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15

3.6

Probe Cables

MTII capacitance probes are equipped with special, low-noise coaxial cables. Standard coaxial cables are
not acceptable for connecting the probes to probe amplifier. Cables are available in either 50-ohm or 95-
ohm sizes. Specifications:

Diameter

Operating Temperature

50



Cable

1.95mm (0.076 inch)

-90 to +200ºC (-130 to 390ºF)

95



Cable

1.6mm (0.063 inch)

-90 to +200ºC (-130 to 390ºF)

Table 1: Standard Probe Cable Characteristics

Most probes are shipped with 95

, low noise cables. If cable size is important, please contact the factory.

Cables may be spliced only if the spiced section is 100% shielded. Routing the cable through relays and
other switching devices will interfere with the measurement system.
Cylindrical feed-through assemblies may be used.  Since the cable shield is

not

 at ground potential, the

feed-through  must  have  provisions  that  guarantee  that  the  cable  shield  will  be isolated. This  is  typically
accomplished by selecting a triaxial feed-through, utilizing the center and middle conductors and allowing
the  outside  conductor  to  ground  with  the  equipment. When  selecting  a  triaxial  feed-through,  it  is  also
important that the center conductor (tip) of remain 100% shielded by the middle (fringe guard conductor).
Contact the factory for information on MTII-manufactured feed-through assemblies.

3.7

Target Grounding

The  target  being  measured  by  the  probes  connected  to  the Accumeasure™  9000  must  be  grounded
directly to the board power supply grounds for the probe to target gap to be accurately measured.

In general, it is recommended that grounding practices for sensitive equipment be applied when using the
Accumeasure

TM

  amplifier.  For  additional  information  on  grounding  practices  refer  to  H.W.  Ott’s

Noise

Reduction Techniques in Electronic Systems

 (John Wiley and Sons, 1976) or to Chapter 24 of the

Analog

Devices Applications Reference Manual

 (1993).

3.8

Static Electric Discharge Precaution

The  face  of  the  probe  and  the  center  conductor  of  the  BNC  for  probe  input  is  static
sensitive.    Due  to  the  nature  of  capacitance  amplifiers  it  is  possible  to  damage  the
sensitive input circuitry if there is a static electric discharge into the center conductor of
the probe input BNC or the center sensing area of the probe itself.  Protection circuitry
has  been  incorporated  to  minimize  this  effect  but  a  discharge  of  sufficient  amplitude
will cause damage.  The probes may be handled without ground straps, but high static
charges on the target may arc over to the probe.

!

NOTE

A  poor  ground  return  and  the  connection  of  the  board output  connectors  to  equipment  such  as
oscilloscopes, chart recorders, or data loggers can create ground loops, which will cause errors due to
excessive of 50-60 Hz noise on the carrier and gap output signals.

Содержание AccuMeasure 9000

Страница 1: ...013 AccuMeasure 9000 Capacitance Sensor Amplifier Users Manual MTI Instruments Incorporated 325 Washington Avenue Extension Albany New York 12205 USA Phone 518 218 2550 or 800 342 2203 USA Only Fax 51...

Страница 2: ...This page was intentionally left blank...

Страница 3: ...i Revision History Rev 4 0 Release...

Страница 4: ...vided and upon the expiration of the warranty period of all such a liability shall terminate The foregoing shall constitute the exclusive remedy of the purchaser and the exclusive liability of the Sel...

Страница 5: ...al is written in an official language of the Member State Contact MTI Instruments for the availability of translated manuals WARNING ELECTRICAL SHOCK ELECTROCUTION HAZARD This equipment is connected t...

Страница 6: ...RN SHIPMENT PROCEDURE 5 2 OPERATING PRINCIPLES 6 3 INSTALLATION INSTRUCTIONS 8 3 1 POWER REQUIREMENTS 8 3 2 CONNECTIONS 9 3 3 CONTROL SWITCHES 13 3 4 DISPLAYS 13 3 5 PROBE MOUNTING 14 3 6 PROBE CABLES...

Страница 7: ...parasitic capacitance and ensure the highest linearity Front panel gain and offset controls permit minor adjustments of the probe calibration characteristics An internal 5 pole Butterworth low pass f...

Страница 8: ...to 40 C 40 to 100 F Storage Temperature 15 to 65 C 5 to 150 F Dimensions LxWxH 241x165x56mm 9 5x6 5x2 2 Mass 2 3kg 5lbs Probe Voltage 8 5Vrms Max Bargraph Proportional to gap 10 of range per bar 1 Al...

Страница 9: ...Cryogenic and Vacuum compatible probes are available Contact the factory Accuracy 0 05 of range when calibrated to a known standard Probe Cable Interchangeability Accurate within 0 5 of range without...

Страница 10: ...r optional digital panel meter s should be illuminated Without a probe cable s attached to the probe connector on the front panel all of the bargraph display segments should be fully illuminated Instr...

Страница 11: ...al shipping carton if available and forward prepaid to MTI Instruments Inc Supervisor of Manufacturing 325 Washington Avenue Extension Albany NY 12205 5505 Mark RMA and the RMA number if a number is i...

Страница 12: ...on the principle of parallel plate capacitor measurement The electrical capacitance formed between an Accumeasure TM probe and a target surface varies as a function of the distance gap between these...

Страница 13: ...C voltage that is linearly proportional to the average value of the probe gap impedance and an AC voltage variation from the DC voltage that is directly proportional to the amplitude of the target vib...

Страница 14: ...1 Remove the power cord from the rear panel power receptacle 2 Pry up one end of the power receptacle cover by inserting the blade of a small screwdriver under the tab next to the CORCOM lettering 3...

Страница 15: ...ding post labeled GROUND on the rear panel see Figure 7 Accumeasure 9000 1 Rear Panel or The displacement voltage output signal s is available from the BNC connector s labeled 1 2 and SUM on the rear...

Страница 16: ...fset Switch Indicator Offset Adjustment Probe Input Offset Switch Indicator Offset Adjustment Digital Display Power Indicator Gain Adjustment Figure 3 Accumeasure 9000 1 Front Panel Digital Display Fi...

Страница 17: ...2 Gain Adjustment Channel 1 Bargraph Display Channel 1 Offset Switch Indicator Channel 2 Offset Switch Indicator Probe Input Channel 1 Probe Input Channel 2 Channel 2 Offset Adjustment Channel 2 Digi...

Страница 18: ...ignal Output 20 W 50 60 Hz 1 100 240 VAC T 0 4A 250V Signal Output Signal Output Ground Connection Power Cable Connection Fuse On Off Switch Signal Output 2 1 20 W T 0 4A 250V 100 240 VAC 50 60 Hz SUM...

Страница 19: ...see 4 1 Probe Amplifier Calibration Check The external offset potentiometer is dis engaged when the switch is set to its out position The control is engaged for offset adjustment when the switch set...

Страница 20: ...e probe face parallel to the target surface Probe tilt causes measurement errors so a tilt of less than 5 of range is recommended That would mean that for a 500um 20 mil range sensor the edge of the s...

Страница 21: ...manufactured feed through assemblies 3 7 Target Grounding The target being measured by the probes connected to the Accumeasure 9000 must be grounded directly to the board power supply grounds for the...

Страница 22: ...nge Gain is adjusted at 100 of range Use the following procedure 1 Set the voltmeter to monitor the output of the amplifier 2 With the unit turned off adjust the probe so it is lightly touching the ta...

Страница 23: ...n air gap equal to the maximum probe range value for the probe provided with the system The full range value is a function of the probe used and the zero voltage gap value For example a 20 mil range p...

Страница 24: ...ush that can be achieved and this is dependant on several factors including probe type and cable length The maximum push recommended is 40X When employing pushed amplifier and probe combinations the o...

Страница 25: ...0 volts 8 Connect the DVM or oscilloscope to the Channel 2 output and repeat steps 6 and 7 for Channel 2 output 9 Connect the DVM or oscilloscope to the sum signal output on the rear panel It should...

Страница 26: ...00 it should be returned to the factory for servicing Before following the troubleshooting procedure 1 Set up a probe and grounded target so that probe to target gap is within the probe full scale ran...

Страница 27: ...ield to center short circuit and probe for interelectrode short circuits 2 If jumper changes on the probe amplifier board have been performed since the unit has been received from MTI contact MTI to r...

Страница 28: ...ighted 1 Check the probe cable connection to the front panel ensure that the cable is securely attached to the receptacle 2 Check for an open circuit in the center wire of the probe cable 3 Check for...

Страница 29: ...probe support fixture to ensure the probe and the fixture are not loose 2 Check the shield on the sensor cable and the connectors in the sensor cable signal path for 100 shield integrity and connector...

Страница 30: ...FROM MTI INSTRUMENTS 1510A Battery Powered Signal Simulator Generator Proforma 300 Semiconductor Wafer Qualification and General Thickness measurement Capacitance MicroTrak Laser Triangulation Displa...

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Страница 32: ......

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