Power Supplies (CMS Tracker)

• Proposed Scheme• Possible Grouping• Voltage drop• Power dissipation• Prototypes & PSU specs• System Architecture • Alarms and software controls• Test procedures• Cable selection

Introduction• Power in parallel one group of n APV25

hybrids, with roughly 100 metre long cables.• Place the power supply where it is accessible!

Power electronics BREAKS DOWN!

Schemes

Grouping problematic

• How much of the tracker are we willing to risk due to a catastrophic fault.

• Power distribution to the rods and location of the sense wires.

• Voltage stability on very high current lines (filtering, sudden load variations).

• Detector biasing, (how many HV generators per group).• Cable cross-sections and power dissipation.• Technology of the power supplies and mechanical

constraints.

A possible grouping (In):Possible Inner Barrel GroupingL1 ds 6+6 28 rods 56 (36 APVs/group)6xH2 L2 ds 6+6 38 rods 76 (36 APVs/group)6xH2L3 ss 4 46 rods 23 (48 APVs/group)12xH1L4 ss 4 56 rods 28 (48 APVs/group)12xH1Total Inner(1 Side) 183 PSUs7200 APVs

Layer I@2.5V I@1.25V I@0V W Nr. of groups1 6.6A 3.1A 9.7A 20.4 56 2 6.6A 3.1A 9.7A 20.4 763 9.1A 4.1A 13.2A 28.0 234 9.1A 4.1A 13.2A 28.0 28

Voltage drop

Power dissipation

Prototypes• The prototypes follow the “unipolar” scheme.

The basic unit consists of a Power Supply Unit (PSU). This is capable of powering a complete detector module (or groups of modules) both for what concerns low voltage and high voltage (detector biasing).

• A mechanical drawer (Power Supply Module – PSM) houses two PSUs. A certain number of PSMs are placed inside a crate. Connections between the PSMs and the cables, leading to the detector module groups, are implemented through a network of relay switches which guarantee fail safe operations on the system.

The prototypes that we will receive follow the guidelines stated above. Namely they will consist of a PSM housing two complete PSUs (low and high voltages) together with a crate with back-panel relay switches. A controller (supplied by the prototype manufacturers) will allow programming of the PSUs and verification of the safety features implemented.The specifications (max current, voltages, etc.) are as follows (N.B. per PSU):

System Architecture (1)

• PSU: is the ensemble of low and high voltage regulators for each detector group.

• PSM: is a complex module housing 2 PSUs or more and their control logic.

• The system is organized in PSM arrays (128 PSUs), which are driven by dedicated controllers.

• The Controllers are interfaced to the CMS slow control.

Connections (1)

PowerUnit

System Architecture (2)

PSM

The PSMs can be “Hot Inserted”.

Alarms & Controls• Current Limits, Over Voltage checks are hardwired at the

PSU level.• Trip procedures, Ramping and Updates are executed by

software either at the array controller level or at the PSM level.

• Hardwired General Reset.• Transitions from Stand By On to Stand By Off (and vice

versa) can only happen when the Output Voltages are at zero.

• On the PSMs front panels there are a few LEDs indicating status.

• Some of the Alarms are also hardwire summed and brought out as a “fast” logical alarm to the rest of the world.

Software Controls

• Array controllers are interfaced to CMS slow control (Ethernet).

• Monitoring, procedure executions, etc. can be executed either by the Array controller or by downstream CPUs.

• All external commands are filtered by the Array Controllers.

• OPC (OLE for Process Control) is an open interface based on the OLE/COM (now ActiveX) and DCOM technology.

• OPC offers “Plug&Play” connectivity between disparate hardware devices.

• OPC client applications can communicate with the OPC server to exchange data in a standard way. Each device property is accessed via an OPC item.

Manufacturers are asked to provide:OPC serverC/C++ libraries, both for Windows and Linux

Automatic Test Setupfor CMS-TK Power Supply1. Torino's goal is to develop a remote

controlled test fixture to validate automatically all CMS Tracker Power Supply units (PSU).

2. The list of measurements to qualify the performances of each PSU will include:

• Noise test• Over voltage protection test• Over current protection test• Sense break-down test• Interlock test• Security test

Working schemeClose collaboration between Torino and Firenze is

needed since the beginning: the development of the Power Supply unit prototype(s) should go in parallel with the production of a “prototype” test fixture in order to check its consistency and technology.

• Production scheme:• Develop prototype test fixture (fall 2000 – spring 2001)• Check the complete test procedure on PSU prototypes (spring 2001 -

fall 2001)• Produce the remote controlled test fixture (fall 2001 - spring 2002)

At regime

• 3 Automatic test setup will have to be produced and distributed: 1Company + 1To + 1Fi

In Production:• 1. The Company will use the automatic test

setup in its production run.• 2. To + Fi to cross check the company.

CABLES

High currents, low voltages• As low as possible Z, so that each detector

group can be thought of as a unit decoupled from the rest of the world.

• Low inductance, high capacity (same as before) in order to minimize voltage overshoots due to current variations.

E.M.I. and Shielding

• To provide some immunity from E.M.I. the power cables of each group must have a low D.C. resistance and a low impedance.

• The power supplies of each group must be “floating” and their Common connected inside the detector.

• Cable shielding must be investigated in a setup as close as possible to the final one.

Conclusions & Time schedule• Project is well underway.• Close feedback between us and the prototype

manufacturers, addressing system and quality issues but NOT detailed PSU schematics.

• First prototype 0 is under test at Firenze, and will soon go to Torino where the text-fixture has to be debugged.

• June-July we will receive final versions of the prototypes.

• By then we will start working towards the Power Supply System test with final CMS electronics.