Kobold NSD User Manual

NSD OPTICAL SWITCH OPERATION MANUAL

PRINCIPLE OF OPERATION

The optical switch operates by the principle of Snell's law: When
light moves from a medium of a given refractive index (n1) into a
second medium with refractive index (n2), both reflection and
refraction of the light may occur. An incident light ray strikes at a
point on the interface between two media of refractive indices n1
and n2. Total internal reflection is an optical phenomenon that
occurs when a ray of light strikes a medium boundary at an angle
larger than a particular critical angle with respect to the normal to
the surface. If the refractive index is lower on the other side of the
boundary, no light can pass through and all of the light is
reflected. When light crosses a boundary between materials with
different refractive indices, the light beam will be partially
refracted at the boundary surface, and partially reflected.

Optical switches operate by sensing the difference in the
refraction index between various mediums, causing different
degrees of refraction and penetration. When the liquid is not in
contact with the sensor, all transmitted light is reflected back to
the receiver. When the liquid contacts the sensor, part of the
transmitted light is reflected back to the receiver and part is
emitted into the liquid. The receiver senses this difference in
signal loss and switches accordingly.

FEATURES DIMENSIONS

1. PNP Open-Collector Output

2. Housing Material: Polysulfone or 316SS

3. Over-current & Reverse Polarity Protection

4. LED status indication

SPECIFICATIONS

1. Housing Material: Polysulfone or 316SS
Sensing Tip Material: Polysulfone

2. Protection Rating : IP68

3 Process Temperature: 14-250 °F

4. Ambient Temperature: 14-175 °F

5. Max. Operating Pressure:
Polysulfone: 140 PSIG
316SS: 560 PSIG

6. Input Power: 10-28 VDC

7. Load Current: 100mA Max.

8. Overload Current Protection: 100mA

9. Process Connection: 3/8" NPT

10. Cable: 2 m PVC Jacket, 24 AWG, 3-conductor

WIRING

APPLICATION EXAMPLE

Liquid Level Control:
In Fig.4(a), two optical switches are installed individually at the desired upper
and lower levels of the tank. When the level in the tank drops and the lower
optical switch is no longer covered by liquid, it will change state and signal the
controller to begin the filling process. Upon reaching the upper optical switch,
the switch will change state and signal the controller to stop the filling
process, thus maintaining the liquid level between the upper and lower optical
switches.

Motor Protection:
In Fig.4(b) , the optical switch is installed in the lower level of the tank to
prevent pump burnout caused by the lack of water/liquid. Avoid installation
within a corner.

CAUTIONS

 Always apply an appropriate sealing compound around the sensor

threads (PTFE Liquid or Tape is suggested) before installation

 Maximum Installation Torque: 316SS = 8 Lb-Ft, PSU = 4 Lb-Ft.
 The optical switch is not recommended for use in emulsions or phase-

change liquids

 Do not install sensor close to other infrared sources
 The tip of the optical sensor must remain at least 1.2” from any reflective

surface or physical interferences, like the tank wall (Fig.5)

 This product is not recommended for use with organic solvents or

highly viscous or coating type liquids which can remain on the lens surface

 Clean the lens periodically using appropriate methods and compatible

products

 Do not use organic solvents or scrub while cleaning to avoid scratches on the lens surface

ORDERING INFORMATION

Example: NSD- G AU P1
Housing Material:

G: Polysulfone 6: 316SS

Connection Thread:

AU: 3/8"NPT

Output Form:

P0: PNP N.C. (Dry ON) P1: PNP N.O. (Wet ON)

KOBOLD Instruments, Inc.

1801 Parkway View Drive Pittsburgh, PA 15205
phone: [phone] fax: [phone]
e-mail: [e-mail] web-site: www.koboldusa.com r1_04-2013