CERN - European Organization for Nuclear Research - Physics Department

Configuration
The rack is powered from the Canalis system through the Twido box.
The Twido box is a module plugged directly into the Canalis which is a bar bus supplying three phases 400V ac power.
The box contains the rack main circuit breaker protecting the electrical network from overload and a small PLC (SCHNEIDER TWIDO PLC).

The DCS communicate with a concentrator PLC (SCHNEIDER PREMIUM PLC) using MODBUS TCP/IP protocol.
The rack breakers are controlled by the protection PLC (TWIDO) which uses JBUS protocol on several RS485 lines to communicate with the concentrator PLC.

The demonstrator rack is a single phase installation with three remotely and one manually controlled power connectors (Harting) on a distribution frame inside the rack. An additional connector (Burndy) is used for the turbine unit.
The breaker current limitation for each connector is 16A (except the turbine connector).

Control
The rack and its three remote breakers can be controlled with PVSS or with the PLC Man Machine Interface (MAGELIS).

The Twido box has an interlock input connected to the RSS (Rack Safety System) which is a part of the DSS (Detector Safety System). In case of smoke detection inside the rack, the RSS open a contact which switches off the rack main breaker.

We do not have a RSS for the demonstrator rack thus we use the AFD-CIE (Automatic Fire Detection – Control & Indicating Equipment) to provide the interlock contact. If smoke is detected inside the rack the AFD-CIE open the corresponding contact.
The smoke is detected with a smoke detector on the monitoring board which is placed in the turbine unit (between the two turbines on the front of the rack). The alarm is communicated to the AFD-CIE through an interlock link.

In addition with the smoke detection, the rack monitoring system (inside the turbine unit) provides a rack over temperature alarm. through the Thermo Switch.
A Thermo Switch opens when the rack internal temperature is too high (above 40°C).
This interlock contact is connected to the rack electrical distribution frame inside the rack. Its status is read by the protection PLC which switches off the rack if open. There is a second status reading by the monitoring system (information communicated to the DCS via CANbus).

Configuration
The racks are powered from Hazemeyer ZTBE type drawers. Indeed, LHCB and ALICE will reuse the LV switchboards from LEP.
Drawers are interfaced to a concentrator PLC (SCHNEIDER PREMIUM PLC) which communicates with the DCS using MODBUS TCP/IP protocol.

The LHCB demonstrator rack is a single phase installation with seven manually controlled power connectors (Burndy) on a distribution frame inside the rack. One of these connectors should be used for the turbine unit.
The breaker current limitation for each connector is 16A.

The ALICE demonstrator rack is equipped with a prototype of the future electrical distribution frame. The connection is made directly on a terminal pad inside the frame. The 3P+N power network is distributed on three four poles 16A breakers. The loads should be connected in a way to balance the currents on the three phases.

Control
The racks can be controlled with PVSS or with the PLC Man Machine Interface (MAGELIS). It is also possible to manually control the drawers with the buttons on there front face. Each drawer can be configured for local or remote control (remote control includes MMI).

The ALICE and LHCB smoke detectors, located on the monitoring board inside the turbine unit, are connected on a proprietary bus to the AFD-CIE (Automatic Fire Detection – Control & Indicating Equipment).
In case of smoke detection, an alarm is generated (sound and light alarm); the CIE indicates which rack tripped the alarm and opens the corresponding contact.
This contact is connected in series with the Thermo Switch in the drawer 48V interlock loop.
The above configuration is true for the ALICE & LHCB demonstration racks. But in the LHCB experiment the CIE & Thermo Switch contact status are read by the DSS (Detector Safety System) which in its turn open the drawer interlock loop.
We can not implement this topology because we do not have a DSS.

In the experiments one drawer can supply two or three racks.