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ACCT manual 2-1 - GMW Associates

1. Bergoz Instrumentation Espace Allondon Ouest 01630 Saint Genis Pouilly France Instrumentation Tel 33 450 426 642 Fax 33 450 426 643 A C Current Transformer User s Manual Rev 2 1 WARNING Do NOT heat sensor beyond 80 C 176 F ACCT Electronics are NOT protected against power supply polarity inversion Japan U S A REPIC Corporation GMW Associates 28 3 Kita Otsuka 1 Chome 955 Industrial Road Toshima ku Tokyo 170 0004 San Carlos CA 94070 Tel 03 3918 5326 Tel 650 802 8292 Fax 03 3918 5712 Fax 650 802 8298 sales repic co jp sales gmw com BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Fax 33 450 426 643 email bergoz bergoz com http www bergoz com Registre des M tiers Bourg en Bresse Registre des ing nieurs Zurich TVA VAT IVA USt N FR88414997130 S rl capital 152K Siren 414 997 130 R C S Bourg APE 332B Record of updates Version Release date 2 1 June 5 2008 p 3 p 7 General Description Parts numbers Reference to new High resolution and Wideband versions Output polarity Examples Specifications High resolution version specifications Wideband version specifications BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 1 SUMMARY Page INITALINSPECTION a ass ete naan dulce MARRANT Mage ee rue dites ASSISTANCE
2. Examples ACCT E 10mA HR has 10V output when 10mA pass thru ACCT aperture ACCT E 100mA WB has 1V output when 100mA pass thru ACCT aperture The output voltage is highly linear It features very low measurement noise and excellent dynamic response This makes it an ideal instrument to measure long pulses or pulse trains with resolution down to the micro amp The core is a CoFe amorphous alloy specifically field annealed for this application The ACCT includes active electronics Power supply must be applied to two solder pins and a ground lug High resolution version 15 0 2V and 15 0 2V Wideband version 5 0 1V and 5 0 1V BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 4 ACCT Advantages compared to other CTs The ACCT can measure low AC currents accurately Other current transformers can not do it for the following reasons A passive CT capable of passing 50 60 Hz with less than 1 error must have a 3dB bandwidth down to a few Hertz This imposes a large number of turns typically 500 turns Therefore the sensitivity is in the order of 0 1 V A in a high impedance load If a 10 mA current is measured with this transformer the output is a mere 1mV which cannot be measured on an oscilloscope or voltmeter The situation is not much better at 100 mA current Amplifying the signal from this CT does not help much because the
3. Sat tannins nina RNa athe SERVICE amp RETURN PROCEDURES seen cine taien stete SAFETY INSTRUCTIONS end ne en en GENERAL DESCRIPTION use ennemis ACCT Advantages compared to other CTs OPERATING PRINCIPLES Me SR Ne E Ne ne iERi ELECTRICAL CONNECTIONS sn iion a E Connectors on ACCT sensor with embedded electronics Connectors on ACCT sensor with external electronics OUTPUT SIGNAL POLARITY intense COAXIAL OUTPUT CABLE SELECTION entente distes GAANO IN EE E ne ee pes nr en eee ct ee MECHANICAL DIMENSIONS nier INSTALLATION GENERAL sn Re eee Dette INSTALLATION ON A VACUUM CHAMBER Break in the vacuum chamber electrical continuity Thermal protection of the ACCT nreno iea ne ee ee 10 I CTTOS AS MIRE RE E A Ae eee se a 10 ACCT RADIATION RESISTANCE ccscssssssssssssccssesesscescsseceeescsseceseeees 12 OOO D IN DNA NN EE D D D ND BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 2 INITIAL INSPECTION It is recommended that the shipment be inspected immediately upon delivery If it is damaged in any way contact Bergoz Instrumentation or your local distributor The content of the shipment should be compared to the items listed on the invoice Any discrepancy should be notified to Bergoz Instrumentation or its local distributor immediately
4. Stress absorbent Silicon rubber tape SIR 5 x 105 Gy Silicon rubber SIR 2 x 105 Gy Connector isolation BNC PTFE Teflon lt 103 Gy BNO Polyethylene PE 106 Gy Organic and radiation sensitive materials used in the Rad Hard sensor The Rad Hard sensor is supplied when the Rad Hard option is ordered The ordering code and model number are then terminated by H Component Material Radiation resistance Wiring isolation Polyether ether ketone PEEK 6 x 107 Gy Fiber glass gt 108 Gy with rubber adhesive gt 106 Gy Stress absorbent Polyurethane foam PU 5 x 106 Gy Polyurethane rubber PUR 5 x 106 Gy Connector isolation BNO or BNC Tefzel ETFE 106 Gy The above radiation resistance values are indicative only They do not imply any guarantee of whatever nature from the manufacturer The manufacturer specifically declines any responsibility for any damage direct or consequential caused by ionizing radiations 2 Compilation of Radiation Damage Test Data H Sch nbacher et al CERN 79 04 79 08 82 10 and 89 12
5. AC current gt 20 Arms 20 mA max To be characterized Cannot be ignored when low currents are measured Optional magnetic shield recommended Negligible BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 8 MECHANICAL DIMENSIONS Without magnetic shield ACCT S xxx ID OD H Order code min max max ACCT S 016 16 42 22 ACCT S 028 28 64 22 ACCT S 055 55 91 22 ACCT S 082 82 118 22 ACCT S 122 122 156 22 ACCT S 178 178 226 22 Dimensions en mm With optional magnetic shield MSH gt ACCT S xxx MSH D OD H Weight Order code min max max Kg ACCT S 055 MSH 55 98 102 0 9 ACCT S 075 MSH 75 118 102 1 2 ACCT S 115 MSH 115 158 102 1 7 ID a on al ACCT S 130 MSH 130 175 102 2 0 es ACCT S 175 MSH 175 222 102 2 4 ACCT S 195 MSH 197 250 102 2 6 H axial ACCT S 202 MSH 202 248 102 2 6 ACCT S 245 MSH 245 298 102 3 3 Dimensions en mm In flange ACCT sensors Consult our web site www bergoz com for dimensions BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 9 INSTALLATION GENERAL The metal shield of the ACCT toroid sensor should preferably be isolated from the local ground to prevent a possible ground loop with
6. color coding for proper ACCT polarity COAXIAL OUTPUT CABLE SELECTION Unless specially requested no output coaxial cable is supplied with the ACCT The ACCT output is a baseband signal up to 1 MHz Any industrial grade coaxial cable is suitable In noisy industrial environments a double shielded cable may be required if low currents are measured lt ImA BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Fax 33 450 426 643 A C Current Transformer User s manual Page 7 SPECIFICATIONS Full scale range Connectors Sensor cable Version Output full scale Lower cutoff 3dB Droop Upper cutoff 3dB Risetime Slew rate dV dt Output offset Noise at 10mA F S Noise at 100mA F S Power supply Saturation Primary DC current Ratio accuracy error Destructive level Output current limit Mag field sensitivity Temperature drift Any value from 10mA to 2A factory preset electronics Sensor BNO bipolar BNC Electronics input BNO bipolar BNC Electronics output BNC RG108 recommended up to 100 meters High resolution Wideband 10V 1V 3 Hz 3 Hz lt 2 ms lt 2 ms 300 kHz 1 MHz Slew rate limited 1 5 V us 2 V us 0 2 mV typ 0 2 mV typ 0 5 mV max 0 5 mV max lt 1u Arms lt Su Arms lt Su Arms lt 20y Arms 15Vdc 100mA 5Vdc 100mA External magnetic field 20 Gauss max 1 max lt 0 1 FS DC current Unlimited Spikes gt 100 mC
7. Unless promptly notified Bergoz Instrumentation will not be responsible for such discrepancies WARRANTY Bergoz Instrumentation warrants its beam current monitors to operate within specifications under normal use for a period of 12 months from the date of shipment Spares repairs and replacement parts are warranted for 90 days Products not manufactured by Bergoz Instrumentation are covered solely by the warranty of the original manufacturer In exercising this warranty Bergoz Instrumentation will repair or at its option replace any product returned to Bergoz Instrumentation or its local distributor within the warranty period provided that the warrantor s examination discloses that the product is defective due to workmanship or materials and that the defect has not been caused by misuse neglect accident or abnormal conditions or operations Damages caused by ionizing radiations are specifically excluded from the warranty Bergoz Instrumentation and its local distributors shall not be responsible for any consequential incidental or special damages ASSISTANCE Assistance in installation use or calibration of Bergoz Instrumentation beam current monitors is available from Bergoz Instrumentation 01630 Saint Genis Pouilly France It is recommended to send a detailed description of the problem by fax or email SERVICE PROCEDURE Products requiring maintenance should be returned to Bergoz Instrumentation or its local distributor Bergoz Instr
8. am Current Transformer with DC to 200 MHz range IEEE Trans Nucl Sci NS 16 June 1969 p 934 938 BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 6 ELECTRICAL CONNECTIONS Connectors on the ACCT S sensor and external ACCT E electronics Ordering code EURCHON sr teeta LH Perret he ated tek ASE Output connector type ACCT S ddd Output signals eee BNO 78Q female grounded connector body ACCT S ddd MSH Output signals BNO 78Q female connector body is floating ACCT S ddd 2B Output signals Two BNC 50Q female grounded connector body ACCT S ddd TW Output signals Twisted pair No connector floating winding ACCT E xxxxmA Input signals BNO or 2 BNC or twisted pair matching the sensor O tp tsignal soseri tna AR GR ec AE ee cae BNC female Power supply 5V and SV nn nn stresse Solder pins Power s pply SION ER E Le Lug It is recommended to use a twisted wire cable for the power supply wires Passing the wires thru a common mode choke is advisable OUTPUT SIGNAL POLARITY The A C Current Transformer is bipolar Arrows are printed on the outer surface of the toroid Charges positive crossing the aperture in the direction of the arrow give positive output E g an electron beam passing in the direction of the arrow yields a negative output Note On models with two BNCs or twisted pair outputs conform to the
9. can be made in any conductive metal provided the grounding cable connects properly the the shield It may have the dual purpose of thermal shield and electrostatic shield In this case one should take care that the cooling water pipes do not bring noise to the shield To hold the shield and the ACCT sensor in place while providing good isolation the space between vacuum chamber shield and ACCT sensor can be filled with polyurethane foam If the vacuum chamber requires high temperature bake out fiber glass wool will be preferred Note The ACCT accuracy is not affected by its radial angular or axial position in respect of the beam axis Ferrite cores tubes and beads installed on the coaxial cable contribute significantly to eliminate the noise picked up by the ACCT body via capacitive coupling Avoid ferrite split cores when possible prefer solid cores BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 12 ACCT RADIATION RESISTANCE ACCT S sensor contains materials which may be damaged by ionizing radiations They are listed hereafter Organic and radiation sensitive materials used in the Standard sensor The Standard sensor is supplied when the Rad Hard option is not ordered Component Material Radiation resistance Wiring insulation Polyvinyl chloride PVC 2 x 105 Gy Fiber glass gt 108 Gy with rubber adhesive gt 106 Gy
10. gnetic modulator falls within the bandwidth of the ACCT Depending on the ACCT range this ripple can be unacceptable Typical solutions are e Keep the ACCT and DC sensor away from each other e Install a vertical shield plate between AC and DC sensors Note The ACCT S sensor may need to be protected from external magnetic fields When it is exposed to external magnetic fields higher than ca 20 Gauss it may saturate Break in the vacuum chamber electrical conductivity If the vacuum chamber does not require bake out and the vacuum requirements are moderate a polymer gasket in between two flanges is adequate to assure the desired galvanic isolation If the vacuum chamber needs bake out the most commonly use solution is to braze a section of ceramic on the vacuum chamber tube This is called a ceramic gap The ceramic gap may be installed on centre or off centre of a short pipe section Flanges Ceramic gap BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 10 INSTALLATION ON A VACUUM CHAMBER Cont d Thermal protection of the ACCT The ACCT sensor must not be heated beyond 80 C 176 F If the vacuum chamber requires bake out a thermal shield must be installed between the vacuum chamber or the heating sleeves and the ACCT sensor The thermal shield can be a simple copper cylinder cooled by water circulating in a copper tube b
11. icantly When N is increased L increases with N which is very favourable for the low frequency response But at the same time the sensitivity is decreased by N hence the signal level decreases and becomes too close to the noise floor to make meaningful measurements This is why the ACCT has a moderate number of turns 10 100 depending on the model and instead of increasing L for low frequency response is designed with a very low R load value The active transformer with very low impedance load was first proposed by Hereward in 1960 sees Block diagram on next page BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 5 OPERATING PRINCIPLE Cont d Hereward transformer principle 1960 Output i Primary current To provide the AC response of the first DCCT ever built K Unser in 1969 improved and simplified Hereward s circuit diagram Output Primary current Burden In this circuit the impedance seen by the winding is close to 0 Q because the operational amplifier maintains at all times the voltage difference between its inputs very close to zero The ACCT implements this principle The ACCT incorporates another innovative technique to null the operational amplifier s offset As a result the ACCT output voltage is very close to zero when no primary current flows thru the sensor 1 K B Unser Be
12. noise is amplified as well This is why the ACCT is much superior to other CTs It measures accurately down to 10 mA even down to 1 mA It delivers a strong voltage signal with accuracy better than 1 OPERATING PRINCIPLE The ACCT is a novel instrument to measure low frequency currents from a few Hertz up to hundreds of Kilohertz It is not simply a transformer with an amplified output because such a combination is unable to measure low currents at low frequency The lower frequency cutoff 3 dB of a transformer is given by wo L L fL Where 0 _ _ Where Lis the core winding inductance 2Tt R R is the winding load 2a lt gt ao YS N turns To obtain a low value for f either the value of R must be decreased or the value of L must be increased The inductance L cannot be increased beyond a certain value because physics laws and economics prevent it The inductance is given by L f u S l N Where u is the core alloy relative permeability S is the core magnetic cross section is the magnetic path length core average circumference N is the number of winding turns p is a characteristic of the magnetic alloy and the annealing process The ACCT uses cobalt based alloys specially annealed for this application They feature very high permeability S is limited by the size of the sensor and by economics cobalt is expensive l is imposed by the sensor size N is the only parameter which the designer can vary signif
13. radiations It contains Cobalt msn tn ni nat Up to 0 6 Kg ROMs LR Re a aah teen Up to 0 4 Kg GENERAL DESCRIPTION The A C Current Transformer is specifically designed to measure charged particle beams It measures currents down to 1 mAac With better than 1 accuracy The toroid sensor contains no electronics the electronics is installed in a small external box Their part numbers are e ACCT S ddd for a sensor to be installed in air over the vacuum chamber where ddd is the sensor inner diameter in mm e ACCT S ddd MSH is a sensor in a magnetic shield for installation in air e ACCT CFxx ddd hhh UHV for In flange sensor to be installed in a beam line where xx is the flange outer diameter ddd is the sensor inner diameter in mm hhh is the sensor axial length in mm e ACCT E xxxmA for the external electronics box where xxxmA is the full scale primary current Recent extrnal electronics boxes have an appendix HR for High Resolution version WB for Wideband version e ACCT C xx for the sensor to electronics cable where xx is the cable length in meters Cable is twisted pair RG108 with PVC jacket Maximum cable length is 100 meters Note ACCT is delivered without coaxial output cable The output signal is a high impedance bipolar voltage Output voltage is proportional to current passing thru the ACCT S sensor aperture High resolution version features 10V output full scale Wideband version features 1 V output full scale
14. razed onto the cylinder The water circuit must not pass thru the ACCT aperture It must enter and go out on the same side of the ACCT otherwise it makes a shorting loop around the ACCT toroid Electrostatic shield Electrostatic capacitive coupling between the ACCT body and the vacuum chamber must be avoided This is especially true for high sensitivity ACCTs measuring current at the miliamp level An electrostatic shield may be installed Electrostatic shield z Vacuum chamber ACCT __ Low impedance ground The shield must be grounded on one side only Depending on the cables layout grounding on one side will increase the noise pickup while grounding on the other side will decrease it There is no easy way to predict on which side the electrostatic shield should be grounded Different grounding conditions must be tried until the noise pickup is at its minimum The quality of the grounding thus the efficiency of the shield is determined by the impedance of the grounding scheme In practice its inductance must be minimized Note the noise picked up by capacitive coupling with the vacuum chamber is wideband noise It is best observed with a wideband oscilloscope while the accelerator is running BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 11 INSTALLATION ON A VACUUM CHAMBER Cont d The electrostatic shield
15. the instrument it is connected to From the standpoint of external noise pickup it is advantageous to install the external box ACCT E as close as possible from the ACCT S sensor External noise picked up by the ACCT C cables can often be attenuated by common mode chokes This applies to the coaxial cables and to the power supply twisted wires cable A common mode choke consists of passing the cable up to 7 times thru a ferrite core The ferrite must be selected for its high core loss at the noise frequency to be attenuated INSTALLATION OVER A VACUUM CHAMBER The installation of an A C Current Transformer ACCT on the outside of a vacuum chamber requires some precautions a The electrical conductivity of the vacuum chamber must be interrupted in the vicinity of the ACCT otherwise the wall current will flow thru the ACCT aperture and cancel the beam current b The wall current must be diverted around the ACCT thru a low impedance path c The ACCT must be protected from being heated beyond 80 C 176 F during vacuum chamber bake out d Careful evaluation is required before an ACCT sensor is installed near or under the same shield as a DC transformer with magnetic modulator such as New PCT The leakage field from the magnetic modulator cores typically a few kilohertz will couple with the ACCT core It will result in ripple from the ACCT at the frequency of the DC magnetic modulator Note It happens because the frequency of the ma
16. umentation will repair or replace any product under warranty at no charge The purchaser is only responsible for transportation charges For products in need of repair after the warranty period the customer must provide a purchase order before repairs can be initiated Bergoz Instrumentation can issue fixed price quotations for most repairs However depending on the damage it may be necessary to return the equipment to Bergoz Instrumentation to assess the cost of repair RETURN PROCEDURE All products returned for repair should include a detailed description of the defect or failure name and fax number of the user Contact Bergoz Instrumentation or your local distributor to determine where to return the product Returns must be notified by fax or email prior to shipment Return should be made prepaid Bergoz Instrumentation will not accept freight collect shipment Shipment should be made via Federal Express or United Parcel Service Within Europe the transportation service offered by the Post Offices EMS Chronopost Datapost etc can be used The delivery charges or customs clearance charges arising from the use of other carriers will be charged to the customer BERGOZ Instrumentation A C Current Transformer 01630 Saint Genis Pouilly France User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 3 SAFETY INSTRUCTIONS The instrument designated as A C Current Transformer may become RADIOACTIVE when exposed to ionizing

ACCT manual 2-1 - GMW Associates

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