Multi-Range Analog Ammeter

1 / 9

# Multi-Range Analog Ammeter - PowerPoint PPT Presentation

Multi-Range Analog Ammeter. Multi-Range Multiple Full-Scale Values Ranges less than and/or greater than the device’s full-scale value Measure 10 mA with a 0-1 mA device Analog Meter Moving-pointer Works by interaction of magnetic fields. Basic Analog Meter Movement.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Multi-Range Analog Ammeter
• Multi-Range
• Multiple Full-Scale Values
• Ranges less than and/or greater than the device’s full-scale value
• Measure 10 mA with a 0-1 mA device
• Analog Meter
• Moving-pointer
• Works by interaction of magnetic fields

ECE 201 Circuit Theory I

Basic Analog Meter Movement

ECE 201 Circuit Theory I

Interaction of Magnetic FieldsBasic DC Motor

Permanent Magnet Magnetic flux from N to S

Current into A and out of BMagnetic flux due to current

ECE 201 Circuit Theory I

Resulting CCW Rotation

Flux “Bunching”

Mechanical forces on the conductor

ECE 201 Circuit Theory I

Extending the Range of an Ammeter
• Meter movements available in standard full-scale values
• We have 0 – 1 mA
• To measure currents greater than 1 mA, we need to “divert” the extra current away from the meter using a “shunt”

ECE 201 Circuit Theory I

Calculation of the Shunt Resistor
• Ishunt = ILoad - Imeter
• Parallel combination of meter and shunt
• ImeterRmeter = IshuntRshunt
• Rshunt = Rmeter(Imeter/Ishunt)
• Need to know Rmeter !

Imeter

Ishunt

ECE 201 Circuit Theory I

• Do not connect the meter movement to any analog or digital multimeter configured as an ohmmeter!
• The internal battery will supply too much current and destroy the movement!

ECE 201 Circuit Theory I

Preliminary (Prelab) Work
• Devise a non-destructive scheme to determine the internal resistance of the meter movement.
• You may use any equipment or components (power supply, function generator, resistors, potentiometers,etc.).
• Have your method approved BEFORE you begin the experiment!

ECE 201 Circuit Theory I