Counter torque, voltage and current

In summary, the counter torque on a generator is required by conservation of energy and is equal to the output power divided by the rotational speed. It can be influenced by voltage, current phase shift, and load connected. The presence of a counter EMF in the generator is closely related to the counter torque, as the power in the counter EMF is what gives the counter torque.
  • #1
Idea04
194
1
When an ac generator produces high current the counter torque increases, but if voltage increases would the counter torque decrease? Is counter torque related to counter EMF?
 
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  • #2
Counter torque is required by conservation of energy. Mechanical power is equal to the product of torque times rotational speed. Torque (in n-m) times rotational speed (in radian per sec) gives power in Watts.

Thus the minimum possible counter torque on a generator is equal to the output power divided by the rotational speed. Of course the actual torque is typically somewhat greater than this due to the presence of both electrical and mechanical losses.
 
  • #3
is counter torque affected by voltage and current phase shift?
 
  • #4
Idea04 said:
is counter torque affected by voltage and current phase shift?

Yes, look at what I said above about power and counter torque. Since power can be influenced by all of those variables then the counter torque can be influenced too.
 
  • #5
"is counter torque related to counter emf?"

Consider that when voltage is induced in the armature of the generator, a connected load will draw a current that creates a magnetic field which opposes the source magnetic field (lenz' law)

The more load connected (parallel) the lower the overall resistance. The current draw increases, and the magnetic field which opposes the source field is stronger.

The counter torque is the reaction between the source field (which induces voltage in the armature) and the field created by the armature current
 
  • #6
Idea04 said:
Is counter torque related to counter EMF?
Yeah, that's actually a very pertinent question.

Not all machine models include an internal "back" EMF (induction motor for example), but for those that do (synchronous and DC machines for example) the energy flowing in/out of this internal EMF is precisely the energy being converted (from/to electrical to/from mechanical).

So yes, this counter EMF (or more particularly the power in this EMF) is extremely closely connected with the counter torque. Specifically it is this power, which when divided by the rotational speed, gives precisely the counter torque.
 

What is counter torque?

Counter torque is the opposing force or torque that acts on a rotating object. It is caused by an external force or by internal forces such as friction.

What is voltage?

Voltage is the measure of electrical potential difference between two points in an electrical circuit. It is measured in volts (V) and is represented by the symbol V.

What is current?

Current is the flow of electric charge through a conductor. It is measured in amperes (A) and is represented by the symbol I. Current can be either direct (DC) or alternating (AC).

How are counter torque, voltage, and current related?

Counter torque, voltage, and current are all related through Ohm's Law. This law states that the voltage (V) is equal to the product of the current (I) and resistance (R), or V=IR. In other words, the higher the voltage, the greater the current and the stronger the counter torque.

How can counter torque, voltage, and current be manipulated?

Counter torque, voltage, and current can be manipulated by changing the resistance in a circuit. This can be done by adding or removing resistors, or by adjusting the resistance of a variable resistor. Changing the voltage source can also affect the current and counter torque in a circuit.

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