M. Anghinolfi 1 , A. Calzas
1
2+ , B. Dinkespiler 2 , S. Cuneo 1 , S. Favard 2 , G. Hallewell 2 , M. Jaquet
INFN Sezione di Genova, Via Dodecaneso 33, I-16146 Genova, Italy
2 and P. Vernin 3
2 Centre de Physique des Particules de Marseille (CNRS/IN2P3), Université de la Méditeranée, 13288 Marseille, France
3 DSM-DAPNIA, CEA SACLAY, 91191 Gif sur Yvette Cedex, France
+
Communicating author. e-mail: calzas@cppm.in2p3.fr
The ANTARES collaboration is constructing an underwater neutrino telescope at 2400m depth off the French
Mediterranean coast. The telescope will contain 900 photomultiplier tubes arranged along 12 moored detection lines to detect Čerenkov light from fast muons produced in neutrino interactions in or near the array.
The detection lines are powered and read out via an underwater junction box hub connected to a 40km telecommunications cable linking the ANTARES site to the shore station near Toulon. The junction box is based on a
1m diameter titanium sphere and contains the power delivery and management system and the fibreoptic routing for all the clock and data signals for the array.
Underwater power distribution is based on a transformer with 18 independent secondary windings. Electrical energy in the range 3300-4400V AC from the shore station is transformed to 420-500V AC to power the detection lines and to
200-240V for the junction box slow control electronics. An external plugboard of wet-mateable hybrid electro-optical connectors allows the underwater connection of up to sixteen detection lines or oceanographic packages using manned or remotely operated submersible vehicles.
The triply-redundant power management and slow control system of the junction box is and based on two distinct technologies; two identical systems powered by from the internal transformer communicate with the shore through fibreoptic 160Mb/s G-links while a third battery-powered system communicates through a low power, low speed laser/pin diode link.
In this work we describe the power management and slow control system of the underwater junction box, the power components of the shore station and the 40km link cable that links them. Data from nearly three years’ continuous operation of the junction box are also presented.

+ Communicating author. e-mail: calzas@cppm.in2p3.fr
The ANTARES 0.1km
Summary
2 underwater neutrino telescope
- illustrated in fig.1 - will contain twelve detection lines spaced on a 60m sea floor grid and tensioned between anchors and submerged buoys. A total of 900 photomultiplier tubes housed in glass pressure spheres will be grouped at thirty levels rising from -2300m to
-1950m. operated submersible. Each connection point has a pair of optical fibres, used for data up- and down-links, two fibres distributing the central GPS-referenced clock for data time-stamping, and a pair of electrical conductors providing AC power in the range 420-500V.
Fig. 2a The junction box and its support frame
Fig. 1 The ANTARES underwater neutrino telescope
Data from the telescope will be transmitted to the shore station through an underwater junction box and a 40km telecommunications cable 1 , containing 48 monomode optical fibres and a single electrical conductor delivering power to the detector.
Fig. 2a illustrates the junction box structure, while figs 2b & 2c show the junction box on the deck of the deployment ship (December 2002) and at 2500m depth during the connection of prototype detection lines by the Nautile manned submersible of IFREMER, the
French oceanographic research agency (March 2003).
The junction box contains a transformer whose primary receives AC energy in the range 3300-4400V through the cable and returns current through the sea via a sea electrode 2 and electrodes buried in the ground at the shore station.
Up to sixteen electro-optical points are available at the junction box for connection of detection lines and oceanographic instrument packages via oil-filled electro-optical connectors 3 , [figs 2a,2c] which are wet- mateable in sea water at an ambient pressure exceeding 250bar, using a manned or remotely-
1
Alcatel URC3 Type 4, laid October 2001; type G24B DE 1302XB
(BBO) WB B1 multi-mode optical fibres, ø =125  m
2 Titanium with Keramox® coating, mfr Magneto BV 3125
Schiedam, Netherlands
3 Mk II hybrid electro-optical connector (4 optical fibres, 2 electrical comductors); mfr Ocean Design Inc, Ormond Beach, FL32174, USA
Rated at > 100 insertions before oil refurbishment
Fig.2b Junction box on the deck of the deployment ship
Galvanic separation of junction box outputs is assured through a transformer with sixteen individual 500Vrated secondaries. Two additional 240V-rated secondaries power the junction box internal slow control system.
The power distribution chain from the shore station to the junction box transformer is shown in fig. 3. A shore-based variable transformer adjusts the voltage sent to the primary of the junction box transformer dependent on the number of detection lines to be powered, while a 1.4H self inductance compensates capacitative losses in the 40km cable.
A central diaphragm divides the junction box sphere into a lower oil-filled transformer compartment and a hemisphere containing the slow control system and fibreoptic routing devices. The diaphragm is fitted

with a silica aerogel 4 thermal insulation blanket which also serves as a getter for water vapour.
Fig. 2c Seabed connection of a prototype detection line to one of the sixteen junction box output connectors
Fig. 3 Power distribution system from the shore to the underwater junction box
The sixteen junction box outputs are equipped with thermo-magnetic breakers 5 set to 5A threshold. In addition each breaker can be rearmed or opened by remote control should the leakage current -monitored by a 100  A resolution inductive current sensor 6 exceed a safe value.
Output breaker operation and measurements of currents, temperatures and humidity are the main activities of the triply redundant junction box slow control system. The system uses eight of the 48 fibres in the 40km cable and is based on control cards built in two different technologies. In the first, two identical cards communicate with the shore station through
160Mb/s G-links using the Agilent HDMP-1022/1024 transmitter/receiver chip set with the Photon Techno
PT5543-13-3-SC laser emitter and PT6143-155-SC receiver operating at 1550nm. Associated firmware is embedded in ALTERA 7256S ELPDs. Each card can simultaneously stream 16-bit digitized data from 48
4 Spaceloft®: Mfr: Aspen Aerogels Marlbourogh MA 01752, USA
5
Moller PKZ2/ZN6 with RE-PZK2 remote control block
6 MACC® Zero flux current monitor, 10A full scale;
Mfr: Hitec Power Protection B.V. 75555 Henglo, Netherlands internal junction box and 4 channels of 24bit data at
2,5kHz sampling from the inductive current sensors.
This latter data is used in a shore based digital signal processor for Fourier analysis of noise in the junction box transformer power system.
A third card, designed for ultra-low power operation and powered by lithium batteries is based on an Texas Instruments MSP430F149 microcontroller with 60Kb flash and 2048b RAM memory equipped with eight 12bitADC entries and 45 digital I/O ports.
This channel has a power consumption of 5  A in sleep mode and 60  A when active. The maximum power consumption of the card is 100mA for short periods, when the NEC NDL7701 P1 laser up-link module is transmitting.
The junction box slow control system has been in continuous operation since deployment in December
2002. Temperature and relative humidity have been logged during this period by the battery-powered monitor system. The relative humidity is seen to plateau around 45% and to drop during periods when the junction box is warm with the transformer powered for the operation of prototype detection lines; a strong indication that the pressure sphere is leak tight at the ambient sea pressure of 250bar.
50,00
45,00
40,00
35,00
30,00
25,00
20,00
15,00
10,00
5,00
%RH
NTC Transfo Frame low Col2
NTC Heat Spreader
0,00
11/30/02 03/10/03 06/18/03 09/26/03 01/04/04 04/13/04 07/22/04 10/30/04 02/07/05
Date(M/D/Y)/Time
Fig. 4 Long-term monitor of relative humidity and temperature in the ANTARES junction box.
The junction box passively routes bidirectional data from the detection lines to the shore using 24 fibres in the 40km cable. Four fibres transmit the central GPSreferenced clock (resolution < 100ps) to the detection lines. Two 2-16 way passive fibreoptic splitters assure redundancy in the clock transmission system
A Java-based graphical user interface has been developed for the monitor and control of the
ANTARES power delivery and junction box slow control system. Data from the junction box sensors are written at regular intervals into an Oracle data base from which alarm levels for critical sensors are read.
Reference
ANTARES Technical Design Report, version 1.0,
July 2, 2001: via http://antares.in2p3.fr