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KYOWA DPM-900A Series Instruction Manual

Dynamic strain amplifier
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DYNAMIC STRAIN AMPLIFIER
Thank you for purchasing KYOWA's product DPM-900A series Dynamic
Strain Amplifier.
Read this Instruction Manual carefully in order to make full use of the high
performance capabilities of the product.
Do not use the product in methods other than described in this Manual.
Copyright © KYOWA ELECTRONIC INSTRUMENTS CO., LTD. All rights reserved.
This Instruction Manual may not be copied or reproduced, in whole or part, without consent of KYOWA.
Generally, company names and trade names described in this Instruction Manual are trademarks or
registered trademarks of the companies.
The contents of the Instruction Manual are subjected to change without prior notice.
DPM-900A SERIES
INSTRUCTION MANUAL
IM-A-736 September 2009

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Summary of Contents for KYOWA DPM-900A Series

  • Page 1 Copyright © KYOWA ELECTRONIC INSTRUMENTS CO., LTD. All rights reserved. This Instruction Manual may not be copied or reproduced, in whole or part, without consent of KYOWA. Generally, company names and trade names described in this Instruction Manual are trademarks or registered trademarks of the companies.
  • Page 2 CONTENTS STANDARD ACCESSORIES ........................1 SAFETY PRECAUTIONS ..........................1 PRIOR TO USE............................1 SAFETY SYMBOLS ........................... 1 NOTATION USED IN THE INSTRUCTION MANUAL ................4 Informational Notes............................. 4 Examples of Notations..........................4 1. PRODUCT OUTLINE ..........................5 1-1 PRODUCT OUTLINE.......................... 5 1-2 SYSTEM CONFIGURATION......................
  • Page 3 6-5-1 Functions of Exclusive Carrying Case ..................32 6-5-2 Carrier Synchronization between Exclusive Carrying Cases ..........32 7. TROUBLE SHOOTING........................... 33 7-1 DPM-900A SERIES CANNOT BE TURNED ON ................33 7-2 INITIAL BALANCING IS IMPOSSIBLE ..................33 7-3 NO OUTPUT IS AVAILABLE ......................34 7-4 UNSTABILITY OF THE ZERO POINT ..................
  • Page 4 Or, failure of the DPM-900A series may result. PRIOR TO USE For safe use of the DPM-900A series, do not forget to read the “Safety Precautions” prior to use. Kyowa Electronic Instruments Co., Ltd. assumes no liability for any damages resulting from user’s failure to comply with the safety precautions.
  • Page 5 To prevent an electric shock hazard, be sure to ensure protective ground before connecting the power cable. If 3P-2P conversion adapter is used, be sure to ground the DPM-900A series to the “GND” terminal. If a 2p flat vinyl power code is used, always ground with optional grounding conductor.
  • Page 6 ● Do not use the DPM-900A series under poor power condition. When using the AC power cable, use the DPM-900A series with 90 to 110 VAC, 50/60 Hz. Use the DPM-900A series in an environment without instantaneous voltage drop or interfering noise.
  • Page 7 Informational Notes Certain notations are used as necessary to attract your attention to information that requires special care when handling the DPM-900A series and to information provided for reference purpose. Examples of Notations NOTE Essential precautions required when handling the DPM-900A series.
  • Page 8 1. PRODUCT OUTLINE 1-1 PRODUCT OUTLINE The DPM-900A series is a strain amplifier that incorporates an AC excitation voltage. When compared to a DC type strain amplifier, the DPM-900A series generally marks high stability, sensitivity and lower noise. In addition to these, the DPM-900A series provides unique features as follows.
  • Page 9 This allows connection of the DPM-900A series directly to a recorder or a voltmeter. To measure a strain converted in electric signals, a calibration signal is used. The DPM-900A series uses a calibration signal that has been certified through a standardizing equipment KYOWA maintains.
  • Page 10 SET switch Set the VOLTAGE OUT and CAL switches. Press the SET switch twice to set the internal gain of the DPM-900A series. CAL ON switch +: Adds + calibration signal that is set to the CAL ON switch to the output.
  • Page 11 NOTE Internal gain: Gain from the input to the output of the DPM-900A series. Capable of setting the internal gain within ×200 to ×20000. In addition, when the internal gain is high, it means high sensitivity and when it is low, low...
  • Page 12 For details of the setting method, see “5-11 OSC SYNCHRONIZATION” and “5-14 EXCITATION VOLTAGE.” Centralized connector For connecting the power cable in general. ⑦ When the DPM-900A series are housed in the carrying case, it enables to connect them with certain control signals.
  • Page 13 Output instrument is a voltmeter with input impedance 5 kΩ or more or recorder. Requires for reading the amplified strain signal. The DPM-900A series is provided with a digital panel meter which lets you voltmeter its out. Connect the output instrument to the DPM-900A series using the output cable, and accessory.
  • Page 14 3-3 INITIAL SETTING Set all setting switches 1 to 4 to OFF. MEMO Note that setting switch 1 is not necessarily to set to OFF when operating multiple DPM-900A series Setting Switch at a time. Read “5-11 OSC SYNCHRONOUS.” NOTE...
  • Page 15 4. BASIC OPERATION This chapter describes the basic operation of the DPM-900A series. The instructions given in this chapter is related to the usage of a single unit. MEMO For operation of multiple channels using the exclusive carrying case, see “6-5 EXCLUSIVE ...
  • Page 16 900A series become measuring state. NOTE After turning ON the power, be sure to bridge check the DPM-900A series before measurement. For details, see “5-4 BRIDGE CHECK.” appears after illumination of all LEDs, it is the indication of abnormality that has occurs to the control program.
  • Page 17 4-4 SELECTING MODE The DPM-900A series provides “Normal Mode”, “TEDS Mode” and “ACTL LOAD Mode.” Setting methods of the internal gain and display unit of the indication varies with every mode. Every time the TEDS and ACTL LOAD switches are pressed and hold, the switches light up and out.
  • Page 18 After setting the internal gain, ○○○ appears without appearing to the monitor, read “9-4 TROUBLESHOOTING.” After connecting or changing the sensor, be sure to bridge check the DPM-900A series before setting the internal gain. Set the VOLTAGE OUT switch from 1.00 to 10.00. MEMO The rated capacity and rated output of the strain-gage transducer are found in its Test Data Sheet.
  • Page 19 ×1 to ×1/2.5. NOTE The internal setting range of the DPM-900A series is ×200 to ×20000. For details, see “5-7 INTERNAL GAIN.” Capable of adjusting the internal gain within the range of ×80 to ×20000 by conducting the sensitivity fine adjustment.
  • Page 20 However, the sensitivity at that time is not guaranteed. The maximum output of the DPM-900A series is ±10 V. Where a large amount of strain is input and exceeds the allowable range of the maximum output, the indication on the panel meter blinks.
  • Page 21 5-4 BRIDGE CHECK The DPM-900A series provides a bridge-check function. This function is used to check cable breaking on the whole input system, including the input cable and connector. Press and hold the BAL switch to conduct the bridge check.
  • Page 22 CONTROL.” NOTE The CPU controls to minimize remaining voltage during balancing the DPM-900A series. If one time of balancing is not enough, repeat balancing a few times. In that case, one time of balancing may require up to 5 seconds, but this does not reflect any error.
  • Page 23 When the measuring target is strain gage Follows are the setting procedures of the optimum internal gain. 1) Set the DPM-900A series to the normal mode. (When the TEDS or ACTL LOAD switch is lightning up, press and hold the either switch to light out.
  • Page 24 Suppose when using the strain gage transducer with the rated output 1567 µV/V and gage factor 2.00. Follows are the setting procedures of the optimum internal gain. 1) Set the DPM-900A series to the normal mode. (When the TEDS or ACTL LOAD switch is lightening up, press and hold the either switch to light out.) 2) Connect the strain gage transducer and conduct bridge check.
  • Page 25 ACTL LOAD for more accurate measurement. Follows are the setting procedures of the optimum internal gain with the ACTL LOAD. 1) Set the DPM-900A series to the ACTL LOAD mode. (Press and hold the ACTL LOAD switch to lights up.) 2) Connect the strain gage, strain gage transducer, or external calibrator to the input and conduct bridge check.
  • Page 26 For details, see “5-13 REMOTE CONTROL.” 5-10 KEY-LOCK The DPM-900A series provides key-lock function. Use the key-lock function in order to prevent the measuring parameters from changing when the keys are touched by mistake. (Setting methods other than POWER switch become invalid. However, the setting values of the CAL and VOLTAGE OUT switches are changeable.)
  • Page 27 The YB-500 series exclusive carrying case (option) achieves automatic connection of all OSC terminals internally. So it is a great convenience. 3) Set the setting switch 1 of the DPM-900A series to ON (MANU) and setting switch 2 to OFF (INT) which is to be the master.
  • Page 28 5-12 APPLICATION OF CENTRALIZED CONNECTOR The DPM-900A series provides a centralized connector on its rear panel. Generally, the connector is used to connect with an AC power supply via the accessory power cable. The connector also provides a pin that connects with a DC power supply.
  • Page 29 5-13-1 Remote Control Signals Control signal input circuit is shown at the right. 10kΩ HC14 Remote Control Signal Input COM (Pin No.5) Control signals are valid when they are on the “L” (0 V) level. While this level is maintained, functions are executed.
  • Page 30 5-13-2 External Connection When remote controlling the DPM-900A series, use the terminals of the centralized connector. Perform wiring after removing the housing from the centralized connector. For details of the centralized connector, see “5-12 APPLICATION OF THE CENTRALIZED CONNECTOR.” NOTE An AC power supply is also connected to the centralized connector.
  • Page 31 3. Setting Switch When the BV 0.5 V lamp on the front panel lights up, the DPM-900A series is set to 0.5 Vrms, when the light lights out, 2 Vrms. NOTE Be sure to balance every time an excitation voltage has been switched from one to the other.
  • Page 32 6. OPTIONS This chapter describes all options that can be used together with the DPM-900A series. These options are available for separate purchasing. 6-1 BRIDGE BOX The bridge box can be conveniently used for measuring strains with strain gages. The bridge box incorporates highly stable resistors to allow a variety of strain gage bridges.
  • Page 33 6-1-3 Wiring to Bridge Box How to configure a variety of strain gage bridges is described below. Wiring to the bridge box Bridge Circuit Gage Method Quarter bridge method (2-wire system) Quarter bridge method (3-wire system) Half bridge method Half bridge method (3-wire active-active system) Full bridge method...
  • Page 34 6-2 AMPLIFIER STAND FA-1B When operating a single unit of the DPM-900A series, this rubber made stand is used for fixing. 6-3 EXTENSION CABLE N For connecting the bridge box or strain gage transducers at a remote place. The cable ends are provided with connectors.
  • Page 35 But there is no problem in performance. • While turning ON (1 hour or more after turning ON the power) and immediately after the turning ON, the main body of the DPM-900A series housed in the exclusive carrying case is hot.
  • Page 36 7. TROUBLE SHOOTING If the DPM-900A series does not operate as expected or if its operation is unstable, do not take it as a machine trouble right away but make sure whether or not the operating environment is acting as the cause.
  • Page 37 Press the V ADJ. switch to execute the zero point adjustment so as to obtain an output voltage of zero. Contact KYOWA or our representatives if the trouble still remains after carrying out the proper remedy. 7-3 NO OUTPUT IS AVAILABLE ♦...
  • Page 38 This interference occurs when a measuring object has a certain electric potential, AC or DC. In this case, grounding the DPM-900A series does not necessarily bring about a good result, but connection of a measuring object to the DPM-900A series can be the solution in some cases.
  • Page 39 8. SPECIFICATIONS 8-1 SPECIFICATIONS DPM-911A DPM-912A Measuring Target Strain Gage, Strain Gage Transducer Measuring CH 1 CH/unit Applicable Bridge Resistance 60 Ω to 1000 Ω Gage Factor 2.00 fixed Bridge Power 2 V rms, 0.5 V rms selectable Voltage Frequency 5 kHz sine wave 12 kHz sine wave Balancing Range...
  • Page 40 DPM-911A DPM-912A S/N Ratio 54 dBp-p or more 52 dBp-p or more RTI: Within 2 µm/mp-p RTI: Within 2.5µm/mp-p [when 500 µm/m is input, outputs [when 500 µm/m is input, outputs 10.00 V.] 10.00 V.] 60 dBp-p or more 57 dBp-p or more [when 1000 µm/m is input, [when 1000 µm/m is input, outputs 10.00 V.]...
  • Page 41 8-2 BLOCK DIAGRAM AND OPERATION PRINCIPLE 8-2-1 Block Diagram 8-2-2 Operation Principle We explain it as follows depending on the above block diagram. Changes in physical quantities are detected as changes in resistance of strain gages and converted in electric signals. As the result, the strain gage bridges output minute AC volts.
  • Page 42 • The practical frequency of carrier wave is 30 kHz or thereabouts. High response is therefore unavoidable. • Easily affected by resistance induced by wirings. From the above, the DPM-900A series is optimum for such strain measurements as follows. (1) General strain measurements using strain gages. (2) Measurements that requires high stability.
  • Page 43 In addition, if a side of the bridge is broken, an error indication does not necessarily agree with its location. Wire-breaking locations Error None NOTE appears, it indicated that the bridge check circuit is faulty. In this case, contact KYOWA or our representatives.
  • Page 44 9-2 LOW-PASS FILTER CHARACTERISTIC Item 1) shows the characteristic of the low-pass filter incorporated in the DPM-900A series. In item 1), the frequency characteristic is normalized against a cutoff frequency. About the relation between the amplitude and the phase, first obtain the ration of F/Fc, and then read it from the diagram below.
  • Page 45 9-3 HOW TO CALCULATE STRAINS This section describes how to measure strains and stress with the DPM-900A series. 9-3-1 Method of Calculation Applicable to Strain Gage Suppose that a strain waveform as shown at right was Calibration Wavaform Waveform of Measuring Variable (CAL) obtained.
  • Page 46 4) Frequency of the strain waveform If vibrations are periodically generated, a frequency can be calculated. Measure the length of 10 or so cycles, then obtain their average t [mm]. Compare the result with the marker interval, tc. × [sec] From T , the frequency f is obtained by using the equation below.
  • Page 47 (2) When using 4 strain gages in the arrangement shown in the right, multiply the measurement value ε by 1/4. ε ε ε σ × ε × 2) When using active gage and dummy gage (1) When using 2 strain gages in the arrangement shown in the right, multiply ε...
  • Page 48 The DPM-900A series is designed to measure strains. The amount of a measured strain has to be converted into a physical quantity by using the calibration factor or the rated output stated in the Test Data Sheet of the strain gage transducer.
  • Page 49 Smaller the setting value of After setting the internal gain (ACTL mode) than ×20000) is set. the VOLTAGE OUT switch and set the internal gain again. Contact KYOWA or our representatives even if the error indication appears after conducting the remedies.
  • Page 50 The same thing happened when the shielded cable and grounding terminal are short circuited. When measuring strain of the target having the electric potential with the shielded cable connected, the DPM-900A series may broken since it has no isolation.
  • Page 51 10. GLLOSARY TEDS TEDS is an acronym for Transducer Electronic Data Sheet. It is a table of digitized sensor’s information that is held in the transducer. Capable of conducting applicable measurement without manual setting by reading the information with the TEDS-compatible amplifier.
  • Page 52 Excitation Voltage The voltage or a power source, AC or DC, connected to a Wheatstone bridge. The higher an excitation voltage, the larger a Wheatstone bridge’s output voltage grows. An excitation voltage should, therefore, be decided according to the kind of a measuring object and that of a strain gage. Active gage A gage which is bonded to the strain generating area of a measuring object.

This manual is also suitable for:

Dpm-911aDpm-912a