Electrical Balance Load and Unbalance Load Example, Circuit

The polyphase electrical circuits and loads are divided into two types - 1. Balance Circuit or Balance Load and 2. Unbalance Circuit or Unbalance Load. In this article, we are going to learn everything about balanced load, unbalanced load, balance circuit, and unbalanced circuit. 

Balance Circuit

The balance and unbalance concept comes with a three-phase or polyphase system. So, in a three-phase electric circuit where voltage and current in all three phases are identical or equal is called a Balance Circuit.

The main characteristics of a balanced circuit are,

1. The magnitude of voltage in each phase is identical.

2. Phase differences in each phase are equal.

3. The current in each phase is equal.

4. The algebraic sum of the current in each phase is equal to zero.

5. There is no ground fault or earth fault in a balanced circuit.

6. The balance circuit does not have any fault like a symmetrical fault or unsymmetrical fault.

Read Also: Transient Voltage Cause, Sources, Effects, Protection

Diagram of Balance Circuit

Here you can see a three-phase balanced circuit diagram and a phasor diagram.

Here, you can see all line voltage(voltage between phase to phase) and phase voltage(voltage between phase to neutral) are equal. Also, all line currents (the flow of current between phase to phase) and phase currents (the flow of current from phase to neutral) are identical. In the above phasor diagram, you can see the angle between all three phases is the same.

Balance Circuit Example: Overhead electrical transmission line is an example of a Balance Circuit. Mostly delta delta-connected three-phase circuits can maintain or fulfill all the characteristics of a balanced circuit. In a star-connected circuit, it is very hard to maintain balance. 

Read Also: Earth Fault Causes, Effects, Example, Explanation

Balance Load

When a three-phase load consumes an equal current in every phase, it will be called a balanced load.

The main characteristics or properties of a balanced load are,

1. They always consume identical currents in each phase.
2. They always cause a balance of phase differences between all three phases.
3. There is no leakage current flow from the load.
4. Load performance and efficiency are high.
5. It keeps the overall system healthy.

Balanced Load Example: Three-phase electric motors and electric heaters are examples of balanced load if they consume equal current or fulfill all the characteristics of balance load.

Unbalance Circuit

A three-phase circuit will be called an unbalanced circuit when the flow of current and voltage in each phase are not equal. So, the voltage imbalance, current imbalance, and phase differences make a circuit unbalanced. 

Here, the characteristics or properties of an unbalanced circuit,

1. The flow of current in each phase is not equal.

2. Voltage in each phase is different.

3. The phase differences in each phase are not identical.

4. An unbalanced circuit has a leakage current to flow.

Unbalance Circuit Example: Star-connected Electrical power distribution circuit is an example of unbalance circuit. Although it is always tried to connect single-phase load equally to all three phases, it is not exactly possible to balance.

Read Also: Ground Fault Causes, Effects, Example, Explanation

Diagram of Unbalance Circuit

Here you can see the unbalance circuit diagram.

You can see, there the flow of current in each phase are not identical. Voltage is also different.

Reasons/ Causes to Make a Circuit Unbalance

1. A symmetrical fault does not affect more to make the circuit unbalanced but an unsymmetrical fault definitely makes a power circuit or power system unbalanced.

2. Earth Leakage, Earth Fault, and Ground Fault make the circuit unbalanced.

3. When an unbalanced load is connected to a power circuit, the circuit will be unbalanced.

4. Circuit unbalance also occurs due to switching, lightning, power surges, etc. But this is for a short duration only.

Read Also: Difference between Earth Fault Relay and Earth Leakage Relay

Effects of Unbalance Circuit

1. An unbalanced circuit makes huge power loss.

2. An unbalanced circuit makes excessive heating.

3. Unbalance circuit causes to frequent tripping of the protective circuit breakers.

4. Unbalancing in the power circuit not only harms the connected load, but it also harms the generating devices also.

Unbalanced Load

When an electrical load consumes a different amount of electrical current in each phase, it is called an Unbalanced Load.

The main properties or characteristics of an Unbalance load are,

1. It consumes unequal current in each phase.
2. It causes to make voltage imbalance in a circuit.
3. It causes to flow leakage currents.
4. It can make the overall system unhealthy.
5. Load efficiency and performance decreased.

Unbalance Load Example: Faulty Three-phase motors(one or two winding burned), and faulty three-phase heaters are examples of Unbalance Loads.

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