HP Indigo W7250 Strain Gauge Second Transfer Measurement Service and Troublesh - Page 6

Principles of Operation, Wheatstone bridge, Wheatstone bridge diagram, Strain Gauge - How It Works

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Principles of Operation The resistance change, usually measured using a Wheatstone bridge, is related to the strain by the quantity known as the gauge factor By using a Wheatstone bridge, it is possible to compensate for temperature changes The measured voltage is proportional to the strain, and given by the following formula where: ● R = resistance ● Vs = power supply ● Vgsa - power to strain gauge Wheatstone bridge: The circuit known as a Wheatstone bridge is most commonly used to determine the value of an unknown resistance to an electrical current. In a typical Wheatstone bridge, four resistors (devices that create resistance to current in a circuit) are positioned in a circuit designed in such a way that the current from a battery splits, flows through the sequence of resistors, then recombines into a single conductor, Three of these resistors have known values, one of which is variable, or adjustable. Figure 2-2 Wheatstone bridge diagram Strain Gauge - How It Works A strain gauge is a long length of conductor arranged in a zigzag pattern on a membrane, When it is stretched, its resistance increases. Strain gauges are mounted in the same direction as the strain and often in fours to form a full 'Wheatstone Bridge' 4 Chapter 2 Introduction

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Principles of Operation
The resistance change, usually measured using a Wheatstone bridge, is related to the strain by the
quantity known as the gauge factor
By using a Wheatstone bridge, it is possible to compensate for temperature changes
The measured voltage is proportional to the strain, and given by the following formula
where:
R = resistance
Vs = power supply
Vgsa — power to strain gauge
Wheatstone bridge:
The circuit known as a Wheatstone bridge is most commonly used to determine the value of an unknown
resistance to an electrical current.
In a typical Wheatstone bridge, four resistors (devices that create resistance to current in a circuit) are
positioned in a circuit designed in such a way that the current from a battery splits, flows through the
sequence of resistors, then recombines into a single conductor, Three of these resistors have known
values, one of which is variable, or adjustable.
Figure 2-2
Wheatstone bridge diagram
Strain Gauge – How It Works
A strain gauge is a long length of conductor arranged in a zigzag pattern on a membrane, When it is
stretched, its resistance increases.
Strain gauges are mounted in the same direction as the strain and often in fours to form a full
'Wheatstone Bridge'
4
Chapter 2
Introduction