ESRF PSG safety for equipment and personal related to power converters 2 nd POCPA 15th of June 2010...

ESRF PSG safety for equipment and personal related to power converters

2nd POCPA 15th of June 2010

Jean-François Bouteille

Jean-François Bouteille 2nd POCPA June 15th 2010 2

ESRF Power Supply Group equipment

• 15 main families power supplies from 100kW up to 1MW.• About 500 corrector channels from 5W up to 200W• 3+2 oscillating families for the 10 Hz booster ( 3 White

circuits )• About 50 intermediate power supplies for the transfer

lines from 20W up to 2kW• One big conditioning building (HQPS) for 50Hz 20kV

mains 9.3MW,11.6MVA


ESRF PSG talk summary

•Power supply equipment safety • Electrical• Mechanical• Environmental

•Personal safety linked to power converters

• Status of procedure for accelerator personal


Power supply equipment safety• 2 main aspects:

• Intrinsic equipment protection• General indirect equipment protection

• Intrinsic protection.• Based on internal damages induced by component faults

• Energy damping• Water flooding damages

• Based on direct surrounding conditions• Mains disturbances• Temperature, humidity

• General indirect equipment protection• Based on the accelerator protection (machine safety),• Dipole converter as safety device for personal radiation safety• Fast mechanical shutter ( beam dump)


• Specificity to accelerators:• We are responsible to procure a set of converters with long running

capacity, without maintenance or repair. One hour of beam dump is rated 17k€ in 2009.

• The lifetime of equipment for large accelerators, is intended to be far above the one for public device found on the world market.

Intrinsic Protection

• As a consequence the design rules impose to envisage the energy damping mechanism to be fully safe. This means that each energy storage component needs to be carefully designed. Complex environment with multiple energy sources pushes to be cautious.

• Most of the converters are water cooled. The main advantage is the electrical efficiency but: electricity and water are not compatible. This point needs to be specially treated.


Example of design guide• Water

• Flow controller needs to be at the exit of the water cooled device.• The sensitivity of flow controller needs to be better than smallest

flow in parallel circuits!• Electricity

• Capacitors are destroyed by over charging ( to much current discharge as well as to much absorbed current ) follow-up of the serial impedance is regularly performed.

• Inductors force current to flow at tremendous voltage levels. (ex: DC relays contacts)

• Input and output circuits need to be carefully watched !• Public mains characteristic is subject to large excursion. This is, in most

accelerators, the main source of converter unavailability. (ESRF uses HQPS to clean the public mains)

• Evacuating the stored energy from the load is to be considered with a thorough analysis of the conditions and configurations. (10Hz booster power supplies)


Particular case of AC or pulsed power supplies

When 2 circuits independent AC powered (10Hz ) use the same cable trays inside long distance in tunnel, the coupling coefficient of the air transformer cannot be discarded, safety wise.


Power supply Personal safety• 2 main aspects:

• Intrinsic local worker protection• General indirect worker protection

• Intrinsic worker electrical protection.• Electrical maintenance of converters ( preventive or curative)• Based on direct surrounding conditions

• Voltage levels ( VLV, LV, HV) defining the procedure to operate

• Additional safety conditions, mechanical, thermal, etc…

• General indirect personal protection• Work of any kind inside the tunnels on or in the vicinity of the loads• The vicinity understood according to the French electrical regulation• Lock-in , lock-out, tag-in tag-out procedures.


Intrinsic worker electrical protection

• Electrical maintenance of converters ( preventive or curative)

• At ESRF, like at CERN, we have chosen to avoid and forbid all work under voltage.

• As a consequence the full sequence of Lock-Out , Tag-Out (LOTO) is applied by trained people dully authorized by the company.

• The reminding risk is the tuning work. This means debugging or adjusting is necessary when the material is alive.

• Special training is necessary to avoid people electrical shock, and arc burn effects.

• Most of the time isolating tools or no contact measurement reduce the risk linked to live contacts


General indirect personal protection

• Work of any type inside the tunnels on or in the vicinity of the loads.

• The use of the lock-out tag-out “consignation” has to be strictly followed. This means that the actions intervention and lockout, have to be temporary married. Intervention without lockout is risky, together lockout without intervention is also risky.

• The vicinity understood according to the French electrical regulation (see graph)

• Definition of the zone according to the voltage level.• Lock-in , lock-out, tag-in tag-out procedures. These procedures

are one element inside the general authorization to work inside the tunnels.


Classification of voltage levels

• These values are between any wires, including earth conductor


• Next year, (2011) these zones will be understood also outside and not only in specific rooms reserved to electricians


Mechanical protection

• The electrodynamic forces are often not correctly anticipated.

• Video• HQPS case with 65kA short circuit

between 2 x 800kVA alternators and a 1600kVA transformer

• Nobody was present in the room but the consequences could have been dramatic!




Conclusion

• These 4 aspects of the safety related issues make our job on one hand very interesting and in other hand push us to realize our large responsibility.

• Thank you for your attention


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ESRF PSG safety for equipment and personal related to power converters 2 nd POCPA 15th of June 2010...

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