How To Reduce Current Without Affecting the Voltage?

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Current is the flow of electrical charges through a certain area in a specific time; the voltage and current can be directly proportional when the power is constant.

However, the current can be reduced to serve certain purposes while the voltage is not affected; for example, you can use multiple techniques like fuses, resistors, circuit breakers, thermistors, transistors, or diodes. You can reduce or limit the current in electrical circuits.

How Do I Reduce Current Without Affecting the Voltage?

To reduce the current or limit it in an electrical circuit without affecting the voltage, you can use multiple techniques like fuses, resistors, circuit breakers, thermistors, transistors, or diodes.

You can reduce or limit the current in electrical circuits to protect the components of the circuit from getting overloaded, or you can reduce the current to a certain limit, where if the current exceeds this limit, the protection method is activated.

The current reducing components can differ according to several things, for example, response time, the amount of current, the sensitivity of the circuit, or the causes of overcurrent.

For example, an overcurrent can happen due to short circuit cases in some components connected to the electrical circuit, such as transistors, diodes, transformers, or capacitors. In addition, external components cause the circuit to overload, which generates an excessive current in the circuit.

Current Reducing Components

1). Resistors and Fuses

  • Resistors
    They are usually found in any electrical circuit; they are connected to the circuits in many ways, such as parallel and series connections. The resistors always obey Ohm’s law ( V = IR ), where R refers to the resistance of the circuit, V is the voltage of the power supply, and I is the total current passing through the circuit. When you connect a resistor to an electrical circuit, the current is decreased according to the value of the resistor. If you connect more resistors, the current continues to decrease. The electric current is inversely proportional to the resistance in the circuit, and the voltage stays constant regardless of the number of the resistors connected.
  • Fuses
    They are used to limit the current passing through the circuit; each fuse has a certain limit for the current; if the current exceeds this limit, the fuse blows, causing an opening in the circuit; as a result, the flow of the current stops. You can use fuses to limit the current passing through, so if you want the circuit to always keep the current value under 5 amperes, you can use a fuse that blows if the current exceeds 5 amperes. This way, you can control the current without affecting the voltage and protect the circuit’s components from overloading.

2). Circuit Breakers
The circuit breakers protect the electric circuit from overcurrent and heavy loads caused by excess currents. You can use breakers to limit the current to a certain value; if the current exceeds this limit, the breaker will trip and cut the circuit’s power. The downside of breakers is their response time; they act slowly and are not too sensitive.
3). Thermistors
Not all thermistors reduce the current passing through an electrical circuit; the negative temperature coefficient ones are used for this task. The NTC reduces the initial amount of current generated through the circuit when it’s connected to the power supply. When the temperature is high, the negative temperature coefficient thermistors have low resistance; meanwhile, they have high resistance when the temperature is low. Therefore, when the current starts flowing, the temperature starts to increase, which lowers the resistance of the NTC to a certain value, which allows only a certain amount of current to pass through.
4). Diodes and Transformers
When the circuit uses a regulated power supply, they use active components to reduce or limit the current passing through. The active components have many types, such as diodes, transistors, or integrated circuits; they are used, especially for sensitive circuits. They either cut the circuit’s power or reduce the current; this can be applied to the whole circuit or the shorted part only.
5). Current Limiting Diodes
Constant current or current limiting diodes CLD is used to reduce or limit current in electrical circuits over a wide range of voltages. They consist of a JFET, two terminals, and a gate shorted to the source. The current is kept limited without affecting the voltage even if the voltage varies; this method can be used in Zener diodes when limiting a voltage.

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Why Isn’t Voltage Not Affected When Reducing a Current Using a Resistor?

Because voltage is the power or the pressure applied to the electrical charges to pass through a certain path, the pressure stays the same even if the electrical charges are reduced.

So their number has decreased, but their pressure is constant, meanwhile, the electrical charges or the current are affected by the resistance of the resistor because the resistance represents a physical obstacle for the electrical charges.

Therefore, their motion is affected and their number. The lost charges are converted into heat energy due to the resistance they are facing in the resistor. The resistance has an inversely proportional relationship with the current, so if you increase the amount of resistance, the current decreases, but the voltage stays constant.

Should the Current of a Power Supply Be Reduced if It’s More Than What You Need?

No, you should not care about the current supplied by the voltage source if it exceeds what you need. However, before connecting a component to a voltage source, you should consider the voltage.

For example, if you use a component that requires a certain amount of volts and connects it to a source that supplies greater voltage, the component will be forced to draw more current than what it’s supposed to draw, as a result, the component will be destroyed.

Therefore, you should always consider the voltage, not the current, when connecting a component to a power source. If the voltage is suitable, the component will only draw the current it needs even if the current supplied is greater.

Conclusion

To sum up, you can reduce the current in an electrical circuit through many techniques, for example:

  • Resistors and Fuses.
  • Circuit Breakers.
  • Thermistors.
  • Diodes and Transformers.
  • Current Limiting Diodes.

You can reduce or limit the current in electrical circuits to protect the components of the circuit from getting overloaded, or you can reduce the current to a certain limit, where if the current exceeds this limit, the protection method is activated.

The current reducing components can differ according to several things, for example, response time, the amount of current, the sensitivity of the circuit, or the causes of overcurrent.

For example, an overcurrent can happen due to short circuit cases in some components connected to the electrical circuit, such as transistors, diodes, transformers, or capacitors. In addition, external components cause the circuit to overload, which generates an excessive current in the circuit.

The voltage is not affected by the resistors when reducing a current because the voltage is the power or the pressure applied to the electrical charges to pass through a certain path. Hence, the pressure stays the same even if the electrical charges are reduced, their number has decreased, but their pressure is constant.

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