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26 

Defender

™ Series Bases Service Manual 

APPENDIX A.

  

GLOSSARY 

Ohaus Load Cells contain a specification label on the Load Cell itself. 

Compensated Temperature Range 

The range of temperatures over which the output from the cell is compensated.  If used outside this 
range the output cannot be guaranteed to follow the specifications. 

Environmental Protection

 

IP rating against moisture and dust, for example, IP 65. 

Excitation

 

Voltage applied to the Exe+ and Exe

– leads of the load cell. 

Input Resistance 

The resistance measured across Exe+ and Exe

– with load cell disconnected and 

no load. 

Insulation Resistance

 

Normally measured at 50 V dc, this is the minimal resistance between the metal body of the load cell 
and any of its electrical connections. 

Mechanical Failure

 

The load at which the cell is likely to fail mechanically, that is, break or deform. 

mV/V 

Usually the output from a load cell will be approximately 0m V at zero load, though typically there may 
be a small offset voltage at zero load.  Over the full rated capacity of the load cell, the mV output will 
change.  The amount by which it changes depends upon the resistance change in the cell and on the 
excitation voltage applied.  Since the load cell manufacturer does not know what excitation voltage will 
be applied to the cell, rather than quote the V output over full range, they will quote the milli-Volt output 
per volt of excitation, or in its short form, mv/V. Most Ohaus Indicators provide an excitation voltage of 
5 Volts dc. 

Output Resistance

 

The resistance measured across S+ plus and S

– with load cell disconnected and 

no load. 

Overload Capacity

 

The maximum load that can be applied without permanent damage.  Loads in excess of maximum 
capacity will cause damage to the load cell. 

Rated Capacity

 

The maximum load over which the load cell will operate within its specifications. 

Rated Output

 

The nominal mV/V output of the load cell. 

Ultimate Capacity 

This is a percentage setting, usually 300% of full capacity. 

Zero Balance

 

The output of the load cell at no load, normally quoted as a percentage of full load.  Also known as 
zero offset. 

Summary of Contents for DEFENDER SERIES

Page 1: ...Defender Series Base Service Manual 99 Washington Street Melrose MA 02176 Phone 781 665 1400 Toll Free 1 800 517 8431 Visit us at www TestEquipmentDepot com...

Page 2: ...oubleshooting 12 2 1 1 Checking Load Cells for Trouble 12 CHAPTER 3 MAINTENANCE AND REPAIR PROCEDURES 13 3 1 Preventive Maintenance 13 3 1 1 Preventive Maintenance Checklist 13 3 2 Replacing the Load...

Page 3: ...ional and performance tests and adjustments Chapter 5 Parts Identification Contains exploded views of Defender series Bases and parts identifying all serviceable components with parts lists Before ser...

Page 4: ...door use and should only be operated in dry locations Operate the equipment only under ambient conditions specified in the user instructions Do not operate the equipment in hazardous or unstable envir...

Page 5: ...is direct replacement of Load Cells with connecting cable and hardware The Defender series Base contains the following basic replaceable assemblies Platform Load Cell with Connecting Cable and Down S...

Page 6: ...0 lb 25 kg 100 lb 50 kg 100 lb 50 kg 250 lb 125 kg Approved Resolution NTEP and Measurement Canada 5000e Safe Overload Capacity 150 of capacity Pan Dimensions 305 x 305 mm 12 x 12 in 305 x 355 mm 12 x...

Page 7: ...city Pan Dimension s 457 x 610 mm 18 x 24 in 610 x 610 mm 24 x 24 in 600 x 800 mm 24 x 31 5 in Base Constructi on Stainless Steel platform with painted steel frame and rubber leveling feet Load Cell C...

Page 8: ...4 mm 10 x 10 mm 305 x 305 mm 12 x 12 in 457 x 457 mm 18 x 18 in Base Construction Stainless Steel platform with stainless steel frame and rubber leveling feet Load Cell Capacity 6 kg 10 kg 30 kg 30 kg...

Page 9: ...7 x 610 mm 18 x 24 in 610 x 610 mm 24 x 24 in Base Construction Stainless Steel platform with stainless steel frame and rubber leveling feet Load Cell Capacity 150 kg 300 kg 500 kg 150 kg 300 kg 500 k...

Page 10: ...Figure 1 1 Typical Strain Gauge Load Cell The strain gauges are wired into a Wheatstone Bridge Circuit See Figure 1 2 Figure 1 2 Downward force on the Platform bends the beam causing two gauges to str...

Page 11: ...es as weight is loaded to the Load Cell For example a 500kg Load Cell with 2mV V output and 5V excitation would have a change of 0 02mV per kg change in the load that is 10mV 500 0 02mV per kg At a lo...

Page 12: ...11 Defender Series Bases Service Manual Type2 DxxxRxx Bases FUNCTION WIRE COLOR Excitation Green Excitation Black Signal White Signal Red Sense Blue Sense Brown Shield Yellow...

Page 13: ...ld restrict movement causing improper operation of the Base If the Overload Stops are improperly set adjust them See Section 3 3 Check the metal surfaces of the Platform All surfaces should be paralle...

Page 14: ...e 2 Remove the Platform to inspect and clean the area beneath the Platform CAUTION DO NOT USE CHEMICAL CLEANERS OR SOLVENTS OF ANY TYPE SOME CLEANERS ARE ABRASIVE AND MAY AFFECT THE BASE S FINISH 3 Ch...

Page 15: ...Gap 4 Re adjust if necessary 5 Cover the Platform and check for full capacity See Table 3 1 for Gap settings TABLE 3 1 OVERLOAD GAP SETTINGS FOR DEFENDER SERIES BASES Base Model Pan size Overload Stop...

Page 16: ...1 3 5 Y D150WTDL 1 5 6 Y D60RTL 1 1 5 N D150RTL 1 5 2 5 Y D60WTL 1 3 5 Y D150WTL 1 5 6 Y D50RTX 457 x 610 18 x 24 0 8 1 5 N D125RTX 1 2 2 5 Y D250RTX 1 5 3 5 Y D50WTX 0 8 3 5 Y D125WTX 1 6 Y D250WTX 1...

Page 17: ...nder Series Bases Service Manual D125RTV 600 x 800 23 6 x 31 5 1 2 3 5 N D150RTDV 0 9 3 5 N D250RTV 1 8 5 N D300RTDV 1 2 6 N D500RTV 2 2 9 N D600RTDV 2 2 8 N D150WTDV 1 6 Y D300WTDV 1 2 9 N D600WTDV 1...

Page 18: ...isconnected from the Indicator and at no load when these tests are made In addition to the four resistance elements which make up the Wheatstone Bridge there are commonly one or two resistors in the e...

Page 19: ...the signal voltage 4 Obtain the mV V output figure from the Load Cell data supplied with the Load Cell and compare the signal changes seen with the theoretical values from the Load Cell data See Tabl...

Page 20: ...t cannot be passed the Load Cell must be adjusted or replaced Prior to starting this test the Base must be connected to a properly functioning Indicator with capacity and readability values set accord...

Page 21: ...to point D and record the reading 7 If the reading at point A is negative file at points 1 and 4 AT AN ANGLE 8 If the reading at point B is negative file at points 1 and 2 STRAIGHT ACROSS 9 If the rea...

Page 22: ...Bases The exploded view drawings are designed to identify the parts which can be serviced in the field ATTENTION In all cases where a part is replaced the base must be thoroughly checked after the re...

Page 23: ...22 Defender Series Bases Service Manual CHAPTER 5 PARTS IDENTOFICATION 5 1 Defender series Base Carbon Steel model Figure 5 1 Defender series Base D52 RQR...

Page 24: ...806 Hardware Kit R Base D52 5 30427876 Load Cell 0785 22kg 2m For D12RQR 30427877 Load Cell 0785 50kg 2m C3 5 For D25RQR 30448396 Load Cell 0785 50kg 2m C3MI For D30RQR 30427878 Load Cell 0785 100kg 2...

Page 25: ...24 Defender Series Bases Service Manual 5 2 Defender series Base Stainless Steel model Figure 5 2 Defender series Base D52 WQR...

Page 26: ...0785 22kg 2m C3MI For D15WQDR 30448396 Load Cell 0785 50kg 2m C3MI For D30WQDR D30WQR 30448267 Load Cell SLP532 30kg C3 2m For D15WQR D12WQR 30448388 Load Cell SLP532 50kg C3 2m For D25WQR 30448389 Lo...

Page 27: ...ere may be a small offset voltage at zero load Over the full rated capacity of the load cell the mV output will change The amount by which it changes depends upon the resistance change in the cell and...

Page 28: ...30479276A P N 30479276A 2018 OHAUS Corporation all rights reserved 99 Washington Street Melrose MA 02176 Phone 781 665 1400 Toll Free 1 800 517 8431 Visit us at www TestEquipmentDepot com...

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