XFEL Grounding (3)

1. XFEL hybrid ground system2. Infrastructure to be included in facility ground3. Local grounding areas

H. KapitzaEMC Meeting 13.11.06

Introduction• This talk is not about “We do it this way.” but rather

about “How shall we do it?”• I want to collect material, experiences, and ideas.• It might have been better to have this meeting after the

XFEL Technical Coordination Meeting tomorrow, but I didn’t want to shift it once more. We might as well gather useful input for that meeting.

• On Nov 8, 2006 I reported in the XFEL Project Meetingabout “EMC @ FLASH & XFEL”: http://xfel.desy.de/projectgroup/index_eng.html

In a large facility, where many ground conductors would be > λ / 10 long, a hybrid multipoint ground system should be used.

• Local SP ground areas (< λ /10) keep ground Z & noise potentials low.• Cables can be run between local devices (with some restrictions).• Grounded cable connections are forbidden between local areas.

They won’t work well anyway since shield/noise currents will be high.

Facility groundLow Z Facility Ground

XFEL Facility Ground

• Due to its length >> λ(2 MHz)/10 = 15 m the XFEL facility needs a

hybrid ground system where many local single-point grounding areas are

connected to a common facility ground.

• In order to push its impedance as low as possible, the common facility

ground (plane) should include as much through-going metal structure as

possible (tubes, pipes, cable trays, remesh,. . .).

• Since these components will not really form a plane, aim at a mesh size

≈ λ(2 MHz)/50 = 3 m.

Röntgenlaser XFEL

Mounting rails in unrolled inner tunnel surface

y

z

ze

y

49

30h

3,25

7,5

a 15 cmr �

22

50

30h

82,75

a 15 cmr �

22

5 5

�F

Dynam. Lastensiehe Seite 28

Systemzubehörfür HTA 50/30 und 49/30:

• VerankerungslaschenHKZ, siehe Seite 40

7,5 kN mit HSR - M20 �

HalfenschraubeTyp HS 50/30 oderTyp HSR 50/30inkl. Mutter

(reduziert a : siehe S. 26)r (reduziert a : s. S. 26)r

HalfenschraubeTyp HS 50/30inkl. Mutter

warmgewalzt

Vf = Haropor-Vollschaumfüllung

VUS 52/34 (siehe S. 37)

Vf = Haropor-Vollschaumfüllung

VUS 49/30 (siehe S. 37)

Gewicht mit Ankern [kg/m], Ausführ. fv /A4

Profilquerschnitt A [cm² ]

Schwerpunktabstand e [cm]

Ankerausführung

Höhe h [mm]

Füllung

Unterlegscheibe f. Abstandsmontage (s.S.30)

Werkstoff , Ausführung (Erläut. siehe S. 6)�

Trägheitsmoment [cm ]

Widerstandsmoment [cm³]

4

Zug 150°

Querzug 15°

in Längsrichtung mit HSR-Schr.

���

����

Zulässige

Punktlast,

B 25� �

Halfenschiene Typ:

Werkstoff/Ausführ.(siehe S.6):

Länge[mm]

Typenauswahl Standardlängen

(Andere Längen siehe Seite 9)

Bestellbeispiel:

oder Bestell - Nr. 0001.080-00107HTA 50/30 - A4 - 550

Anker-anzahl

warmgewalzt

�

Anmerk. siehe Seite 23� �-

HALFENSCHIENEN TYP HTALaststufe 10,0 und 12,0 kN

Bestell - Nr.fv=feuerverz.

Bestell - Nr.A4-Ank.A4 �

� Werte in Klammern gelten für Kurzstücke 150/200/250 mm� = Profil und Anker aus Edelstahl A4A4-Ank.A4

*) Bei Bestellung vermerken: "3 Ank".

� = Profil und Anker aus Edelstahl A4A4-Ank.A4

Hinweis:

, Last-stufen bis 12 kNin alle Richtungen,

siehe Seiten31 - 34und Katalog BD.

Gezahnte Halfen-schiene HZA 38/23DYNAGRIP

�

10,0 kN

12,0 kN

(12,0 kN )� 10,0 kN

12,0 kN

(12,0 kN )�

�

3,20 / 3,00

4,14

1,56

3,35 / 3,21

3,82

1,77

S235JR (St 37-2)

90

B

A4 - Ank.A4

90

B

A4-Ank.A4S235JRG2 (RSt 37 - 2) W 1.4571/1.4401 W 1.4571/1.4401

fv , wb fv , wb

HTA 49/30HTA 50/30

Jy = 5,24

Wy = 3,36

Jy = 4,35

Wy = 2,45

Jz = 14,22

Wz = 5,80

Jz = 13,95

Wz = 5,58

HTA 49/30

222233335

25

22223335

25

150200250300300350400550

10506070

HTA 50/30

150200250300350400550

10506070

HTA 49/30

HTA 50/30

*)

.080-00301

.080-00302

.080-00303

.080-00304

.080-00305

.080-00306

.080-00307

.080-00308

.080-00309

.080-00003

0001. . . . 0001. . . .

.080-00101

.080-00102

.080-00103

.080-00104

.080-00105

.080-00106

.080-00107

.080-00108

.080-00001

.070-00301

.070-00302

.070-00303

.070-00304

.070-00305

.070-00306

.070-00307

.070-00308

.070-00003

.070-00101

.070-00102

.070-00103

.070-00104

.070-00105

.070-00106

.070-00107

.070-00108

.070-00001

HCRW 1.4547

�

14

4 longitudinal grounding rails

Next Steps:• Gain better understanding and some numbers for the

following points :– energy radiated from the pulse cables and its absorption by the

tunnel mesh– pulse cable cutoff frequencies and consequences for the cable

trays• Include other tunnel metal in the facility ground.• Design local SP or MP grounding areas:

– repeated standard sections in the linac– special considerations for the injector

• Define XFEL cabling rules.• The XFEL Technical Coordination Meeting will be a good

forum for such topics. Next on Nov 14, 2006.

Inventory of metallic tunnel infrastructure:• Helium pipe DN 200• 2 RF cooling DN 40• suction line DN 50• 2 compressed air DN 50• nitrogen DN 25• fire water DN 125• 2 VE water return DN 300 and 100• cold water DN 100• VE water DN 300• smoke channel 1050 x 620 mm

• 6 cable trays• 4 grounding rails• wave guides• 8 pulse cable trays• module housings• beam tube

• Collect the resistances and inductances of these components.• Which are local, which are going through?• Allocate cable trays according to EMI level, not according to DESY group.

50 m long linacstandard sectionof 4 modules

2 modules with attached waveguides

RF distribution (schematic):

• Are the waveguides suitable local ground references?

Another type of local ground system (new sync laser hut)

Schematic overview of the TESLA XFEL Injector

Injektor II

Injektor I

Booster

3rd Harm.

BunchCompressor

Injector IBunch

compressor section

Injector II

3rd harm. section

4 TESLA Modules

0 m 50 m 80 m ca. 150 m

XSIN XSE

Some questions to answer• What useful and noise signals do you use or emit?• In case you don’t know, measurements at FLASH can

help. We have some equipment.• The signal frequencies are very important to know.• I guess, tomorrow’s meeting will bring us forward in

these matters.

Practical ground systems are usually a combination of series and parallel single-point systems.

• Group high-power and low-level circuits on separate ground return wires.

• Most systems require three ground returns: signal, noisy, and hardware.

• Connect the three grounds at one point.

• The safety groundshould be connected to the hardware ground at the (rack) ground point.

An example of the three-ground system shows how different types of ground currents are returned separately.