Instrumentation & Measurements

Chapter 7 : 

Chapter 7 SPECIALIZED METERS: ANALOG AND DIGITAL

Lecture OutLine : 

Lecture OutLine Ohmmeters Construction Working Issues Volt-ohm –milliammeter Construction Operation Digital voltmeters Working Principle

Analog Ohmmeters : 

Analog Ohmmeters An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current. Types Series Parallel Performance issues Nonlinearity. Accuracy Battery Life Sensitivity measure Midway deflection

Scales for Different Types of OHMMETER : 

Scales for Different Types of OHMMETER

Volt-Ohm-milliammeter : 

Volt-Ohm-milliammeter Also known as analog multimeter can measure Voltage Current Resistance Meter to be used as reference Simpson 260 Series 7 Analog VOM

Simpson 260-7 : 

Simpson 260-7 SCALE

Panel : 

Panel

Other Views : 

Other Views

Simpson 260-7 Specifications : 

Simpson 260-7 Specifications DC VOLTAGE Ranges: 250mV, 1V, 2.5V, 10V, 50V, 250V, 500V, 1000V Accuracy 2% of full scale * Sensitivity 20K per volt AC VOLTAGE Ranges 2.5V, 10V, 50V, 250V, 500V, 1000V Accuracy 3% of full scale * Sensitivity 5K per volt Rated Circuit-To-Ground Voltage 1000V (AC or DC) max.

Simpson 260-7 Specifications : 

Simpson 260-7 Specifications DECIBEL 5 Ranges -20 to +50dB Reference 0dB= 1mW into 600Ω DC CURRENT Ranges 50μA, 1mA, 10mA, l00mA, 500mA, 10A Accuracy 1.5% full scale 5OμA, 2.0% of full scale, all other Voltage Drop: (Nominal) 250mV on 50μA , 1mA; 255mV on 10mA , 10A; 300mV on 100mA, 500mV on 500mA RESISTANCE Ranges Rx 1, Rx 100, Rx 10K Accuracy 2.5° of arc on Rx1, 2.0° of arc on other Maximum Indication 0-2KΩ, 0-200Ω, 0-20MΩ

Schematic : 

Schematic

Measurement : 

Measurement For DC voltage 0-250mV range Set the function switch at +DC Plug the black test lead in the __ COMMON Jack and the red lead into the +50 μAMPS / 250mV jack. Set the range switch at 50 μ AMPS (COMMON) position with 50V. Read black scale in millivolts. Schematic Panel SCALE

Measurement: : 

Measurement: DC Voltage Measurement 0-500V Set the function switch at +DC Black lead  Common , Red lead  + Set the range switch. Initially as high as possible. For 10, 50 and 250V reads directly. For 500 read 0-50 and then multiply by 100 for 2.5 range? Schematic Panel SCALE

Measurement : 

Measurement AC voltage measurement 0-2.5 upto 0-500V Set the function switch at AC. Set the range switch at one of the five range positons. Black lead  common red lead  + For 2.5 V read the scale labeled AC. For other ranges read the marking from AC scale and read the value from DC scale. Schematic Panel SCALE

Output Voltage Measurement : 

Output Voltage Measurement If the output of circuit contains DC component also and we intend to measure the AC component only. Set the function to AC. Black lead  Common, red lead  OUTPUT Set the range switch Schematic Panel SCALE Read the corresponding scale

Measurement : 

Measurement Current Measurement +10 , -10 A terminals? Reading Assignment: Operators manual, Simpson 260 (Series 7) http://www.simpson260.com/260-7/simpson_260-7m.htm http://www.simpsonelectric.com/main/index.asp?p=Download_and_Request_Literature&s=Manuals 2) Chapter 180-188