The LBDS trigger and re-trigger schemes

Technical Review on UPS power distribution of the LHC Beam Dumping System (LBDS)

A. Antoine

The LBDS trigger and re-trigger schemes 2

Outline

• Definitions• LBDS Trigger Synchronization & Distribution• Trigger Synchronisation Unit• Re-trigger Unit• Power failure tests• Summary

The LBDS trigger and re-trigger schemes 3

Definitions

• Fault tolerant:– Redundancy– Increasing availability and

productivity in case of a failure

• Fail-safe:– Safety functionalities– Known state in case of a

failure• Redundancy can be a part

of the Safety (SIL levels)

Fail-safe

Fault tolerant

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LBDS Trigger Synchronization & Distribution(Reminder)

Fault-tolerantFail-safe Re-trigger lines

A

B

A

B

Generator 1

… Generator 15

PTU

PTU

PTU

PTU

Power TriggerUnit

RTB

RTB

RTB

RTB

Re-trigger Box

RTB

TFOA

TFOB

Trigger Fan-out

Delay > 2 LHC Revolution

(2*89 s)

TSUA

TSUB

Client Interfaces

Frev

Trigger Synchronisation

Unit

The LBDS trigger and re-trigger schemes 5

LBDS Trigger Synchronization & DistributionTSU - VME Crate

• CPU RIO 60xx• CTRV (2x)• Optical to Electrical converter• TSU & Interface – B • TSU & Interface – A• BLM board (Rear side)

+ BLM

INTERNALPOWER FAILURE

SOURCES

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Trigger Synchronization UnitMain Features

• Hardware– 2 VME TSU redundant boards– 2 VME signal interface boards– 1 VME backplane

• RF-signal recovery capability (DPLL)• Fault tolerant & Safe behaviour

(Redundancy + Sync. crosscheck)• Multiple Fail-safe Dump request client

detectors• Remote diagnostic (VME)• Injection Kicker AGK window

generation• Injection inhibit capability (BIS)

The LBDS trigger and re-trigger schemes 7

Trigger Synchronization UnitBlock Diagram

Digital Phase Locked Loop

Dump Request Management

Beam revolution Frequency

Redundant TSU Communication

VME

Dump Request Client Interface

Digital Phase Locked Loop

Dump Request Management

Re-phasing

Beam Revolution Frequency

Redundant TSU Communication

VME

TFO-A

TSU-A

RBRF

TRGS

RBRF

TRGS

TSU-B

SBDT

TFO-B

SBDT

TFO-A

SBDT

TFO-B

SBDT

External Clients

External Clients

TriggerP

ulse

CurrentL

oop

FrequencyD

etector

Non-A

mbivalent

State R

elay

Non-A

mbivalent

State R

elay

Supervisory&

Diagnostic

Supervisory&

Diagnostic

CurrentL

oop

TriggerP

ulse

FrequencyD

etector

Re-phasingDump Request Client Interface

ABDT ABDT

DRBRFDRBRF

BRF BRF

Fail-safe

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TSU-A TSU-B Status Action Dump Type

OK OK All OK nothing Synchronous

OK FALSE TSU-B oscillator failure

TSU-A Dump immediatelyTSU-B disable its own dump

request Synchronous

FALSE OK TSU-A oscillator failure

TSU-B Dump immediatelyTSU-A disable its own dump

request Synchronous

FALSE FALSE Timing failureTSU-A & TSU-B dump

immediatly

SynchronousOr Asynchronous

Or Synchronous-Asynchronous

Trigger Synchronization UnitFail-safe

• Mainly Based on pulsed signals• Signals crosschecked used for failure detection:

– BRF (Beam revolution Frequency) – DRBRF (Delayed Recovered Beam Revolution Frequency)– Internal Status

• Discrepancy Detection Concept• Synchronisation failure between TSU-A & TSU-B

The LBDS trigger and re-trigger schemes 9

Trigger Synchronization UnitDump Output Managment

• Different drivers – redundancy: Fault-tolerent• All dump trigger outputs checked for Diagnostics• Asynchronous line surveillance: Fault-tolerent

Common +12V

The LBDS trigger and re-trigger schemes 10

Re-Trigger Unit Trigger Delay specifications

• Re-trigger unit is based on:– The trigger delay board:

• is a back-up system that generates an asynchronous dump trigger in case of problems with the synchronous dump trigger

• Exclusively based on analogue electronics• The trigger delay generates an output pulse 200μs after the input

trigger• Two internal 24V power supplies: Fault tolerant• If both power supplies fail or in case of mains failure, supply voltage

is maintained by internal capacitors: Fail-safe (Up to 30 min)

– The mains monitor board:• Input & output power supply survey• Asynchronous dump trigger capabilities

The LBDS trigger and re-trigger schemes 11

Re-Trigger UnitTrigger Delay Interlock Management

• Interlock circuit:– Input disconnected– Output disconnected– Internal failure (low voltage of oscillator capacitor)– Generates an error signal for the PLC– NO DIRECT OUTPUT TRIGGER GENERATED

PLC(Slow control) TSU

RettriggerDelay

Interlock

Arming/Dump SynchronousTrigger

AsynchronousTrigger

Retrigger line

Power failure on +12V TSU – VME crate !

The LBDS trigger and re-trigger schemes 12

Re-Trigger UnitMains Monitor

• The “Mains monitor” board:– Monitor mains 220V of the retrigger crate– Monitor +24V from the power supply– Generate an ASYNCHRONOUS dump in case of a failure– Adjustable Delay (hard coded: 20ms to 100ms)

PLC(Slow control)

RettriggerDelay

Interlock

Arming/Dump SynchronousTrigger

AsynchronousTrigger

Retrigger line

Mains Monitor

TSU

The LBDS trigger and re-trigger schemes 13

Power Failure TestsCases

1 A real correct dump2 LHC: VME crate powering off from CCC3 Test bench: VME crate powering off locally

The LBDS trigger and re-trigger schemes 14

Power Failure Test ResultsA correct system behaviour

DUMP REQUEST ON TSU-B

DUMP REQUEST ON TSU-A

SYNCHRONOUS DUMP TRIGGER

RE-TRIGGER (ASYNC)

RE-TRIGGER LINE

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Power Failure Test ResultsPowering off VME crate from CCC

DUMP REQUEST

SYNC. TRIGGER

BRF MISSING

ASYNC. TRIGGER

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Power Failure Test ResultsPowering off VME crate in the test bench

BRF DISAPEARINGPOWER FAILURE

DPLL UNLOCKED

SYNC./ASYNC. TRIGGER ASYNC. TRIGGER

The LBDS trigger and re-trigger schemes 17

Power Failure TestsAnalysis

• General, in all cases:– TSU units issue synchronous & asynchronous trigger

• LHC: VME crate powering off from CCC:– BRF missing detection– Synchronous dump type

• Test bench: VME crate powering off locally– DPLL unlock detection– Synchronous-asynchronous dump type

• Test difference: the BRF optical to electrical translator seats outside the TSU-VME crate in our test bench

The LBDS trigger and re-trigger schemes 18

Summary

• All power failure tests lead in the generation of SBDT and ABDT triggering signals. Unfortunately in some cases, SBDT signals can be asynchronous with the beam.

• There is still potentially dangerous common mode on the triggering paths induced by a permanent short-circuit on the +12V VME line.

• All asynchronous dump requests (mainly not executed but checked at each dump) are based on the TSUs, the only exception is a power failure of the re-trigger unit.

• A power cut on the TSU - VME crate generates a synchronous dump by the loss of the BRF signal (fail-safe approach).

The LBDS trigger and re-trigger schemes 19

End

Questions ?