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: Polarization Index (PI) Test and DA Test
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 > Electrical Basics > Polarization Index (PI) Test and DA Test

Polarization Index (PI) Test and DA Test

Polarization Index (PI) and DA Tests are used to check the insulation resistance value of insulating materials used for electrical system.

Last updated: October 17, 2023 2:06 pm
Editorial Staff
Electrical Basics
No Comments
Share
4 Min Read
SHARE

Without use of insulating material it is impossible to use electrical supply. The insulators are used to separate the conducting and non-conducting parts. The operational reliability of the insulating material is vital for making the electrical system reliable. About 98 % faults are phase to earth faults and it happens because of insulation failures.

Contents
Polarization Index (PI) TestHow PI Test is Performed?What should be the PI Value?Dielectric Absorption Ratio (DA or DAR) TestHow DAR Test is performed?Advantage of PI and DA Test

Therefore, it is very important to check the insulation resistance value of the insulating materials used for electrical system.

The very simple method to check the insulating material resistance is through measurement of the insulation resistance. The insulation resistance is checked by megger or insulation tester.

The voltage is applied between the live part and the ground part to check the insulation resistance. The insulation resistance of the insulator can be expressed with following mathematical expression.

R = V/I

Where,

R = Insulation Resistance

V = Voltage applied

I = Current passing through insulating material

Sometimes, only checking insulation resistance value using the megger is inadequate, and it does not give the healthiness of the system.

To check the insulating quality, the more advanced tests are carried out to determine the remaining useful life of the insulating material.

The followings tests are performed to check the healthiness of the insulator.

  1. Polarization Index Test
  2. Dielectric Absorption Ratio (DAR) or DA Test

Polarization Index (PI) Test

The polarization Index is nothing but the ratio of insulation resistance after 10 minutes and after 1 minute.

How PI Test is Performed?

In PI test, ratio of insulation resistance at different times after starting of test is recorded.

The DC voltage is applied between conductors and insulating part, and the insulation resistance value is recorded after 1 minute, then test is continued and the insulation resistance value after 10 minutes is recorded.

Polarization Index (PI) Test

What should be the PI Value?

The PI value of the insulator must be above 2. The more PI value shows good insulation of the insulating material.

Dielectric Absorption Ratio (DA or DAR) Test

Similar to PI test, it is the ratio test carried out to judge the quality of the insulation.

Dielectric Absorption Ratio (DA or DAR) Test is the ratio of insulation resistance after 60 seconds and 30 seconds.

DAR indicates how quickly the capacitive current becomes zero. The capacitive current in a healthy insulation system must decay within one minute.

Dielectric Absorption Ratio (DAR) or DA Test

How DAR Test is performed?

In DAR test, ratio of insulation resistance at different times after starting of test is recorded.

The voltage is applied between conducting and insulating part, and the insulation resistance value is recorded after 30 seconds, then test is continued and the insulation resistance value after 60 seconds.

Advantage of PI and DA Test

The insulation resistance decrease with increase in temperature. Thus the measured insulation resistance value may be differ for different temperature.

However, PI and DAR is the IR ratio measurement, therefore the measurement is independent of temperature.

Author: Satyadeo Vyas

If you liked this article, then please subscribe to our YouTube Channel for Instrumentation, Electrical, PLC, and SCADA video tutorials.

You can also follow us on Facebook and Twitter to receive daily updates.

Read Next:

  • Types of Electrical Wiring
  • Types of Circuit Breakers
  • Motor VFD Drive features
  • Proper Sizing of Conductors
  • What are DOL and RDOL starters?
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

Applications of Variable Frequency Drive (VFD)
What is a Bus Coupler in Electrical Panel?
Lithium-ion Battery Charging Systems
Advantages of Valve Regulated Lead Acid (VRLA) Batteries
Electric Motor Winding Temperature Sensors
Current Transformer Selection, Operation & Maintenance
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

Download Electrical Enclosure Book
Difference between AC and DC
Difference Between Contactor and Relay
Electrical Power Grid Automation
MCB vs Fuse Questions and Answers
Electric Motors Efficiency Classes
Contactor – Basics, Wiring, Connection with PLC
Electrical Cabinet Air Conditioner – Enclosure Cooling, Maintenance

Keep Learning

Motor Controls

Design and Implement Motor Control – Electrical Engineering

Types of Motor Enclosures

Types of Motor Enclosures

Top 10 Common Mistakes on Electrical Systems

Top 10 Common Mistakes on Electrical Systems

What are HP and LP Switches in HVAC

What are HP and LP Switches in HVAC?

Working of Stepper Motor

Types of Stepper Motors

Types of Industrial Relays

What is a Relay? Types of Industrial Relays

Difference Between Metering CT and Protection CT

Difference Between Metering CT and Protection CT

Semiconductor Fuse

What is a Semiconductor Fuse?

Learn More

Intrinsic Safety of Instruments

Intrinsic Safety of Instruments

Top 100 Power Systems Projects

Top 100 Power Systems Projects – Electrical Engineering

How Does a Touch Sensor Work

How Does a Touch Sensor Work?

Eddy Current

Eddy Current Working Principle Animation

WirelessHART Network Protocol

WirelessHART Network Protocol

DP type Flow Transmitter Calibration

DP type Flow Transmitter Preventive Maintenance and Calibration

What are Pressure Sensing Lines

What are Pressure Sensing Lines? – Causes of Errors in Measurement

Ground Detector Lamp Method Principle

Ground Detector Principle

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?