Manual de funcionament i servei
Tension And Compression
Load Cell • Model 3397

ADVERTIMENT – SEE SAFETY NOTE INSIDE TO AVOID THE POTENTIAL FOR PERSONAL INJURY.

Ús previst

This load cell may be used in either tension or compression. It is a general-purpose unit for application in dynamometers, weighing, test stands, and similar devices.

Nota de seguretat

Personal injury to the operator, as well as damage to equipment, can result if the load cell is operated with an improper combination of main axis load and extraneous load. To avoid catastrophic failure (separation of load cell structure), the load must be limited to 100% of the main axis nominal load limit combined with 200% of any one of the extraneous load limits from the chart on page 4. If 200% of a main axis load limit is applied, no other extraneous loads can be combined with it.
To avoid non-catastrophic failure (degradation of specifications) of the load cell, the load restrictions given in the chart on page 4 must be observed.

Certificate of Conformance and Calibration Traceability

This is to certify that the products described herein meet the specifications and performance requirements described in this manual. Test reports and other pertinent information are on file and available for inspection by your representative and/or the U.S. Government representative upon request.

Calibration was performed with a test system utilizing a reference load cell or deadweights and an electronic indicator. The test system was within current calibration requirements at the time of the test and is traceable to the NIST.
LeBow Products, Troy, Michigan

Limited Warranty-Product Liability
The Company’s products are warranted to be free from defects in material and workmanship for one year from the date of shipment from the factory. The Company’s obligation is limited to repairing, or, at its option, replacing products and components which, on verification, prove to be defective, at the factory in Troy, Michigan. The Company shall not be liable for installation charges, for expenses of Buyer for repairs or replacements, for damages from delay or loss of use, or other indirect or consequential damages of any kind. The Company extends this warranty only upon proper use of the product in the application for which intended and does not cover products that have been modified without the Company’s approval, or that have been subjected
to unusual physical or electrical stress, or upon which the original identification marks have been removed or altered. Transportation charges for material shipped to the factory for warranty repair are to be paid by the shipper.
The Company will return items repaired or replaced under warranty prepaid. No item shall be returned for repair without prior authorization from the Company.
Whenever the design of the equipment to be furnished or the system in which it is to be incorporated originates with the buyer, the manufacturer’s warranty is limited specifically to matters relating to the furnishing of equipment free of defects in material and workmanship, and assumes no responsibility for implied warranties of fitness for purpose or use.

Principis de funcionament

The Model 3397 load cell is a precision designed struc-ture which has exceptional capability to withstand extraneous loads such as torque, side loads, and bending moments (see table on page 4).
Force applied to the cell is translated into an electrical signal by means of changes in the electrical resistance of strain gages bonded to the interior structure of the unit. The strain gages are connected in a 4-arm (Wheatstone bridge) configuration network. This arrangement allows temperature compensation as well as largely cancelling signals caused by extraneous loading.

A fixed excitation voltage is applied between A and D of the bridge. Load applied to the structure unbalances the bridge, causing an output voltage to appear between B and C. This voltage is proportional to the applied load.

Instal·lació

The Model 3397 load cell may be operated either horizontally or vertically, or at any angle in between, provided the load is applied straight through the loading axis, i.e., on the center line of the threaded holes. The cell is sealed and compensated for normal barometric changes. It will withstand operation in areas of high humidity, but is not intended to be immersed.
For use in which both tension and compression forces may be applied (such as in a trunion-mounted dynamo-meter), use of spherical rod end bearings is recommended. For compression only, a load button should be mounted at the top of the cell.
NOTA: Load button thread length must be 5/16″ ± 1/16″. Torque the load button to 30 in. Ibs. Rod ends should be threaded into the center holes until they bottom out, then backed out one turn. Torque the rod end jam nuts to 30 in. lbs.

Wiring (Each bridge)

When connected as shown, output goes up-scale (positive) for tension loads. WESTERN Regional Code.

Use only shielded cable to connect the cell to the indicator. The use of Belden Cable (or equivalent quality) is recommended. Use Belden 8723 for cable 20 feet or less. Use Belden 8725 for cables over 20 feet.
Use 60/40 rosin core solder for connections and clean with rosin solvent after soldering. Check all connections for continuity. There should be at least 5000 megohms of resistance between adjacent pins of the cable when it is disconnected at both ends. Connections at the read-out instrument are to be made according to the instrument manufacturer’s instructions.

NOTA: A connector mating with the cell (Bendix PTO-6-W10-6S) is supplied with the cell.

NOTA: The values shown are valid only if the shunt is connected at or near the load cell and the indicator used has an input impedance of at least 50k ohms.

Especificacions

SENSOR: 4-arm strain gage bridge
EXCITATION VOLTAGE: 20 VDC or VAC RMS Max.
ZERO BALANCE: Within 1% of rated output
REPETIBILITAT: 0.02% de l'escala completa
SOBRECÀRREGA: 150% of rated capacity
EFFECT OF TEMP. ON ZERO: 0.002% of F.S./°F
EFFECT OF TEMP. ON OUTPUT: 0.002% of F.S./°F
COMPENSATED TEMP. RANGE: De 70 °F a 170 °F
USEABLE TEMP. RANGE: -65 °F a 200 °F
SHUNT CALIBRATION: An electrical signal equivalent to that produced by a known load can be obtained by shunting one arm of the load cell’s strain gage bridge with a precision wire-wound resistor. Shunt resistor and equivalent load values for this load cell are shown above. They are determined during factory calibration of the load cell.

Solució de problemes

1. Check power and load cell connections to the indicator.
2. Check the load cell cable for correct interconnection with the indicator in use.
3. Verify the cell’s excitation and signal resistance as shown on page 3.
   Precaució: The ohmmeter should not apply more than 10 volts to the load cell bridge.
4. Check bridge resistance to ground (case of cell) with a 50 volt megohmmeter. Should be greater than 5K megohms.

Model 3397

Extraneous Load Considerations

Excessive side loads and bending moments applied to a load cell will degrade its accuracy and may damage it. Care should be exercised to ensure that forces are applied to parallel to, and in line with, the cell’s measurement axis.

			LIMIT LOADS
Capacity (P) lbs.	Static Overload Capacity % of Nom. Capacity	Desviació en.	Bending Moment  Mx or My polzades-lbs.	Cisalla Fx or Fy lliures.	Torque Mz lb.-in.
25	150	0.003	150	150	40
50	150	0.003	150	150	40
100	150	0.003	180	250	40
200	150	0.003	180	250	40
300	150	0.003	180	250	40

Static extraneous limits are calculated such that only one extraneous load (Fx, Fy, or Mx or My, or Mz) can be applied simultaneously, with half the nominal load limit capacity.

Maintenance and Recalibration
This load cell may be stored for an indefinite period at room temperature in a dry place.
Recalibration should follow your normal instrument certification schedule.

Accessoris disponibles

1. Overload Protectors (consult factory).
2. Load Buttons for the compression application. Part No. A11277.
3. Rod Ends (spherical) for tension/compression application. Part No. A26096.
4. Dust Cap and Chain to protect the load cell receptacle when the cell is not in use. Part No. 219-003.
5. Cable assemblies (consult factory).

Form IM 110/0/04
Imprès als EUA

Documents/Recursos

Lebow 3397 Load Cell [pdfManual d'instruccions 3397, 3397 Load Cell, Load Cell

Referències

• Manual d'usuari