Omega DLC101 Owner Manual
The Omega DLC101 is a Force Sensor which is designed to measure dynamic forces over a very broad frequency range (quasi-static to 25 kHz), available in six ranges: 10, 50, 100, 500, 1000 and 5000 LbF F.S. for 5 Volts output.
The sensor has a radially mounted electrical connector and utilizes a separate 1-28 mounting stud. It is ideal for driving point force measurements in vibration testing, drop shock testers, impact hammer devices or for instrumenting shafts and pushrods.
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O Г" © dh © == N Force Sensor Operator’s Manual M1642/0493 2 = OMEGA An OMEGA Technologies Company Servicing USA and Canada: Call OMEGA Toll Free OMEGA Engineering, Inc. One Omega Drive, Box 4047 Stamford, CT 06907-0047 U.S.A. Headquarters: (203) 359-1660 Sales: 1-800-826-6342 / 1-800-TC-OMEGA Customer Service: 1-800-622-2378 / 1-800-622-BEST Engineering: 1-800-872-9436 / 1-800-USA-WHEN FAX: (203) 359-7700 TELEX: 996404 EASYLINK: 62968934 CABLE OMEGA Servicing Europe: United Kingdom Sales and Distribution Center OMEGA Technologies Ltd. P.O. Box 1, Broughton Astley, Leicetershire LE9 6XR, England Telephone: (0455) 285520 FAX: (0455) 283912 The OMEGA Complete Measurement and Control Handbooks & Encyclopedias™ vr Temperature vr pH and Conductivity vr Pressure, Strain & Force w Data Acquisition Systems x Flow and Level w Electric Heaters ШТО ATH 1} A HAI i, VOLUME 28 | HE ne E dA К ad £4 lad FET i Call for Your FREE Handbook Set Today: (203) 359-RUSH TA er В ate DLC101 TABLE OF CONTENTS Section Page Number Introduction arre. PS 1 Unpacking the Sensor............. LL A AA 1 Description aa nrrrrrrerreririo 1 Theory of Operation... ... LL LL A 1 Polarity of Output Signal ..................... LL ria 1 Sensitivity ............ LA aa aa AL A reir 1 User Precautions ............... La LL a LL LA aan rr ri 1 Installation ....... LL LA A AAA aa AAA AA rraaarer air 2 Start-Up .........100L LL LA AL AA AAA A0 2 Loading Considerations ............................ A aaaraar ra 2 Quasi-Static Considerations............................ nar ree 2-3 Calibration ......... LL LL aa aa AAA e 3 Maintenance ............. La aa AA AAA aaarrrr reo. 3 INTRODUCTION The OMEGA Model DLC101 Series Force Sensors are designed to measure dynamic forces (from 10LbF full scale to 5000 LbF full scale) over a very broad frequency range (quasi-static to 25 kHz). These sensors are available in six ranges: 10, 50, 100, 500, 1000 and 5000 LbF F.S. for 5 Volts output. Thin X-cut quartz crystals produce a voltage analagous to dynamic force inputs, positive for compression and negative for tension. An integral IC amplifier with a MOSFET input stage converts this very high impedance signal to a low impedance output voltage. This type of amplifier is capable of driving long cables and is unaffected by cable length or type, triboelectric noise and most other sources of noise. The integral IC is powered by a simpie current source power supply. Connections from power unit to sensor can be made with coaxial cables, less expensive twisted pair or other types of twin conductor cables. The DLC101 force sensor has a radially mounted electrical connector and utilizes a separate 1-28 mounting stud. UNPACKING THE SENSOR Remove the packing list and verify that you have received all equipment. If you have questions about the shipment, please call the OMEGA Customer Service Department at (800) 622-2378 or (203) 359-1660. Upon receipt of shipment, inspect the container and equipment for any signs of damage. Note any evidence of rough handling in transit. Immediately report any damage to the shipping agent. DESCRIPTION The Model DLC101 is ideal for driving point force measurements in vibration testing, drop shock testers, impact hammer devices or for instrumenting shafts and pushrods. The upper platen distributes the input force evenly across the crystals while sealing the sensor from moisture. The very thin quartz crystals that can be seen in Figure 1, comprise a relatively small part of the overall height of the sensor. This allows for very high stiffness (rigidity), almost the same as a like part made from solid steel. Refer to the installation drawing included with the manual for a more detailed description of the DLC101. Tapped Hole Platen Preload Screw Quartz Plates Electrode se IC Amplifier \ \ Electrical Connector FIGURE 1 - Cross Section - Model DLC101 Figure 1 shows that the DLC101 features a radially- mounted amplifier housing and electrical connector. THEORY OF OPERATION SENSOR POWER UNIT Constant Current Diode Coupling Capacitor - Cable ит ттт сы C2 | i | I ! | L — — EEE A nl | ный — mal Quartz Element Bipolar DE Voltage Source Readout Load FIGURE 2 - System Schematic Figure 2 illustrates the sensor/cable/power unit/ readout system schematically in its simplest form. The input force stresses the quartz crystals producing an electrostatic charge Q, which charges total shunt capacity C instantly to voltage V. Thus: (V= ©) C The MOSFET input IC amplifier operating in unity gain, source follower mode, is supplied with constant current from the power unit via a single coaxial cable. The voltage signal from the crystal/capacitor combination is connected to the MOSFET gate and results in a like signal at the source, identical in amplitude but superimposed on a +11 Volt bias level. This source terminal is the center contact of the coaxial connector on the sensor. The +11 VDC level is “removed” or blocked by the 10uf capacitor in the power unit, thereby returning the output signal to a zero bias condition. Power can be supplied to this system by an OMEGA accelerometer power supply. POLARITY OF OUTPUT SIGNAL Compressive force on these sensors produces positive-going output signals while tensile forces produce negative-going output voltages. SENSITIVITY The voltage sensitivity of each sensor is fixed by crystal constants and dimensions and by the value of shunt capacitance C (Figure 2) at the time of manufacturing and cannot be changed. The exact sensitivity is shown on a calibration certificate supplied with each sensor. Consult the chart of sensitivities and ranges on the specification sheet for the nominal sensitivity of the various models. USER PRECAUTIONS Do not exceed maximum temperature or force ratings. Do not apply voltage from DC power supply or battery directly to electrical connector. This would immediately destroy the integral electronics. INSTALLATION For most applications, the impact cap (supplied) will be used at the load platen. 1. Thread cap into place securely, inspecting for foreign particles between mating surfaces. For this section, refer to Figure 3 below. 1/4-2& Tapped Hole, == ==——— Impact Cap (Supplied) .175 Deep, Both Ends и нм Обе . TV ; fc селей | | ma” — Electrical Connector —— | ho 10-37 Coaxial == "Mounting Stud, 1/4-28 UNT {Supp! ied) — L623 Diameter Minimum—— — Mounting Surface — - Що CSSS ill v3 (L213) Dia. +“ . - toa —— . 2.235€ Deep, Tap i/a—26 To - «WE=2E L180 Minimum Depth _— 7 Ferfect Tnread, mr a TT FIGURE 3 - Installation 2. Prepare a flat, smooth area. Drill and tap a %-28 hole in the center of this area. 3. Check for burrs and other particles and torque the DLC101 into place using the 1-28 mounting stud (supplied). It is necessary that the mating surfaces be In intimate contact for proper operation of the sensor. A small amount of epoxy may be used on the threads of the stud for a more permanent installation. 4. Connect sensor to power unit as shown in Figure 4, using an ACC-CB2 coaxial cable. Tighten cable locking rings by hand. Neta! UE Tio FIGURE 4 - Electrical Interconnections START-UP 1. Connect the power supply to the readout instrument using an ACC-CB2. 2. Switch power unit on and wait several minutes for coupling capacitors to fully charge and for the system to thermaliy stabilize. During this warm-up period, the system output voltage may appear to be unstable, that is, slowly changing in value. This is normal and the system should stabilize within two to three minutes. LOADING CONSIDERATIONS When applying loads to the DLC101, it is important to remember that the load must be distributed evenly across the force sensitive surface. Avoid “Point” loading. The impact cap should be used in all impact and other compressive measurement situations where the load is not fastened directly to the tapped hole in the force sensitive surface. - F Г TT | Te Hydraulic | | Cylinders Steel Bali Adaptor i > WRONG RIGHT FIGURE 5 - Proper Loading Method Figure 5 shows the proper way to measure the dynamic force produced by a hydraulic ram. The right Way uses a steel ball and adaptor to transmit the force to the load cell, distributing the force evenly across the cell surface. The wrong way shows the ram contacting the cell at the highest point, off center, with no provision for the proper mating of the two surfaces. An erroneous force reading would most probably result from this set-up. lireadea Eye Hooks = | \ hydraul ic Cvlinder | | FIGURE 6 - Tension Measurement Figure 6 shows an acceptable loading method for measuring the tensile force of a ram. The two hook eyes provide the degrees of freedom necessary to ensure that the cell is loaded in pure tension without bending moments being applied to the DLC101. You can also use rod-end bearings. QUASI-STATIC CONSIDERATIONS The discharge time constant of some DLC101 models is long enough so that near static force measurements can be made. However, it is important to consider other coupling time constants in the measurement system to obtain the desired results from the sensor. The integral IC is powered by a single coaxial cable with 2 to 20 mA of constant current (See Figure 7). The voltage produced by force acting upon the sensor is superimposed on a +11 V bias voltage at the sensor connector. —— To Sensor 10uF | SR DC Voltage R Source in Power $ lv “ppl Readout FIGURE 7 - Decoupling Considerations Most power supplies are AC coupled, which means that they utilize a 10uf tanalytic capacitor to decouple the sensor signal from the sensor. This effectively returns the signal level to zero base and “removes” the +11 VDC bias. It must be remembered that in most cases, this 10uf capacitor loaded by the input resistance of the readout instrument will limit the quasi-static ability of the sensor system. For Example: If the input resistance of the readout instrument is 1 megaohm, the discharge time constant for the coupling circuit is: 10uf x 1 meg ohm = 10 seconds This result says that within .1 second (10 x .01) after application of a static force, disregarding the discharge time constant of the load cell itself, 1% of the signal information will be lost. ~ A 10 meg ohm readout impedance yields a discharge TC of 100 seconds. Now after one second, 1% of the information is lost — a little better, but still not good enough for a quasi-static reading. If the +11 Volt offset can be handled by the readout instrument, a simple “T” connection at the readout may be used to direct couple the sensor to the readout. кН В "1" NC Force Sensor ' Power Supply FIGURE 8 - Direct Coupling Figure 8 shows that using this type of connection allows a standard AC coupled power supply to be utilized. An adjustable “floating” DC power supply can also be used with the set-up shown in Figure 8 to “buck out” the DC bias and return the output level to zero Volts. CALIBRATION Since these sensors are dynamic transducers that are designed to measure impacts or rapidly changing forces, it is best to calibrate them dynamically. The sensors are calibrated at the factory by impacting them with a known, calibrated force hammer. Another method is to drop a carefully weighed mass/ accelerometer assembly onto the force sensor. in view of the fact that force (F) is equal to mass (m) times acceleration (a), the force cell can be calibrated if the exact weight of the accelerometer/mass system and the precise calibration of the accelerometer are known. This is an implementation of Newton's 2nd law: F = mA. A third method is to apply and remove calibrated weights. This must be done very carefully for repeatable results and cushioning must be used between sensor and weight. Use some form of storage oscilloscope (preferably a digital model) or a peak meter as a readout instrument for all of these calibration methods. MAINTENANCE The sealed construction of these sensors precludes field repair. Wipe the electrical connector with Freon TF solvent, methylene chioride or alcohol to remove oil, dirt and other contaminants. Since the output impedance is very low, it is not necessary to maintain super-high impedances at the electrical connector as with high impedance sensors without built-in electronics. DLC101 SPECIFICATIONS Excitation: Rated Output: Resonant Frequency (O no load): High Frequency Range: Low Frequency Range: (-3 dB) Discharge Time Constant: Maximum Compression: Maximum Tension: Stiffness: Overload Recovery: Maximum Shock/ Vibration: (no load, g) Amplitude Linearity: Temperature Range: Temperature Sensitivity Effect: Output impedence: Bias Voltage: Noise Floor (wideband, RMS): Weight: Material: Diameter of Top Force Sensitive Surface: Mounting Holes: Connector: 2 mA nominal @ 18-30 Vdc, constant current 5 Vdc nominal FS 75 kHz 25 kHz (approx. 1/3 of resonant frequency) 0.08 Hz 50 sec (DLC101-10) 100 sec (DLC101-50) 500 sec (DLC 101-100) 2,000 sec (DLC101-500, -1K, -5K) 200 Ib (DLC101-10) 1,000 Ib (DLC101-50) 2,000 Ib (DLC101-100) 10,000 Ib (DL C101-500) 15,000 Ib (DLC101-1K) 15,000 ib (DLC101-5K) 200 Ib (DLC101-10) 500 Ib (all ranges except for 10 Ib) 11.4 167 nin. 10 us for 2X range 10,000/+5,000 g's +1% FS (BSFL/0) -100 to 250 deg F (-75 to 120 deg C) .03% F.S./deg F 100 Ohms 10V nominal 0.00014 Ib (DLC101-10) 0.0007 Ib (DLC101-50) 0.0014 Ib (DLC101-100) 0.007 Ib (DLC101-500) 0.014 Ib (DLC101-1K) 0.07 Ib (DLC101-5K) 1.5 02 nominal 17-4 ph stainless steel housing (Rc 44) 0.50” 7-28 x .175 deep tapped hole integral side coaxial, 10-32 male termination (cable not included - order P/N ACC-CB2-10) *Use ONLY constant current type power supplies. DO NOT supply power from non-current limited power supplies. OS Ре [USA E WARRANTY cuan т OMEGA warrants this unit to be free of defects in materials and workmans service for a period of 13 months from date of purchase. OMEGA Warranty adds an additional one (1) month grace period to the normal one (1) year product warranty to cover handling and shipping time. This ensures that our customers receive maximum coverage on each product. If the unit should malfunction, it must be returned to the factory for evaluation. Our Customer Service Department will issue an Authorized Return (AR) number immediately upon phone or written request. Upon examination by OMEGA, if the unit is found to be defective it will be repaired or replaced at no charge. However, this WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence of being damaged as a result of excessive corrosion; or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating conditions outside of OMEGA's control. Components which wear or which are damaged by misuse are not warranted. These include contact points, fuses, and triacs. We are glad to offer suggestions on the use of our various products. Nevertheless OMEGA only warrants that the parts manufactured by it will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF TITLE AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF LIABILITY: The remedies of buyer set forth herein are exclusive and the total liability of OMEGA with respect to this order, whether based on contract, warranty, negligence, indemnification, strict liability or otherwise, shall not exceed the purchase price of the component upon which liability is based. In no event shall OMEGA be liable for consequential, incidental or special damages. Every precaution for accuracy has been taken in the preparation of this manual; however, OMEGA ENGINEERING, INC. neither assumes responsibility for any omissions or errors that may appear nor assumes liability for any damages that result from the use of the products in accordance with the information contained in the manual. HE RHEE: TRE HE ET pt en a a pe, НН tr tnt i SEE ra FH sp Ginn HH | mr RETURN REQUESTS / INQUIRIES mma Direct all warranty and repair requests/inquiries to the OMEGA ENGINEERING Customer Service Department. Call toll free in the USA and Canada: 1-800-622-2378, FAX: 203-359-7811: International: 203-359-1660, FAX: 203-359-7807. BEFORE RETURNING ANY PRODUCT(S) TO OMEGA, YOU MUST OBTAIN AN AUTHORIZED RETURN (AR) NUMBER FROM OUR CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the return package and on any correspondence. FOR WARRANTY RETURNS, please have the FOR NON-WARRANTY REPAIRS OR CALIBRATION following information available BEFORE consult OMEGA for current repair/calibration contacting OMEGA: charges. Have the following information available 1. PO. number under which the product was BEFORE contacting OMEGA: PURCHASED, 1. Your PO. number to cover the COST of the of the 2. Model and serial number of the product repair/calibration, under warranty, and 2. Model and serial number of product, and 3. Repair instructions and/or specific problems | 3. Repair instructions and/or specific problems you you are having with the product. are having with the product. OMEGA's policy is to make running changes, not model changes, whenever an improvement is possible. That way our customers get the latest in technology and engineering. OMEGA is a registered trademark of OMEGA ENGINEERING, INC. © Copyright 1993 OMEGA ENGINEERING, INC. All rights reserved including illustrations. Nothing in this manual may be reproduced in any manner, either wholly or in part for any purpose whatsoever without written permission from OMEGA ENGINEERING, INC. Printed in U.S.A. OMEGA”... 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Key features
- Measures dynamic forces from 10LbF to 5000 LbF
- Broad frequency range from quasi-static to 25 kHz
- Voltage output proportional to force
- Integral IC amplifier with MOSFET input stage
- Unaffected by cable length or type, triboelectric noise
- Radially mounted electrical connector and separate mounting stud
Frequently asked questions
5000 LbF
Quasi-static to 25 kHz
Voltage output proportional to force
No, the DLC101 is unaffected by cable length or type
Yes, the DLC101 can measure forces in both compression and tension