Index

The Power Interface (PI) is the central element of the GaugeLink™ system which includes the gauge and gauge calibrators.

The Power Interface is a much simpler conditioner than prior units, having only gauge excitation current and selectable gain range for each of four channels.

The GaugeLink™ system replaces internal presets for gauge parameters with preselected zero amplification settings. There is no initial gauge zero offset, that function being shifted to the Test system's data acquisition system where zero offset and voltage to metric measure are handled without electronic drift or noise.

Before a test starts, the test gauge is connected to the channel input and the 'Zero Set' voltage set on the display by adjusting the amplifier's range and span controls. Each gauge size has a specific 'Zero Set ' voltage which is factory preset. The 'Zero Set' number then becomes the equivalent voltage to the starting crack length (0 mm) of the test gauge. In setting the range and span controls, the user has set the amplifier gain so that when the crack length equals 10,0 volts, the crack will be 100% of the crack length in mm. (Example for a 40 mm gauge, the 10.0 volts will represent a 40 mm crack.)

The unconditioned differential 0- 10 volt crack length signal is called the fast signal because it will respond within milliseconds to changes in resistance. This is avaialble in both the PI 4 and PI 5 configurations.

When using the PI 5 version with peak sensing, a second differential signal for each channel is outputted providing limited holding of the maximum value of a signal within a peak cycle.

If the customer DAQ conveniently provides peak sensing within fatigue cycles so that only the fast version of the signal is needed form the PI, the user can select the Power Interface 4 which does not have peak sensing and costs less.

The Power Interface conditions four crack gauge signals simultaneously.

The GaugeLink system™ simplifies setup for any gauge size. When the test gauge is connected to the input, the Display shows an initial voltage. Using the Range and Span dials of the channel, the display is brought to the 'Zero Set' value of that gauge size. Assume that when a 30 mm gauge was first connected, the Display read 4.835 V. The "Zero Set' for the 30 mm gauge is 4.720 V, so the span is adjusted until the display reads 4.720 V. The PI amplifier is now set so that when the crack reaches 30 mm the Display voltage will be 10.000 volts. The DAQ is set so that the 0 mm units will be equal to 4.720 V and the 100 mm units will be equal to 10.000 volts. Each gauge size has its predetermined 'Zero Set' value.

Calibration of each of the four channels is conveniently set up and verified with a GagueLink™ Calibrator. This is a box having a 30 mm gauge with a 30 mm crack, trimmed so that the 'Zero Set' value of 4.720 V will be displayed when the range = 6 and the Span =678. If this value differs, the Display setting can be returned by adjusting the internal channel current adjust trimpot so that the display reads 4.720 V when the Range =6 and the Span= 678.
With the 'Zero Set' complete, the system is ready to begin collecting the data of crack length in engineering units as it relates to fatigue cycles.

The amplifier scaling of the Power Interface allows the 'Zero Sets' for all gauge sizes to provides a simple method of calibrating all gauge ranges and all zero offsets to the particular gauge connected.

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Peak Sensing

The Vf signal is also sent to the conditioners peak sense circuit so that the peak signal circuit produces Vp (Vpeak) which holds the peak signal for the duration of an individual fatigue cycle.

The Vp output is smooth, unlike the Vf signal which bounces when the gauge crack shorts within a fatigue cycle.

The gauge terminator is a passive resistance plug which is equivalent to the load of a gauge. The terminator provides the proper electrical interface for both the PI conditioner current source and the inputs of the amplifier. While the PI circuitry might function without the terminator, all good practice with electronics used in the PI requires a proper interface. The resistance of the terminator also provides a nominal gauge load which allows display voltage verification of the current supply and range functions of the amplifier. The terminator comes in one size, has no controls or adjustments and is compatible with all PI 4 and PI5 inputs.

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Cables

Cables The GaugeLink™ system includes the cables to easily connect specimens and Test Machine instrumentation. All connectors are compatible with the mating connectors to which they interface.

The Gauge Terminator and Calibrator have integral connectors which plug directly into the input connectors of the Power Interface. They can be remotely located by adding the cable input extender (CIE.)

The Test Gauge can be connected to the CIT cable for connection to the PI or extended with a CIE cable.

Similarly, the output signals may be transported through a single COT cable or extended with a combination of the COT and COE cables. COT and CIT have different connectors and cannot be interchanged.

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Power Interface Ordering Information

Identification Description
Model Number
Part Number
Price

Power Interface Basic Four channel conditioner for all crack gauges sold by Teksym Corporation,
Fast output ( not integrated) only, no peak sensing. PI 4 PI 4 $5995.00

Power interface

with Peak
Four channel conditioner for all crack gauges sold by Teksym Corporation,
Four Fast outputs (not integrated) and four simultaneous Peak outputs PI 5 PI 5 $ 7995.00

Terminator Resistive load to properly terminate Power Interface
(PI 4 or PI 5) inputs
PIT
PIT
$205

Gauge Calibrator An enclosed 30 mm gauge, resistor trimmed to the median resistance of 30 mm gauges. This calibrator is used to set the excitation current and to verify operation when troubleshooting.
GC
GC 30
$ 299.00

CIT Cable, Input - Test
Connects the Test Specimen gauge to any input channel of the Power Interface. Compatible with all Teksym crack gauges. Also compatible with CIE to extend the distance between the test gauge and Power Interface. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $20.00 plus $1.00 for every foot in length. * Example, a CIT-30 would be $ 20.00 + $ 30.00= $50.00 total.
CIT CIT-(L*) $ 20.00+$1 foot*

CIE Cable, Input - Extender
Extends the connection between the CIT and Power Interface. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $30.00 plus $1.00 for every foot in length. *Example, an ICE-40 would be
$ 30.00 + $ 40.00= $ 70.00 total. CIE CIE-(L*) $30.00+ $ 1.00/foot*

COT Cable, Output Cable - Test
Connects User's Data acquisition (DAQ) inputs to any channel Fast and peak outputs from the Power Interface. Uses 8723 cable. Also compatible with COE which extends the distance between the DAQ and Power Interface. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $20.00 plus $1.00 for every foot in length. *Example, a COT-30 would be $ 20.00 + $ 30.00= $50.00 total. COT COT-(L*) $ 20.00+$1 foot*

COE Cable, Output - Extender
Extends the connection between the OCT and Power Interface. Uses 8723 cable. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $30.00 plus $1.00 for every foot in length. *Example, a COE-40 would be $ 30.00 + $ 40.00= $ 70.00 total. COE COE-(L*) $30.00+ $ 1.00/foot*

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Conditioner History

The Fractomat provided conditioning for two gauge signals. The various versions were designed and supported by Bob Churchill, who shared employment with Hartman at Research Inc./MTS Systems Corporation and Hartrun Corporation. The conditioner named the Fractomat (Photo at left) was offered for sale with gauges by Hartman's company, Hartrun Corporation.

In the Fractomat, constant current through the gauge produces a voltage proportional to crack length which is amplified and offset to compensate for the zero voltage produced by the gauge initial resistances. The 10 volt range signal voltage is the analog of crack length is then is sent to recording and control electronics. An operator selection of either the immediate (fast) voltage or a peak sensed voltage can be made to accommodate the fluctuations caused by cycling ( which reduces the signal amplitude as the load is reduced in each fatigue cycle.) Many other combinations of signal manipulation are provided. These combinations were offered before the current day data acquisition systems which offer so many user programmable manipulations of crack data in error free digital computation.

The Fractomat differs from the Power Interface in that the individual gauge information is stored in the Fractomat. The operator selects the settings for the gauge to be used. The constant current magnitude was operator programmable unlike the Power Interface which uses only a single current value and accommodates various gauges with a wide range of amplification. While providing operator convenience, there was little provision for new gauges to be added. In many cases, especially with DCB gauges, hardware modifications were made to the Fractomat to accommodate the new gauge. The Fractomat also provided for offsetting the zero initial gauge resistance.

Although no longer produced or serviced, Fractomats are still used.

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Identification	Description	Model Number	Part Number	Price
Power Interface Basic	Four channel conditioner for all crack gauges sold by Teksym Corporation, Fast output ( not integrated) only, no peak sensing.	PI 4	PI 4	$5995.00
Power interface with Peak	Four channel conditioner for all crack gauges sold by Teksym Corporation, Four Fast outputs (not integrated) and four simultaneous Peak outputs	PI 5	PI 5	$ 7995.00
Terminator	Resistive load to properly terminate Power Interface (PI 4 or PI 5) inputs	PIT	PIT	$205
Gauge Calibrator	An enclosed 30 mm gauge, resistor trimmed to the median resistance of 30 mm gauges. This calibrator is used to set the excitation current and to verify operation when troubleshooting.	GC	GC 30	$ 299.00
CIT Cable, Input - Test	Connects the Test Specimen gauge to any input channel of the Power Interface. Compatible with all Teksym crack gauges. Also compatible with CIE to extend the distance between the test gauge and Power Interface. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $20.00 plus $1.00 for every foot in length. * Example, a CIT-30 would be $ 20.00 + $ 30.00= $50.00 total.	CIT	CIT-(L*)	$ 20.00+$1 foot*
CIE Cable, Input - Extender	Extends the connection between the CIT and Power Interface. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $30.00 plus $1.00 for every foot in length. *Example, an ICE-40 would be $ 30.00 + $ 40.00= $ 70.00 total.	CIE	CIE-(L*)	$30.00+ $ 1.00/foot*
COT Cable, Output Cable - Test	Connects User's Data acquisition (DAQ) inputs to any channel Fast and peak outputs from the Power Interface. Uses 8723 cable. Also compatible with COE which extends the distance between the DAQ and Power Interface. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $20.00 plus $1.00 for every foot in length. *Example, a COT-30 would be $ 20.00 + $ 30.00= $50.00 total.	COT	COT-(L*)	$ 20.00+$1 foot*
COE Cable, Output - Extender	Extends the connection between the OCT and Power Interface. Uses 8723 cable. The Part number must have last digit(s) identify the length of the cable in feet. Total cable cost will be $30.00 plus $1.00 for every foot in length. *Example, a COE-40 would be $ 30.00 + $ 40.00= $ 70.00 total.	COE	COE-(L*)	$30.00+ $ 1.00/foot*

The maximum current produced in any GaugeLink™ external circuit is 50 ma.