A resistor is used to restrict the flow of electric current in a circuit. It can also be used to reduce the voltage level in the circuit. A resistor has a huge variety of uses. It is a major component of any electric circuit. It is a passive component. Resistors may have either fixed or variable resistance. A bleeder resistor is basically a type of resistor which is connected across a capacitor in a circuit. It is basically used to drain out the excess charge from the capacitor. It is mainly used for safety purposes. It can be used to maintain a constant voltage level across the circuit.
What is Bleeder Resistor?
A bleeder resistor is mainly used for safety purposes. It is a type of register that is connected to a high voltage power supply circuit in a parallel connection. The purpose of this connection set up to discharge the excess electric charge which is stored in the filter capacitor even after we turn off the device. By doing so, we reduce the chances of an electric shock. Sometimes, it so happens that even after switching off the device, a person may get an electric shock. This happens because of the leftover charges in the capacitor of the device. Bleeder register is used to prevent such accidents from happening. It is a specialized resistor which is specially used to discharge the capacitor after the device has been disconnected from the main power supply.
Bleeder Resistor Circuit
In order to understand the functioning of a bleeder resistor, it is very important to have a clear vision of the bleeder resistor circuit.
The given circuit represents a bleeder resistor. Here, the power supply is given through a rectifier. The output is pulsating DC. So, we have also connected a filter circuit in our arrangement.
Role in Power Supply
When we connect our circuit to the main power supply, the capacitor of the filter gets charged. The charging process continues until it reaches its peak value. When we disconnect the power supply, the This excess charge can give an electric shock to anyone who touches the circuit immediately after it has been disconnected from the circuit. So, we need the bleeder resistor to discharge the capacitor. After the circuit has been disconnected from the power supply, we have to connect the bleeder resistor in parallel to the circuit. This will help in the discharging process.
How to Choose a Bleeder Resistor?
Choosing a bleeder resistor is not an easy task. There are various factors that we need to keep in mind while choosing a bleeder register. Some of these factors have been mentioned below:
‘Vt’ is the momentary voltage across the capacitor
‘R’ is the resistance for discharge
‘𝐕u’ is the primary voltage
‘t’ is the moment recharge
‘C’ is the capacitance of the capacitor
All these factors can be represented in the form of an equation
Vt = 𝐕u * 𝒆(−𝒕/𝑹𝑪)
From the equation, we can see that lower the value of the resistance, quicker will we be able to attend the safe voltage. However, there will be some amount of misuse of power during this operation.
Functions of the Bleeder Resistor
The functions of a bleeder resistor have been mentioned below:
It can be used for safety purposes
A bleeder register mainly acts as a safety device and prevents people from getting an electric shock. It does so by discharging the capacitors of a device after the device has been turned off.
It can act as a voltage divider
This is another major advantage of a bleeder resistor. It can act as a voltage divider. If we want our equipment to provide two or more voltage supplies, then we can tap the device and the bleeder register can play the role of 2, 3 or 4 resistors which have been connected together in a series connection.
It can be used as a voltage regulator
Bleeder resistors can play the role of the voltage regulator and can be used for better voltage regulation. Voltage regulation is basically the ratio of the difference between no-load voltage and full load voltage to the full load voltage. If we can increase the value of the numerator, then the voltage regulation will improve.
To achieve that, we connect the bleeder resistor in parallel to the capacitor of the filter circuit and the load register. This will lead to a voltage drop across the bleeder register as well as across the load register. Even if there was no load register, there will be some amount of voltage drop in the circuit. In this way, a bleeder resistor can act as a voltage regulator.
1). What is bleeder current?
Bleeder current is referred to as the current which is continuously drawn from a voltage source to produce a voltage drop across a resistor. Its main function is to lessen the effect of load changes. It is associated with a bleeder resistor.
2). What is the purpose of a bleed resistor on a start capacitor?
After the start capacitor has been removed from the circuit, the bleeder register can be used to remove the residual voltage from it. It does so by discharging the capacitor. Thereby it is also referred to as the start capacitor resistor.
3). Do resistors have capacitance?
Yes, registers do have a capacitance. However, this capacitance is an unwanted property and is often referred to as a parasitic property. The capacitance of a resistor is easily disregarded in the case of DC circuits but it can have a significant effect in the case of certain high-frequency AC circuits.
4). What’s the difference between resistor and capacitor?
Both resistors and capacitors play the role of passive components in an electric circuit. However, they have significant differences between them. The difference between a resistor and a capacitor has been mentioned below:
- A register is one such device which opposes the flow of electric current in a circuit and a capacitor is a device that is meant to store electric charge.
- The resistance of a resistor is calculated using the formula R=V/I while the capacitance of a capacitor is calculated using the formula C=Q/V.
- The unit of capacitance is farad to while the unit of resistance is the ohm.
- Capacitors are used in filter blocking, waveform generation, etc. while registers are used in radio frequency and various logic circuits.
5). How does a resistor affect a capacitor?
A resistor can reduce the amount of electric charge flowing in a capacitor. As a result, it can also reduce the rate of charging or discharging of a capacitor. Thus we can say that a resistor can affect the moderation of charging and discharging of a capacitor.
Please refer to this link to know more about Wire Wound Resistor.
As we can see, the bleeder resistor is an extremely important component of an electric circuit. It can be used to prevent various accidents and can also be used for voltage regulation. In what other ways do you think the bleeder resistor can benefit the society at large?