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MKS Baratron 127A Скачать руководство пользователя страница 25

Chapter Three: Overview

Circuit Description

17

Chapter Three: Overview

Circuit Description

The variable capacitance sensor consists of rigidly attached capacitive electrodes located on the
back or reference side of a metal diaphragm. The reference side is permanently evacuated and
sealed thus making the pressure measurement totally independent of the gas type or composition.
When pressure is applied to the diaphragm, its deflection produces a change in the distance
between the electrodes and diaphragm and a resultant capacitance change.

The center electrode increases its capacity at a greater rate than does the outer concentric
electrode. This imbalance of capacities caused by pressure is converted to a small DC Voltage in
the first stage diode bridge. This bridge is excited by a precision constant frequency oscillator.
The resultant signal is linearized, zeroed and amplified to produce a precise 0 to 10 VDC signal
scaled to the range of the sensor.

To produce the fine zero and span stability that this transducer possesses, the sensor and bridge
electronics are temperature controlled. This thermal enclosure will reduce the effects of ambient
temperature changes by a factor of at least 35 (that is, 35

°

C change in ambient will produce 1

°

C

change inside the thermal housing).

Sensor

Diode

Bridge

Heater

Supply

Oscillator

DC

Amplifier

Pressure

CAP

CAP

Heated Enclosure

+15 VDC Input

0 - 10 VDC

Output

Figure 6: Block Diagram of the Circuitry

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Содержание Baratron 127A

Страница 1: ...nstruction Manual MKS Baratron Type 127A and Type 128A Absolute Pressure Transducers Six Shattuck Road Andover MA 01810 2449 800 227 8766 or 978 975 2350 Fax 978 975 0093 E mail mks mksinst com Web site http www mksinst com ...

Страница 2: ...rchaser before returning any equipment covered by this warranty which is asserted to be defective by the purchaser shall make specific written arrangements with respect to the responsibility for shipping the equipment and handling any other incidental charges with the MKS sales representative or distributor from which the equipment was purchased or in the case of a direct purchase from MKS with th...

Страница 3: ...110660 P1 Rev E 6 97 MKS Baratron Type 127A and Type 128A Absolute Pressure Transducers ...

Страница 4: ...ng photocopying and recording or by any information storage or retrieval system except as may be expressly permitted in writing by MKS Instruments Inc Baratron is a registered trademark of MKS Instruments Inc Andover MA Inconel is a registered trademark of Inco Alloys International Inc Huntington WV Cajon VCR and VCO are registered trademarks of Cajon Company Macedonia OH ...

Страница 5: ...Unpack the Type 127 128 Unit 9 Unpacking Checklist 9 Interface Cables 10 Generic Shielded Cable Description 11 Example 1 Preferred Method To Connect Cable 12 Example 2 Alternate Method To Connect Cable 12 Product Location and Requirements 13 Operating Environmental Requirements 13 Setup 13 Dimensions 14 Electrical Information 15 Connector 16 Chapter Three Overview 17 Circuit Description 17 Labels ...

Страница 6: ...Unit 21 Appendix A Product Specifications 23 Type 127 Performance Specifications 23 Type 127 Physical Specifications 24 Type 128 Performance Specifications 25 Type 128 Physical Specifications 26 Appendix B Model Code Explanation 27 Model Code 27 Index 29 ...

Страница 7: ...e 127 128 Transducer 14 Figure 4 Dimensions of a High Range Type 127 128 Transducer 14 Figure 5 Top View of a Type 127 128 Transducer 15 Figure 6 Block Diagram of the Circuitry 17 Figure 7 Serial Number Label 18 Tables Table 1 Definition of Symbols Found on the Unit 2 Table 2 Pinout of the Interface Connector 16 Table 3 Maximum Pressure Reading for Zero Adjustment 19 Table 4 Lowest Suggested Press...

Страница 8: ...List of Figures and Tables vi ...

Страница 9: ...ce condition or the like which if not correctly performed or adhered to could result in injury to personnel Caution The CAUTION sign denotes a hazard It calls attention to an operating procedure practice or the like which if not correctly performed or adhered to could result in damage to or destruction of all or part of the product Note The NOTE sign denotes important information It calls attentio...

Страница 10: ...IEC 417 No 5019 Frame or chassis IEC 417 No 5020 Equipotentiality IEC 417 No 5021 Direct current IEC 417 No 5031 Alternating current IEC 417 No 5032 Both direct and alternating current IEC 417 No 5033 a Class ll equipment IEC 417 No 5172 a Three phase alternating current IEC 617 2 No 020206 Caution refer to accompanying documents ISO 3864 No B 3 1 Caution risk of electric shock ISO 3864 No B 3 6 C...

Страница 11: ...de by qualified service personnel only USE CAUTION WHEN OPERATING WITH HAZARDOUS MATERIALS If hazardous materials are used users must take responsibility to observe the proper safety precautions completely purge the instrument when necessary and ensure that the material used is compatible with the materials in this product including any sealing materials PURGE THE INSTRUMENT After installing the u...

Страница 12: ...rated maximum pressure refer to the product specifications for the maximum allowable pressure INSTALL A SUITABLE BURST DISC When operating from a pressurized gas source a suitable burst disc should be installed in the vacuum system to prevent system explosion should the system pressure rise KEEP THE UNIT FREE OF CONTAMINANTS Do not allow contaminants of any kind to enter the unit before or during ...

Страница 13: ...bient or process temperature variations typically encountered in process line environments The 127 transducer has the sensor temperature controlled at 45 C the 128 transducer has the sensor temperature controlled at 100 C RFI shielding is standard to prevent interference from RF or noisy electrical environments Both units comply with the European EMC Directive 89 336 EEC which governs electromagne...

Страница 14: ...n this chapter introduces the product and describes the organization of the manual Chapter Two Installation explains the environmental requirements and describes how to mount the instrument in your system Chapter Three Overview gives a brief description of the instrument and its functionality Chapter Four Operation describes how to use the instrument and explains all the functions and features Cha...

Страница 15: ...the use of your Type 127 128 instrument or to obtain information about companion products MKS offers contact any authorized MKS Calibration and Service Center If it is necessary to return the instrument to MKS please obtain an ERA Number Equipment Return Authorization Number from the MKS Calibration and Service Center before shipping The ERA Number expedites handling and ensures proper servicing o...

Страница 16: ...Customer Support Chapter One General Information 8 This page intentionally left blank ...

Страница 17: ...ved safely If you find any damage notify your carrier and MKS immediately If it is necessary to return the unit to MKS obtain an ERA Number Equipment Return Authorization Number from the MKS Service Center before shipping Please refer to the inside of the back cover of this manual for a list of MKS Calibration and Service Centers Unpacking Checklist Standard Equipment Type 127 or Type 128 Unit Typ...

Страница 18: ...raided shielded cable properly grounded at both ends is required during use No additional installation requirements are necessary to ensure compliance with Directives 92 59 EEC and 73 23 EEC MKS offers a full line of cables for all MKS equipment Note 1 An overall metal braided shielded cable properly grounded at both ends is required during use to meet CE specifications 2 To order a metal braided ...

Страница 19: ...s with flying leads at one or both ends it is important at each such end to ground the shield before the wires exit Make this ground with absolute minimum length Refer to Figures 1 and 2 page 12 A inch piece of 22 wire may be undesirably long since it has approximately 5 nH of inductance equivalent to 31 ohms at 1000 MHz After picking up the braid s ground keep wires and braid flat against the cas...

Страница 20: ...tional Plastic or Metal Cable Clamp For Physical Strain Relief Figure 1 Preferred Method To Connect an Overall Metal Braided Shielded Cable Example 2 Alternate Method To Connect Cable shown on a transducer Transducer Overall Insulation if present Braid Strands Twisted Under Washer Keep Wires Flat Against Case Optional Plastic or Metal Cable Clamp For Physical Strain Relief Screw Split Lock Washer ...

Страница 21: ...ing the pressure port will fall away from the diaphragm thereby not affecting the measurement It is important that the unit be kept free from vibration as the diaphragm when not subject to gas damping at low pressure may become susceptible to resonance The 0 1 and 1 Torr Full Scale units are the most sensitive and any vibration that exists should be isolated from the unit by the use of sponge rubb...

Страница 22: ...03408 Input 15 VDC Range 1 TORR Output 0 10 VDC M KS Instrum ents Inc Made in the USA Figure 3 Dimensions of a Low Range Type 127 128 Transducer 1 31 33 3 3 74 95 0 0 19 4 7 3 00 76 2 diameter 127AA 0001B Serial Model 000103408 Input 15 V DC Ra n ge 1 TO RR Ou tpu t 0 10 VDC MKS Instruments Inc Made in the USA 1 12 28 4 Cajon 8 VCR or equivalent for high range units Figure 4 Dimensions of a High R...

Страница 23: ...capable of supplying 15 VDC 5 at 250 mA minimum The Type 128 transducer requires 500 mA Noise and ripple should be less than 20 mV peak to peak Any readout device may be used which has input capabilities of 0 to 10 VDC and impedance greater than 10k ohms Note The ground of any external power supply and readout should be the same as the sensor ground chassis ground to minimize any possible ground l...

Страница 24: ...inout of the Interface Connector Pin Number Assignment 1 No Connection 2 Pressure Output 3 No Connection 4 No Connection 5 15V Return 6 15 VDC 7 15 VDC 8 No Connection 9 No Connection 10 No Connection 11 No Connection 12 Output Return 13 No Connection 14 No Connection 15 Chassis Ground Table 2 Pinout of the Interface Connector Note The No Connection pin assignment refers to a pin with no internal ...

Страница 25: ...r concentric electrode This imbalance of capacities caused by pressure is converted to a small DC Voltage in the first stage diode bridge This bridge is excited by a precision constant frequency oscillator The resultant signal is linearized zeroed and amplified to produce a precise 0 to 10 VDC signal scaled to the range of the sensor To produce the fine zero and span stability that this transducer...

Страница 26: ...ull scale range and input and output signal information The label also displays the CE symbol indicating that the 127 128 transducer meets the requirements of the European Community s EMC Directive 89 336 EEC 127AA 0001B Serial Model 000103408 Input 15 VDC Range 1 TORR Output 0 10 VDC MKS Instruments Inc Made in the USA Figure 7 Serial Number Label ...

Страница 27: ...rr range Table 3 page 19 lists the maximum pressure for each full scale range 2 Adjust the zero by turning the Zero potentiometer located on the top of the unit Refer to Figure 5 page 15 for the location of the Zero pot The zero adjustment may also be made at the front panel of an MKS supplied readout power supply unit if used Maximum Pressure Reading for Zero Adjustment Full Scale Range Maximum P...

Страница 28: ... 2 5 Torr 10 000 Torr 5 Torr 15 000 Torr 7 5 Torr 20 000 Torr 10 Torr 25 000 Torr 12 5 Torr Table 4 Lowest Suggested Pressure Reading Lowest Suggested Pressure for Control Full Scale Range Lowest Pressure Reading 0 1 Torr 5 x 10 4 Torr 1 Torr 5 x 10 3 Torr 2 Torr 1 x 10 2 Torr 10 Torr 5 x 10 2 Torr 100 Torr 5 x 10 1 Torr 1000 Torr 5 Torr 5000 Torr 25 Torr 10 000 Torr 50 Torr 15 000 Torr 75 Torr 20...

Страница 29: ...pt to repair the transducer signal conditioner electronics since replacement or movement of PC board components may require complete recalibration of the unit Zero Check The only maintenance task required is a periodic zero adjustment Refer to How To Zero the Type 127 128 Transducer page 19 for instructions on zeroing the transducer How To Clean the Unit Periodically wipe down the unit with a damp...

Страница 30: ...General Information Chapter Five Maintenance 22 This page intentionally left blank ...

Страница 31: ...15 of Reading temperature coefficient 0 12 of Reading temperature coefficient CE Compliance Electromagnetic Compatibility1 EMC Directive 89 336 EEC Resolution 0 01 of Full Scale Response Time 16 milliseconds Temperature Coefficient Zero 0 1 Torr 1 Torr to 25K Torr Span 0 015 F S C 0 005 F S C over 15 to 40 C 0 02 Reading C over 15 to 40 C 1 An overall metal braided shielded cable properly grounded...

Страница 32: ...t Power at startup after 1 hour at 30 C 15 VDC 5 250 mA 150 mA Internal Volume 7 0 cc Material Exposed to Gas Inconel plus pressure fitting materials if applicable Output Signal 0 to 10 VDC into 10K ohm load or greater Overpressure 1 Torr to 25K Torr 0 1 Torr 35 psia 20 psia or 120 F S whichever is greater Temperature ambient operating sensor operating 15 to 40 C 45 C Weight 1 kg 2 25 lbs Due to c...

Страница 33: ...Reading temperature coefficient CE Compliance Electromagnetic Compatibility2 EMC Directive 89 336 EEC Resolution 0 01 of Full Scale Response Time 16 milliseconds Temperature Coefficient Zero 0 1 Torr 1 Torr to 25K Torr Span 0 015 F S C 0 005 F S C over 20 to 70 C 0 02 Reading C over 20 to 70 C 2 An overall metal braided shielded cable properly grounded at both ends is required during use ...

Страница 34: ...Input Power at startup 15 VDC 5 500 mA Internal Volume 7 0 cc Material Exposed to Gas Inconel plus pressure fitting materials if applicable Output Signal 0 to 10 VDC into 10K ohm load or greater Overpressure 1 Torr to 25K Torr 0 1 Torr 35 psia 20 psia or 120 F S whichever is greater Temperature ambient operating sensor operating 20 to 70 C 100 C Weight 1 kg 2 25 lbs Due to continuing research and ...

Страница 35: ... Code The options of your transducer are identified in the model code when you order the unit The model code is identified as follows 12XAYYYYYZ where Type Number Full Scale Range XXXXX Z 12XA Fitting Type Number 12XA This designates the model number of the instrument either 127A or 128A ...

Страница 36: ... Full Scale Range Ordering Code 0 1 000 1 1 00001 2 00002 10 00010 100 00100 1 000 01000 5 000 05000 10 000 10000 15 000 15000 20 000 20000 25 000 25000 Fittings YY The type of fittings is designated by a single letter code Fittings Ordering Code tube A Cajon 8 VCR female B Mini CF rotatable C NW 16 KF D Cajon 8 VCO female E ...

Страница 37: ...scale range 5 24 26 G Grounding 15 I Interface cable 10 Interface connector 16 Isolation valve 5 L Labels 2 18 M Maintenance 21 Manual organization 6 Model code 27 Mounting 13 O Overpressure 5 P Pressure control 20 reading 20 zero 19 R Range 28 Returning the product 7 9 S Safety information 1 4 Setup 13 Symbols 2 T Temperature ambient operating 13 24 26 sensor operating 5 24 26 ...

Страница 38: ...Index 30 V Vibration 13 W Wetted material 5 24 26 Z Zero 13 19 21 ...

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