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
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: Zener Diode Barrier Principle
Share
Notification Show More
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
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Control Systems > Zener Diode Barrier Principle

Zener Diode Barrier Principle

Last updated: June 22, 2019 12:47 pm
Editorial Staff
Control Systems
No Comments
Share
3 Min Read
SHARE

The zener diode barrier works by diverting potentially dangerous energy to ground before it can reach the hazardous area.

Contents
Zener Diode Barrier PrincipleGrounding :

Zener Diode Barrier Principle

zener diode barrier

The zener diodes limit the fault voltage to the hazardous area. There are two such diodes for redundancy. The series resistor limits current to the hazardous area, and is considered an infallible component.

The arrow in above Figure  shows the resultant path if excess current enters the barrier as a result of excess voltage input from the instrument.

Since a zener barrier is powered by the loop and it has a current limiting resistor, it has a voltage drop across it. This barrier, in addition to protecting against dangerous energy entering the hazardous area, must allow the loop to function normally.

Example :

The example in Below Figure, shows a 24 V, 4-20 mA transmitter loop. In this example, the sum of the voltage drops around the loop can be calculated and verified that they are less than 24 V.

Instead, since the maximum resistance of the barrier is specified (RMAX END TO END), Ohm’s law is used (V = IR) to calculate the total resistance available in the loop. Either method (loop voltage or loop resistance) works identically.

What we are trying to decide is whether or not the resistance of the barrier will adversely affect the loop.

Zener Barrier Protection

Resistance of zener barrier adversely affects this 24V, 4-20mA transmitter loop ? Not, if it is less than 340 Ω

Grounding :

When using zener barriers, the dangerous energy is diverted to ground. Therefore, it is important to ensure a high quality intrinsic safety ground.

In fact, because this grounding is so critical, two separate ground connections from each barriers are recommended, each with a resistance of less than 1 ohm.

The following rules should be adhered to for I.S. grounding:

  1. Since zener diode barriers work by diverting fault currents, they must have a good quality ground.
  2. The impedance of the conductor from the barrier ground bus to the ground connection should be less than 1 ohm.
  3. Follow local codes.
  4. Ground cables should be insulated.
  5. Ground cables should be protected mechanically if there is a risk of damage.
  6. Ground cable should be an uninterrupted run to the nearest high integrity earth point.
  7. Redundant cables are advisable.
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

Why Bias used in Proportional Controller ?
Voting Concept in Package Safety System
Stroke Checking Procedure for GCV, SRV, IGV, and LFBV
4-20 mA Loop Splitter
How a 4-20mA Transmitter Works?
Electrical Drives – Modes, Types, Speed Control Applications
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
208kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

What is a Network Connector? – Types of Connectors
How to Write a Program in Ecostruxure Machine Expert HVAC Software?
Interposing Relay Panel (IRP) – Wiring and Testing Requirements
Motor Control using Modbus Communication and Hardwired Signals
4-20 mA Transmitter Wiring Types : 2-Wire, 3-Wire, 4-Wire
What is Open Telemetry? – Principles and Benefits
What is a Control Panel and its types?
Fundamental Motion Control Commands

Keep Learning

Feed forward example

What is Feedforward Control ?

Proportional Band example

Why Offset in Proportional Controller ?

MODBUS ASCII Communication Protocol Explained

MODBUS ASCII Communication Protocol Explained

2-wire loop-powered transmitter

Loop Controller HART Signal Noise

Design Process Control & Safety Systems

Design View of Supplying Process Control and Safety Systems

Four Wire Current Loop

4-wire Transmitters Current Loops

Basic Concepts of the Safety Relay

Basic Concepts of the Safety Relay

Single Loop Control

Cascade Control Principle

Learn More

Applications of SCADA

Motor Clock Wise Operation using PLC

CW and CCW Operation of Motor from Same Push button

Resistor-Color-Code-Chart

Resistor Color Code Animation

PLC Program using START & STOP Buttons

PLC Program using START and STOP Buttons

Reactor Top lid lapped

Urea Reactor Top Bolted Plug developed Leaks

Procedure For reading or searching the tag number in Siemens PLC

Procedure for Reading or Searching the Tag number in Siemens PLC

Structured Text PLC Program for Sequential Process Data Storage

Structured Text PLC Code for Sequential Process Data Storage

Two-Conveyor PLC Control System

Basic Conveyor System for Product Handling in Omron PLC

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?