Page 103 - Sensors and Control Systems in Manufacturing

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T w o
Cha p te r

FIGURE 2.40 Bulk
FIGURE 2.39 Liquid level material level FIGURE 2.41 Process
detection, capacitive control, capacitive control, capacitive proximity
proximity sensor. proximity sensor. sensor.

2.5.2 Typical Applications of Capacitive Proximity Sensors
Liquid level detection (Fig. 2.39):

• Tube high/low liquid level
• Overflow limit
• Dry tank

Bulk material level control (Fig. 2.40):

• Low level limit
• Overflow limit
• Material present

Process control (Fig. 2.41):
• Product present
• Bottle fill level
• Product count

2.6 Understanding Inductive Proximity Sensors

2.6.1 Principles of Operation
An inductive proximity sensor consists of four basic elements
(Fig. 2.42):

• Sensor coil and ferrite core
• Oscillator circuit
• Detector circuit
• Solid-state output circuit