New system that does not generate measurement error
For strain gauge measurement, various bridge configurations are employed according to the number of strain gauges to be used and measuring purpose. In quarter bridge configuration, three wire method is widely used to remove the effect of temperature to gauge leadwire resistance. However, some measuring error occurs owing to gauge factor correction due to leadwire resistance and variation in the contact resistance of connection part. Our developed 1-gauge 4-wire strain measurement method serves not to induce any measurement error ascribable to the gauge factor correction and contact resistance.
(Japanese Patent No.3546203)
FEATURES (Superiority to 3-wire quarter bridge method)
Our originally developed 1-gauge 4-wire strain measurement method has the following advantages over the conventional quarter bridge 3-wire method.
- Leadwire Resistance
- In conventional method, as thick and short leadwires as possible are recommended to keep the resistance of leadwires lower. On the contrary, as the 1-gauge 4-wire method is not influenced at all by the leadwire resistance, it is possible to connect a thin and long leadwires to strain gauges.
- Contact resistance
- In conventional method, leadwire extension and connection to a measuring instrument are done by soldering or the use of exclusive connector. As the 1-gauge 4-wire method is not affected at all by contact resistance, a modular plug can be used. Because the modular plug makes leadwire extension and connection to the instrument possible by merely plugging in, the efficiency of wiring work and prevention of wiring mistake are achieved and also lead free connection is possible.
Comparison: quarter bridge 3-wire method and 1-gauge 4-wire strain measurement method
A comparison of the conventional quarter bridge 3-wire method and 1-gauge 4-wire strain measurement method highlights these features.
| Quarter bridge 3-wire method | 1-gauge 4-wire strain measurement method | |
|---|---|---|
| Lead wire thickness | Thick | Thin |
| Lead wire weight | Heavy | Light |
| Lead wire material | Use of same item required | Use of same item not required |
| Lead wire sheath color | Same color depending on measurement | Use of same item not required |
| Load on specimen | Heavy | Light |
| Transport cost | Large | Small |
| Quarter bridge 3-wire method | 1-gauge 4-wire strain measurement method | |
|---|---|---|
| Quick-connector connection | Not possible | Possible |
| Soldering | Required | Not required |
| Wiring workhours | Long | Short |
| Miswiring | Yes | No |
| Environmental friendliness | Soldering contains lead | Lead-free |
More Information
Measurement systems
With our data loggers TDS-630/-530/-150, using a TDS-602/-303 connected directly to the modular jack of the built-in switching box allows 1-gauge 4-wire strain measurement simply by using a compatible switching box.
TDS-150 100 ch (built-in max. 50 ch), battery operation
TC-32K Handheld, 5 ch (external switching box), strain, temperature, voltage, 4 “AA”
ISW-50G 1-gauge 4-wire compatible, switching box with built-in ADC
IHW-50G 1-gauge 4-wire compatible, built-in ADC, high-speed switching box
SSW-50D Compatible with 1-gauge 4-wire strain measurement, semiconductor relay type (50 ch)
FSW-10 1-gauge 4-wire compatible, channel unit for TDS-150
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