Inst ToolsInst ToolsInst Tools
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Search
  • Books
  • Software
  • Projects
  • Process
  • Tools
  • Basics
  • Formula
  • Power Plant
  • Root Cause Analysis
  • Electrical Basics
  • Animation
  • Standards
  • 4-20 mA Course
  • Siemens PLC Course
Reading: Why we use NAMUR Output Sensor?
Share
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • Design
  • PLC
  • Interview
  • Control System
Search
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Instrumentation Design > Why we use NAMUR Output Sensor?

Why we use NAMUR Output Sensor?

Last updated: November 10, 2017 4:08 pm
Editorial Staff
Instrumentation Design
No Comments
Share
5 Min Read
SHARE

Proximity sensors and encoders can have NAMUR output

NAMUR is a type of sensor output that gives an on or off indication.  There are different reasons why you may need a NAMUR sensor.  I will go through some of them here.

First, some information about NAMUR. NAMUR is a German acronym for (normenarbeitsgemeinschaft für Mess- und Regeltechnik in der Chemischen Industrie).  This translates to: Standardization Association for Measurement and Control in Chemical Industries.  A NAMUR sensor is a non-amplified sensor that supplies two different signal levels depending upon switch state.  These signal levels are low-level current. A logic interface circuit, controller, PLC, DCS, or intrinsically safe (IS) barrier is needed to read these current levels.  A NAMUR output sensor is required in installations where special safety measures are necessary (locations with explosion hazard, or personal safety).  The standards for NAMUR output sensors are EN 60947-5-6:2000 and IEC 60947-5-6:1999.

Magnetic NAMUR sensor
A NAMUR output sensor can be normally open or normally closed, but usually, it’s normally closed.  This output is solid state, so there will be some current level on the output whether it’s on or off.  When you look at a NAMUR output sensor data sheet, it will list nominal voltage (8.2 V), load (1 k ohm), and current for measuring plate detected (<1 mA) and not detected (>2.2 mA) (for normally closed output).  Because of the low-current switching level, you’ll need an amplifier or an input that is designed specifically for NAMUR.  Although the sensor may be able to handle a range of voltages (7 VDC to 12 VDC or 5 VDC to 25 VDC), the voltage level should be at 8.2 VDC with 1k ohm resistance as the load.

Proximity sensors and encoders can have NAMUR output.  Some of the specific types of proximity sensors that have NAMUR output are capacitive, inductive, magnetic, and photoelectric sensors.  Depending on the application, you could need any one of these products to detect your target, but if they meet the NAMUR standards, the output would be the same.

The NAMUR output products that have Ex ia (intrinsic safety) approvals can be installed in hazardous (classified) locations, such as Class I, II, III; Division 1, 2; and Zone 0, Zone 1, Zone 2 areas, as long as an approved intrinsically safe (IS) input or barrier is used with the NAMUR output product.  The Zonal protection is usually for European and Class, Division is for North America.  Some approval types are ATEX, FM, UL, IEC, CENELEC, TUV, PTB, and CSA.

Also Read: How to Select a Inductive Proximity Sensor

Prevention is the protection principle for intrinsic safety. It limits current so that the current is not capable of causing ignition in hazardous atmospheres. The other protection methods are containment (explosion-proof or flame-proof enclosure) andsegregation (purging, pressurization, encapsulation, or oil filled).  Using intrinsic safety has its advantages: there are no special cables required or expensive explosion-proof conduit; it’s safe for personnel and suitable for all area classifications (Class I, II, III, Division 1, 2 and Zone 0, 1, 2).

Barrier & Sensor Connection with NAMUR
If personal safety is needed, there are versions of the NAMUR output that are also fail-safe and have a SIL3 rating (with the appropriate amplifier).  A fail-safe output ensures that if there is a failure, the output will sense a problem and fail only in the safe mode.  With this NAMUR fail-safe output, you will also need the fail-safe-rated input or amplifier.  This amplifier could be dual rated for personal safety and classified hazardous locations for gas, dust, or fibers.  With this fail-safe sensor and amplifier, this “system” would have SIL3.

Usually, NAMUR output products (which include encoders and proximity sensors) are used in classified hazardous location areas which have explosive gas, dust, or fibers present.  The fail-safe NAMUR output sensor is used where there is a personal safety hazard to protect personnel when they are working at or near the equipment.  A fail-safe NAMUR version with the appropriate intrinsically/fail-safe barrier can provide both explosion hazard and personal safety protection.

Source : P & F

Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address
You've successfully subscribed !

Continue Reading

Orifice Flow Meters: Detailed Specifications
Solenoid Valves Selection Guidelines
Detail Design Engineering Competency Aspects
What is Instrument DataSheet ?
How to Select a Conductivity Meter
Instrument Panel Cooling Efficiency Enhancement
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
Leave a Comment

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay Connected

128.3kFollowersLike
69.1kFollowersFollow
210kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

Thermowell Design Guidelines
Location of Measurement Displays
Motor Control Center (MCC) Signal Interface Termination (SIT)
Diaphragm Seal Material Selection
Transmitter Minimum Span, Accuracy & Turndown
Tagging Philosophy for Junction Box, Cable, and Cable Drum
% of Reading vs. % of Full Scale Accuracy
How to Calculate Transmitter Performance and Calibration Frequency?

Keep Learning

Field Instruments Scaling and Unit Conversions

Field Instruments Scaling and Unit Conversions

Hammer Effect in Gauges

What is Hammer Effect in Gauges ?

Insulation of Thermowell

Facts on Thermowell Insulation Thickness

Impulse Line Problems

What are Impulse Lines? – Impulse Line Problems & Solutions

Kv-value of a valve is determined by a standardised test

Calculate Flow Coefficient Kv of Solenoid Valve

Instrument Process Datasheet

Why is an Instrument Process Datasheet Required?

Basics of Cable Shields

Basics of Cable Shields

Instrumentation Books Free Download

Instrumentation Books Download

Learn More

How to use PLC With SQL Database

How to use PLC with SQL Database? – Basics & Tutorials

Difference Between Optical Fibre and Coaxial Cable

Difference Between Optical Fibre and Coaxial Cable

Pressure Transmitter Working Principle

Gage and Absolute Pressure Transmitters Principle

Pull-up switch circuit.

Pull Up and Pull Down Switch Circuits

DC Circuit

Main differences between Sinking and Sourcing Circuits

Mathematical Models of Physical Systems

Block diagram Algebra Objective Questions

Direct digital control principle

Direct Digital Control (DDC) Systems

Ultrasonic Thickness Gauge

How to Use a Paint Thickness Gauge?

Menu

  • About
  • Privacy Policy
  • Copyright

Quick Links

  • Learn PLC
  • Helping Hand
  • Part Time Job

YouTube Subscribe

Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Welcome Back!

Sign in to your account

Username or Email Address
Password

Lost your password?