gerator which can produce between 40 - 70 1 per hour. This is the first truly automatic standard helium liquefier - refrigerator ( 2 ) .
. Gaz control and epuration system for the detectors of a very large experience now under installation in the Frejus tunnel, to measure the proton life -time.
Installation under development :
. Test facility for the Tore Supra coils which will be tested two by two before their final installation. The system will control the cryogenic and the electrotechnical processes.
. Post accelerator using superconducting cavities to be put after a Van de Graaf at Saclay; this will be the largest installation to control, with about 500 digital and 150 analog I/O. Five systems will be used in a network : one master, three slaves for the eight cryostat management and one installed in a helium liquefier similar to the one described above.
C O N C L U S I O N S
...
...
A modular process control system has been completely developped.
Primitively designed for cryogenic processes, its possibilities are large enough to be now commercialized by a manufacturer which is involved in rather different process controls. Its practical modularity, its industrial design and its plain language make it use very simple.
R E F E R E N C E S
(1) See for example : M. BLANCHARD : Comprendre, martriser et appliquer le Grafcet - Editions CEPADUES
( 2 ) G. GISTAU, J. MART : The world's first truly automatic standard helium
liquefier - refrigerator. 1983 Cryogenic Engineering Conference.
