The presentation describes the use of Ohmmeters in Industries having Flexible Manufacturing System. The classification of ohmmeters - Megohmmeters and Micro-ohmmeters. It's obvious that ohmmeters available and used today are of digital type. It was a seminar topic in Flexible Manufacturing System given to us.

1. Seminar Topic
Ohmmeter Sensor
Flexible Manufacturing System
Karan Prajapati 11BME083
Yudhishthir Ramnani 11BME084
(7th Semester, Mechanical Engineering, School of Technology)
1

2. Introduction
 An ohmmeter is an electrical instrument that
measures electrical resistance.
 Ohmmeter has an electronic circuit that passes a constant
current (I) through the resistance, and another circuit that
measures the voltage (V) across the resistance.
 Types
 Micro-ohmmeter
 Megohmmeter
 Micro-ohmmeters make low resistance measurements.
 Megohmmeters measure large values of resistance.
2

3. Main Specification
3
 Current leakage - the rate at which current flows
through a ground conductor and is borne away safely.
 Resistance range - measures a material’s opposition to
the flow of electric current.
 Test time - the time required to complete the test.

4. Megohmmeter
 Also known as megger.
 The prefix "meg" describes a
numerical value of 1,000,000.
 An electrical test instrument designed
to test extremely high resistances by
producing a DC (direct current)
voltage of between 300 and 15,000
volts, supplied at low current values.
 Breakdown strength of Electrical
Insulation.
4

5. Application
5
 To test the insulation resistance of wires, cables,
transformers, and electrical motors. Others are used to
verify that devices such as aircraft fuel pumps meets
manufacturer IR specifications.
 Megohmmeters are also used to test the insulation-resistance
of cable reels, rectifiers, solid-state diodes
and other electrical components.

6. 6

7. Micro-ohmmeter
 Measure low value of resistance.
 Require low value of voltage to be
applied.
 Except, all the working principles as
of Megohmmeters.
 Having higher accuracy than
Megohmmeters.
7

8. Application
8
 Aerospace metallic coating resistance measurement
 Winding resistance measurement of motors and transformers
 Bonding verification on earth/ground systems
 Weld joint integrity verification
 Contact resistance measurement of breakers and switch-gear
 Aircraft and rail bonding checks
 Wire to terminal connections and resistance checks
 Battery strap resistance checks
 Cable joint and bus bar connection checks
 Mechanical bond tests

9. 9

10. Reference
10
 http://en.wikipedia.org/wiki/Ohmmeter
 http://www.edgefx.in/ohmmeter-circuit-and-types-of-ohmmeters/
 http://www.ehow.com/how_5202652_use-megohmmeter.
html
 ftp://pti.kpi.ua/pub/electric/Microchip/disc1/download/a
ppnote/devspec/16c5x/00512e.pdf
 http://www.prolexdesign.com/images/evohmmeter.jpg
 http://www.wisegeek.com/what-is-a-megohmmeter.htm