constant voltage vs constant current power supply?

Question

what are the differences between constant voltage and constant current power supply?
i really have doubt about constant current power supply, as i know current produced in a circuit may be varied according to it's load. somebody can help me??

Answer 1

The terms are self explanatory. Constant current will vary the voltage to maintain constant current regardless of load impedance. Constant voltage will maintain constant voltage regardless of load current. If you had a power supply which could maintain an output of one volt no matter what the load is, it could supply all the world's energy needs, because theoretically it would supply as much current as necessary to maintain an output of one volt. So, there are practical limitations to constant current and constant voltage power supplies; their output is constant only up to a certain limit.

Answer 2

Constant Current Vs Constant Voltage

Answer 3

Constant Current Power Supply

Answer 4

A constant current power supply is really an ordinary power supply with a current limiter. It is used for devices that would grab too much current if you just put a voltage in.

In practise you would have high voltage and what the power supply will actually do is vary the voltage to get to the current that you set. For an ideal power suply the voltage will approach infinity as you increase the resistance of the load.

For a real PSU when it gets to its maximum voltage then current will drop.

Answer 5

Every power supply can be modeled either as a Thevenin voltage source or Norton current source.

The Thevenin model has an ideal voltage source in series with a resistor. The resistor value depends on the physical design of the power supply. An ideal voltage source would have a resistor of 0 Ohms in series. This means, no mater what the external load is, there will be no voltage drop as (any current)*(0 Ohms)=0 Voltage drop.
Of course, real power supplies have non zero output resistances, so the voltage delivered depends on the load. The smaller the output resistance (or impedance), the better the power supply is.
Similar analysis can be made for the case of current source.

Answer 6

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RE:
constant voltage vs constant current power supply?
what are the differences between constant voltage and constant current power supply?
i really have doubt about constant current power supply, as i know current produced in a circuit may be varied according to it's load. somebody can help me??

Answer 7

Constant current sources are less common.
common application was the use of a constant current transformer to drive a series street lighting circuit
(Used in the past for arc and incandescent lighting applications) These circuits could deliver several
kilovolts or more if the circuit were to be opened. The lamps had devices in the circuit across each lamp so
the normal 120 or 240 volts across the lamp would not have any effect, but the opening of a filament would
cause the high voltage to appear across that lamp. The device would effectively short-circuit the lamp,
maintaining circuit continuity. This principle is used in todays Christmas decorations, where 25 to 50 series
connected low voltage bulbs have built in shunts that will conduct when full line voltage appears across the
open bulb, maintaining continuity of the circuit and hopefully avoiding the job of searching for the
defective lamp

Answer 8

This is a common question as it relates to a DC motor. The amperage (or power) is directly related to the work that the motor is doing (force over time). The voltage, on the other hand, relates to the speed of the motor.

If a huge load is put on a conveyor belt with an undersized DC motor, and if that motor is voltage controlled, it will try to maintain that voltage (speed) even if it draws a dangerous amount of current to keep the conveyor going. It could try to do a lot more work than it was designed to do. The motor is likely to burn out.

On the other hand, if the conveyor belt is controlled through amperage and there is no load (or little work and little friction) the conveyor belt will speed up to a dangerous speed until the motor reaches it's specified amperage.

In reality, motor speed is often controlled through feedback loops that can include current (amperage), voltage, and/or a tachometer for speed. The computers are called controllers and have analog and or digital inputs and outputs. GE is in this field as was Allen Bradley and Reliance Electric.

Answer 9

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If the motor is operating near full load, the current increases by 3% to 4% and the power factor decreases by about 12%.

Answer 10

voltage is a pushing force and the current is a electron flow..voltage is not gana changed whatever your load is but current will,,it varies depends on the load .hope it helps you this cos its what it this..