SPECIFICATION

BOOSTER GMPS POWER SUPPLY

GIRDER TRIMMING CAPACITOR

Fermi National Accelerator Laboratory

P.O. Box 500

Batavia, IL 60510

SPECIFICATION # 0323–ES–282509

REV B

9/11/2026

Originated by:

Chris Jensen, Spencer Garcia-Schiefelbein Date

Reviewed by:

Salah Chaurize Date

Reviewed by:

Howie Pfeffer Date

Reviewed by:

Ramfis Rivera Colon Date

Reviewed by:

Thomas Strauss Date

Booster GMPS Girder Trimming Capacitor Spec # 0323–ES–282509, Rev. B

1 INTRODUCTION

This specification is for the capacitors in a White Circuit, a system which provides an offset AC resonant current in the defocusing (D) and focusing (F) Booster’s Combined Function Magnets

(CFM) with a minimum of 150 A (700 MeV), a maximum of 1006 A (8.05 GeV) and a period of

50 ms. The choke current is primarily DC. There are 48 of these cells in series driven by a power supply while a coupling loop on the choke maintains equal voltage across the 48 capacitor banks.

This system has been in operation for over 50 years. We are purchasing these capacitors to change the circuit’s resonant frequency from 15 Hz to 20 Hz and to match the change of the injection energy from 400 MeV to 800 MeV. The new caps will be housed in the space that presently holds the existing capacitors (Figure 4) which places several restrictions on the physical characteristics of the capacitors. A simplified electrical drawing of an individual cell of the supply is shown in

Figure 1. A new value for the capacitor bank is chosen to resonate at slightly lower than 20 Hz but for all 48 cells the same within 1%. LC conducts the DC offset current.

This specification is written for trimming capacitors. This trimming capacitor will be added as needed to each bank of capacitors to keep the circuit in resonance.

This system runs continuously for 9 months a year. It is also in a neutron and x-ray radiation field which limits the choice of the dielectric materials used for long lifetime. All materials used in this capacitor must be supplied as part of the bid. A different specification will be used for a small number of cells that have special D magnets with higher inductance.

Fig. 1 – A single cell of the Booster Gradient Magnet System

2 SCOPE OF WORK

The vendor shall supply the capacitors to satisfy all conditions of this specification.

The vendor shall ensure that the capacitors comply with the National Electric Code (NEC) and supply Material Safety Data Sheets on any required materials.

The vendor shall supply all QC documents requested from Section 5 and package units for shipment as stated in Section 6.

Fermilab will bus the capacitors together to form capacitor banks with a low impedance.

The capacitors shall not have internal discharge resistors nor series current limiting resistors nor fuses.

It is critical for correct operation that each of the 48 cells has the same capacitance within 1% to ensure correct operation. If any cell exceeds this variation, the total capacitance must be adjusted to maintain the capacitance. The ideal value for the capacitor bank is 4.35 mF. A value 1% below this nominal is chosen for the requirement. The trimming capacitors are specified in this document.

They will be used in various combinations to get a precise value to keep the circuit in resonance and adjust for slow degradation of capacitance over time.

3 ELECTRICAL SPECIFICATIONS PER CAPACITOR

3.1 Capacitance Values 22 uF (C1), 22 uF (C2), 65 uF (C3) and 108 uF (C4) +/- 5%

A single capacitor case will contain four (4) capacitor values, with a common return.

See also section 3.12 for capacitance variation over lifetime.

Fig 2 showing electrical configuration of capacitors (C1, C2, C3, C4) and bushings (B1, B2, B3, B4, BC)

3.2 Capacitor Voltage +/– 1.6 kV pk, maximum

1100 V rms

100% voltage-reversal

1.8 kV to case, either terminal

3.3 Capacitor Current, B1, B2, B3 11 A peak, 8 A rms at 20 Hz

Capacitor Current, B4, BC 45 A peak, 35 A rms at 20 Hz

3.4 Hipot Voltage

Terminal to Terminal >= 1.8 kV DC for 30 seconds

All Terminals to Case >= 2.5 kV DC for 30 seconds

Bushings B1,B2,B3,B4 tied together for terminal to terminal hipot

3.5 Leakage Current

Terminal to Terminal < 1 mA at 1.8 kV DC

All Terminals to Case < 100 µA at 2.5 kV DC

Bushings B1,B2,B3,B4 tied together for terminal to terminal leakage current

3.6 Capacitance to Case < 2 nF per case @ 1 kHz

All bushings tied together and measured to case.

3.7 Equivalent Series Inductance < 1 µH per capacitor per bushing

3.8 Equivalent Series Resistance < 2 mΩ @ 20 Hz per capacitor per bushing

3.9 Dissipation Factor < 0.2% at 20 Hz and 25 °C per capacitor per bushing

3.10 Design Type AC

DC filter capacitor design is unacceptable.

3.11 Dielectric System

Solid (or semi-solid) impregnation is acceptable and preferred.

The use of less flammable liquids (ignition temperature > 300°C) for the dielectric fluid is required if liquid impregnation is used.

The dielectric stress is to be consistent with Section 3.12 Operating Lifetime and the definition of survival therein.

The materials used in the dielectric system must be described in the bid response.

The following materials are known to be acceptable in the radiation field expected during operation because they retain their mechanical properties up to about 100 MRad

(1 MGray) :

• Polypropylene, polyethylene, Kraft paper

• Epoxy paint, polyurethane paint, metals, ceramics, many thermoplastics, mineral oils

• Viton, polyurethane rubber, ethylene propylene rubber, EPDM

The dielectric system may consist of a combination of paper and metalized plastic where no voltage holdoff in the plastic is assumed. See also Section 4.1.

The following materials must NOT be used in this capacitor because they have poor mechanical lifetime in the expected radiation field:

• Teflon or any other fluorinated polymers or fluorinated oils, silicone oil

• Polymethyl methacrylate, butyl rubber, formaldehyde thermoplastics, polyester, mylar, acetate

Radiation damage to the acceptable organic materials is similar to an increase in ambient temperature of 15°C.

3.12 Operating Lifetime > 195,000 hours of continuous operation.

1010 cycle

The capacitor shall be designed for a minimum of 95% survival within the operating parameters as defined in paragraphs 3.2, 3.3 and Figure 2.

Capacitor survival is defined as continuing to meet the < 2% change from the initial value, as stated in Section 3.1, over the operating lifetime of the capacitor, including any self-healing events.

3.13 Bushings, Electrical

Bushings B1, B2, B3, B4 and BC shall be rated for at least the current defined in Section

3.3

All the bushings may be the same size meeting the highest current requirement or bushings

B4 and BC may use larger bushings than B1, B2 and B3

All terminals of the capacitor shall be able to operate at the voltage defined in Section 3.4 with respect to the case.

See also Section 4.3 for bushing mechanical information.

4 ENVIRONMENTAL AND MECHANICAL SPECIFICATIONS

4.1 Environmental Conditions

The capacitor shall meet all requirements of this specification when operating under the following environmental conditions:

Ambient Temperature 20 to 40°C

(0°C for storage)

Relative Humidity 20 to 90 %

Radiation Dose 300 kRad/year, 10 MRad total dose neutrons, electrons and x-rays

4.2 Case Mechanical

See Figure 3 for the definition of dimensions H, W, L, B, FB, FT, M and S.

See Section 4.5 for weight.

The preferred case length, L, is less than 25.00” (635 mm), including bushings.

The maximum case height H is 6.00” (152 mm) including all tolerances and bowing in case. The minimum case height is 4.50” (114mm). The preference is for L to be smaller and H to be near the maximum.

The maximum case width W is 13.63” (346 mm) including all tolerance and bowing in case.

The capacitors shall have flanges for mounting at the bushing ends. The flange shall be unpainted, conductive metal on both sides. Corrosion protection must be used unless the case is stainless steel. This flange shall be the method for grounding the case.

The dimension from the mounting flange to the first thread on the bushing is FB and shall be 4.00 +/- 0.03” (102mm).

The mounting flange to bushing end of the threads is FT and is 6.50” (165 mm) maximum.

The mounting flange minimum hole to hole center is M and shall be 15.63” (397 mm) with a slot S of at least 0.50” ( 13 mm) x 0.75” (19 mm) wide.

If overpressure switches or other required interlocking devices are used, they must be placed in the areas indicated on Fig 3 and must not extend past the envelope of the capacitor and bushing.

Fig. 3 – Single Capacitor Dimensional and Labeling Requirements

4.3 Bushings, Mechanical

The capacitor shall have five isolated bushings with threaded studs and arranged as shown in Figure 3 with the common bushing on one end.

The bushings material shall be ceramic unless the composition of the bushings is described in detail. See also Sections 4.1 for environmental conditions and Section 3.13 for electrical ratings.

4.4 Orientation

The capacitor shall be able to operate while mounted horizontally or vertically (with bushings up) during testing.

The case will be mounted horizontally during operation.

4.5 Weight

The weight of each individual capacitor shall be less than 75 lbs. for handling.

4.6 Nameplates and bushing labels

A simplified nameplate with the following shall be applied on the same surface as the bushings and located as shown in Fig 3:

- Manufacturer’s Serial Number

- Measure Capacitance @ Test Frequency

- Date of Manufacture or Date Code

A detailed nameplate with the following shall be applied on the W side near the bushings end of the capacitor and located as shown in Fig 3:

- Manufacturer’s Name or Mark

- Manufacturer’s Model Number

- Manufacturer’s Serial Number

- Fermilab Specification # 0323–ES–282509, Rev B

- Measured Capacitance @ Test Frequency

- Equivalent Series Inductance (Typical or Nominal)

- Equivalent Series Resistance (Typical or Nominal)

- Working Voltage

- Type of Service

- Dielectric and Dielectric Fluid Type (Needed for proper disposal)

- Date of Manufacture or Date Code

Each capacitor bushing shall be labeled as shown in Fig 3 to identify which nominal capacitor is connected to the bushing

Fig. 4 – Existing capacitors installed in girder frame showing a trimming capacitor

INFORMATION ONLY

5 TESTS BY VENDOR

All test results for will be provided by the vendor.

Test data are required to be sent to Fermilab for approval before shipment.

5.1 Capacitance All capacitors must meet the ± 5% variance

requirement of Section 3.1 measured to an accuracy of better than ± 1% at a frequency of 1 kHz.

5.2 Equivalent Series Inductance The self-resonant frequency from no less than 10% or one capacitor from every lot shall be measured and recorded for design and production verification to meet Section 3.7 requirements.

5.3 Dissipation Factor The dissipation factor from no less than 10% or one capacitor from every lot shall be measured and recorded for design and production verification to meet Section 3.8 and 3.9 requirements. If a frequency other than 1 kHz is used, a calculation should be supplied to verify that the capacitor meets the DF at the operating frequency.

5.4 Hi-pot Test All capacitors shall be hi-potted with terminals

B1,B2,B3,B4 tied together and with respect to terminal BC for 30 seconds per Section 3.4.

All capacitors shall be hi-potted with all terminals tied together and with respect to case for 30 seconds per Section 3.4.

5.5 Leakage Test All capacitors shall have their leakage currents measured with terminals B1,B2,B3,B4 tied together and with respect to terminal BC and meet the requirements of Section 3.5.

All capacitors shall have their leakage currents measured terminals to case and meet the requirements of Section 3.5.

5.6 Terminal to Case Capacitance Test The capacitance to case from no less than 10% or one capacitor from every lot shall have their capacitance to case measured with all terminals tied together and meet the requirements of Section 3.6.

6 SHIPPING REQUIREMENTS

6.1 Test data for all capacitors shipped shall be supplied to Fermilab before shipment for approval.

6.2 Capacitors shall have sufficient packaging to prevent damage during standard shipping practices.

6.3 All capacitors shall have the terminals shorted together to prevent charge buildup.

6.4 Capacitors shall be shipped so that removal of a single panel will allow access to all the capacitor terminals inside the shipping container. This is needed so that capacitor value can be measured without unpacking capacitors.

7 TESTS BY FERMILAB

7.1 100% testing of first articles of capacitance, section 3.1, equivalent series inductance, section 3.7, hipot section 3.4, leakage current, section 3.5 and capacitance to case, section 3.6, mechanical dimensions H, W, L, B, FB, FT and M shown in section 4.2.

7.2 10% sample testing of capacitors from each batch of capacitance, section 3.1, equivalent series inductance, section 3.7, hipot, section 3.4, leakage current, section 3.5 and capacitance to case, section 3.6, mechanical dimensions H, W, L, B, FB, FT and M shown in section 4.2.

8 BID SUBMITTALS

Supplier’s response or detailed calculations required for the following:

a) Dielectric material types

b) Dielectric impregnation type and description

c) Internal termination style (extended foil, staked tab, etc.)

d) Method for estimating lifetime. Absolute numbers may be abstracted by using the operating voltage as a ratio in a table or equation.

e) Estimated equivalent series resistance (ESR) at 25 C and ESR vs temperature

f) Estimated equivalent series inductance (ESL)

g) Outline drawing showing all the requested dimensions from this specification

h) Weight

i) Bushing material, peak voltage, peak current and rms current ratings

j) Typical distribution of capacitance values on a given lot of capacitors

k) General description or outline of quality assurance program

l) Number of similar caps (>1 kVrms; > 1 kJ; AC or resonant operation) the vendor has manufactured in the last 10 years

m) Will all the tests in Section 5 be performed in-house? If not, which elements will be outsourced? Provide detailed test method and equipment model numbers for tests done in Section 5

n) List exceptions to specifications on a separate document as well as alternate suggestions. Include rational for exceptions.

9 HISTORICAL REFERENCES

The following documents were collected for the analysis performed at FNAL.

They are listed only for FNAL reference to aid in future understanding.

Fermi TM-201

Fermi TM-230 Capacitor Banks for Booster Resonant Power Supply, J. Ryk, 1970

Fermi Pub 74-85 Gradient Magnet Power Supply for the Fermilab 8 GeV Proton

Synchrotron

Westinghouse Note AD-10150-CC, Part Number 608B056, 1969

GE Part No. 16L0555TH4, Rev A, E. McGinn 1999

A 3 BeV High Intensity Proton Synchrotron, The Princeton Pennsylvania Accelerator”, CERN Symposium 1956, M.G. White, et al, Booster GMPS Power Supply Resonant Capacitor Specification # 0323–ES–282493

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