Ramp Section of a DC drive....

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This section of the electronics in a dc drive makes it possible to accelerate and decelerate the dc motor as per desired acceleration and deceleration rates. Two adjustments called Ramp UP and Ramp Down times are normally made avaialbe to the user. Typically values from zero to 120 seconds are possible. The circuit is normally based around two operational amplifiers and capacitors to achieve the function. Shown above is a typical ramp circuit found in analog dc drives.

 

 

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Block Diagram

 

 

Ramp Circuit

 

Speed Amplifier

 

Current Amplifier

 

 Firing Circuit

 

Power Circuit

 

Types of DC drives 

 

 

 Checking Thyristor

 

Voltage feedback Vs Tacho feedback

 

Current Limit

 

Constant HP & constant Torque

 

Field Weakening

 

Using CRO 

 

 

Motor runs at full speed

 

Fuses Blow

 

Hunting in speed

 

Motor gives jerks

 

Belts vibrate

 

Speed control not satisfactory 

 

 

Speed drops on load

 

Motor overheats

 

Sparking on commutator

 

DC drives and Power Factor

  

Your comments and suggestions 

 

Drive stops all of a sudden 

 

Motor not able to drive the load

 

DC to DC isolation

 

 Motor or Drive?

 

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