Measurements Group Strain Gauge Instrumentation

Model 1300 Gauge Installation Tester 

Deterioration of the insulation resistance with time may be an indication of an improperly coated installation.

At higher test temperatures, particularly above +300 deg F (+150 deg C), it is normal to expect lesser values. Ten mega ohms is considered to be the lower allowable value.

A voltage difference between the specimen and strain gauge frequently exists. A very high insulation resistance will help keep this voltage differential from introducing extraneous signals during strain measurement.

Shifts in gauge resistance during installation should not normally exceed 0.5% when using room-temperature-curing adhesives. Resistance shifts greater than 0.5% generally indicate damage to the gauge due to improper handling or clamping. However, strain gauges installed using elevated temperature-curing adhesives may exhibit greater shifts in resistance due to adhesive lock-up at elevated temperatures (difference in linear coefficient of thermal expansion between the strain gauge and specimen). These shifts will vary depending upon the specific cure temperature and materials used. The shifts should never exceed 2% and should be uniform within 0.5%.

The Model 1300 was jointly designed by the Micro-Measurements and instruments Divisions of Vishay Measurements Group for maximum usability. The unit's payback is very short as it will identify faulty gauge installations that could ruin a costly test program. 

Features

• Reads with the Push of a Button: No Warm-Up. 

• Reads Insulation Resistance (Leakage) to 20 000 Mega ohms with 15 Vdc. 

• Measures Deviation of Installed Gauge Resistance from Precise Standards to a Resolution of 0.02 Percent. 

• Ohmmeter Scale for Troubleshooting Questionable Installations. 

• Verifies the Complete Gauge Circuit Including Leadwires. 

Specifications
All specifications nominal or typical at +23 deg C unless noted.

Input Circuits
Gauges: 3-wire quarter bridge (120 and 350 ohms) and half bridge. Other value quarter bridges using customer's reference, at readily accessible panel terminals.
As ohmmeter: 2 leads (500 ohms and 500 mega ohms midscale).

Input Leads
4-ft (l.2-m) 4-conductor AWG#26 (0.4-mm dia.) twisted Teflon-insulated cable supplied (with ground clip and 3 tinned leads).

Meter
3.5-in size [3.00-in (76-mm) scale length] with mirror. Tracking accuracy +1% full range.

Mode Switch
5 momentary push buttons: battery check, +5% deviation, +l % deviation, gauge resistance (ohms), and insulation resistance (megohms).

Deviation Mode
Two ranges, +1% and +5% F.S. (50 graduations either side of zero).

Accuracy: 
1% range: 0.04% (2 meter graduations)
5% range: 0.2% (2 meter graduations)
Excitation: 1.0 Vdc per gauge.

Insulation Resistance Mode 
Graduated 5 megohms to 20 000 megohms (500 megohms mid-scale).
Accuracy: 1 scale div.
Test Voltage: 15 Vdc open circuit.

Ohm Mode 
Graduated 5 ohms to 20 000 ohms (500 ohms mid-scale).
Accuracy: 1 scale div.
Test Voltage: 2 Vdc open circuit (0.4 Vdc at 120 ohms).

Enviromental
+15 deg to +125 deg F (-10 deg to +50 deg C); up to 90% relative humidity, non-condensing.

Size
Aluminium case (separable lid)
5 H x 7 W x 5 D in with lid
(125 x 180 x 125 mm).

Weight
3.6 pounds (1.6 kg) with batteries

Power Supply
Four 9V NEDA 1604 batteries (Eveready 216 or equiv.)
Life: Will fully test 1000-5000 installations.