Tuesday, August 22, 2023

Introduction to Series, Parallel and Series-Parallel Connections

Why Parallel Connection is Mostly Preferred over Series Connection?

The use, application and importance of series and parallel circuit connection today cannot be over emphasized. The application of a series and parallel circuit connection can be evidently seen in our homes, school halls and in our street lights. With the press of a button, all the Bobs in our sitting rooms are turned on. some refer that the bobs in their homes should have different switches.

Well, it's not a magic when more than three electric bobs or loads are controlled by one switch. A load is anything i.e. it could be an appliances, electric bobs or even ceiling fans that consume electrical energy when connected to a power supply. The electric bobs, televisions, refrigerators etc can all be referred to as a load. The bobs convert electrical energy into light and heat form of energy. Fans convert the electrical energy into mechanical energy.

The type of connection done to our ceiling fans, electric bobs will determine if they will have a common switch or not. Series circuit connection gives us the opportunity to connect more than two loads to a common switch. Street lights are a very good example of this. Parallel circuit connection makes it possible for us to connect loads to their individual switch. Both series and parallel circuit connection are good but one is mostly preferred over the other for one reason or the other. Before we talk about the reason why parallel circuit connection is preferred over series connection, let's recall what series and parallel connections are first.

Series Circuit

A series circuit is a circuit in which resistors or loads are connected end to end so that the circuit will have only one path through which electric current flows. Thus, when a number of resistors are connected in series, the effective resistance (total resistance in the circuit) is gotten by adding the individual resistance algebraically. That is to say, if we have resistors with resistance R1, R2, R3 …Rn connected in series, then;

Ref = RT = R1 + R2 + R3 + ...Rn.

In series connections, the same current flows across all the branches of the circuits, but different voltages across it thus making the resistors to have different voltages across them. Each resistor or load will experience a voltage drop. The applied voltage is equal to the sum of the voltage drop across the different parts of the circuit. Voltage drop is proportional to the resistance current being the same throughout the circuit. When loads are connected in series, the loads will tend to have a common switch. This kind of connection is employed in school halls, street lights.

Uses & Application of Series Connection

Some people connect security lights in their homes in a series, which will make them have a common switch. The problem with this kind of connection is that when a load develops a problem, the other connected system will fail. It's an all or none type of circuit connection. Till a load gets energy before it delivers it to the other and the one to deliver fails, there will be a black out.

Series circuit connections are common and greatly employed in electrical equipment. The tube filaments in small radios are usually in series. Current controlling devices are always connected in series with the device they protect. Fuses are connected in series with the device they protect, Automatic house-heating equipment has a thermostat, electromagnetic coils, and safety cut-outs connected in series with a voltage source etc.

The break in the wire, failure or removal of any single lamp will break the circuit and cause all the others to stop working as there is only one single path for current to flow into the circuit.

If more lamps are added in the series lighting circuit, they will all be reduced in brightness. because voltage are shared in series circuit. If we add more loads in a series circuit, the overvoltage drop increases, which is not a good sign for electrical appliances protection.

Series Wiring is “ALL or NONE” type wiring meaning all the appliances will work at once or all of them will disconnect if fault occurs at any one of the connected device in series circuit.

High supply voltage is needed if we need to add more load (light bulbs, electric heaters, air conditioner etc) in the series circuit. For example, if five, 220V Lamps are to be connected in Series, Than Supply Voltage would have to be: 5 x 220V = 1.1kV.

The overall series circuit resistance increases (and current decreases) when more load added in the circuit.

According to future need, only those electrical appliances should be added in the current series circuit if they have the same current rating as current are the same at each point in series circuit. However, we know that electrical appliances and devices i.e. light bulbs, fan, heater, air conditionioner etc have different current rating, therefore, they can not be connected in series circuit for smooth and efficient operation.

Less size of wire cable is required in series wiring.

We use to protect the circuit to connect fuse & circuit breakers in series with other appliances.

Series circuit don't get overhead easily due to high resistance when more load added in the circuit.

The lifespan of battery in series circuit is more as compared to parallel.

It is most simple method of electrical wiring and fault can be easily detected and repaired as compared to parallel or series-parallel wiring.

Parallel Circuit

Resistors, loads are said to be connected in parallel when the end of each of the resistors or loads have a common point or junction and the other ends are also connected to a common point or junction. Such circuits are known as parallel circuits.

Unlike the series circuit connection, when finding the total (effective) resistance in a parallel circuit, the reciprocal of the individual resistance is taken. Thus, when a number of resistances are connected in parallel, the reciprocal of the effective resistance is given by the arithmetic or algebraic sum of the reciprocal of the individual resistance.

1/Reff or 1/RT = 1/R1 + 1/R2 + 1/R3...1/Rn.

Parallel circuit connection have the same voltage flowing across all the branches of the circuits. Different resistors have their individual currents.

Uses & Application of Parallel Connection

Parallel circuit connection is very common in use. Various lamps and electrical appliances in our homes are connected in parallel so that each of the lamps or bobs and appliances can be operated independently. For us to have control over the individual lamps or loads, they have to be wired in parallel.

Each connected electrical device and appliance are independent from others. This way, switching ON / OFF a device won't affect the other appliances and their operation.

In case of breakage in the cable or removal of any lamp will not break all circuits and connected loads, in other words, other lights/lamps and electrical appliances will still work smoothly.

If more lamps are added in the parallel lighting circuits, they will not be reduced in brightness (as it happens only in series lightning circuits). Because voltage is the same at each point in a parallel circuit. In short, they get the same voltage as the source voltage.

It is possible to add more light fixtures and load points in parallel circuits according to future need as far as the circuit is not overloaded.

Adding additional devices and components will not increase the resistance but will decrease the overall resistance of the circuit, especially when high current rating devices are used such as air conditioners and electric heaters.

Parallel wiring is more reliable, safe and simple to use.

More size of cable and wire is used in parallel lighting wiring circuit.

More current needed when additional light bulb added in the parallel circuit.

Battery runs out quicker for DC installation.

The parallel wiring design is more complex as compared to series wiring.

Related Post: Which Bulb Glows Brighter When Connected in Series and Parallel & Why?

Series-Parallel Connections & Circuits

The circuit is series nor parallel in the following fig i.e. it is series-parallel circuit. The first three lamps (B1, B2 & B3) are connected in parallel while switches (S1, S2 & S3) are wired in series accordingly. B7, B8, B9 and B10 are in series with each other while they are in parallel with the first three bulbs (B1, B2 & B3) while the switches (S5 & S6) are in parallel connected with Bulb (B10). Also, bulbs (B4, B5 & B6) and switch (S7) are in series with each other while they are in parallel with (B1, B2 & B3) and so on.

As the circuit is a combination of series and parallel, we can not simplify the current, voltage, resistance and power by simple ohm's law. We have to apply different theorems like Norton's, Thevenin's, maximum power transfer theorem etc or will simplify the circuit in basic series and parallel circuits to find all those quantities.

Introduction to Series, Parallel and Series-Parallel Connections

Why Parallel Connection is Mostly Preferred over Series Connection?

The use, application and importance of series and parallel circuit connection today cannot be over emphasized. The application of a series and parallel circuit connection can be evidently seen in our homes, school halls and in our street lights. With the press of a button, all the Bobs in our sitting rooms are turned on. some refer that the bobs in their homes should have different switches.

Well, it's not a magic when more than three electric bobs or loads are controlled by one switch. A load is anything i.e. it could be an appliances, electric bobs or even ceiling fans that consume electrical energy when connected to a power supply. The electric bobs, televisions, refrigerators etc can all be referred to as a load. The bobs convert electrical energy into light and heat form of energy. Fans convert the electrical energy into mechanical energy.

The type of connection done to our ceiling fans, electric bobs will determine if they will have a common switch or not. Series circuit connection gives us the opportunity to connect more than two loads to a common switch. Street lights are a very good example of this. Parallel circuit connection makes it possible for us to connect loads to their individual switch. Both series and parallel circuit connection are good but one is mostly preferred over the other for one reason or the other. Before we talk about the reason why parallel circuit connection is preferred over series connection, let's recall what series and parallel connections are first.

Series Circuit

A series circuit is a circuit in which resistors or loads are connected end to end so that the circuit will have only one path through which electric current flows. Thus, when a number of resistors are connected in series, the effective resistance (total resistance in the circuit) is gotten by adding the individual resistance algebraically. That is to say, if we have resistors with resistance R1, R2, R3 …Rn connected in series, then;

Ref = RT = R1 + R2 + R3 + ...Rn.

In series connections, the same current flows across all the branches of the circuits, but different voltages across it thus making the resistors to have different voltages across them. Each resistor or load will experience a voltage drop. The applied voltage is equal to the sum of the voltage drop across the different parts of the circuit. Voltage drop is proportional to the resistance current being the same throughout the circuit. When loads are connected in series, the loads will tend to have a common switch. This kind of connection is employed in school halls, street lights.

Uses & Application of Series Connection

Some people connect security lights in their homes in a series, which will make them have a common switch. The problem with this kind of connection is that when a load develops a problem, the other connected system will fail. It's an all or none type of circuit connection. Till a load gets energy before it delivers it to the other and the one to deliver fails, there will be a black out.

Series circuit connections are common and greatly employed in electrical equipment. The tube filaments in small radios are usually in series. Current controlling devices are always connected in series with the device they protect. Fuses are connected in series with the device they protect, Automatic house-heating equipment has a thermostat, electromagnetic coils, and safety cut-outs connected in series with a voltage source etc.

The break in the wire, failure or removal of any single lamp will break the circuit and cause all the others to stop working as there is only one single path for current to flow into the circuit.

If more lamps are added in the series lighting circuit, they will all be reduced in brightness. because voltage are shared in series circuit. If we add more loads in a series circuit, the overvoltage drop increases, which is not a good sign for electrical appliances protection.

Series Wiring is “ALL or NONE” type wiring meaning all the appliances will work at once or all of them will disconnect if fault occurs at any one of the connected device in series circuit.

High supply voltage is needed if we need to add more load (light bulbs, electric heaters, air conditioner etc) in the series circuit. For example, if five, 220V Lamps are to be connected in Series, Than Supply Voltage would have to be: 5 x 220V = 1.1kV.

The overall series circuit resistance increases (and current decreases) when more load added in the circuit.

According to future need, only those electrical appliances should be added in the current series circuit if they have the same current rating as current are the same at each point in series circuit. However, we know that electrical appliances and devices i.e. light bulbs, fan, heater, air conditionioner etc have different current rating, therefore, they can not be connected in series circuit for smooth and efficient operation.

Less size of wire cable is required in series wiring.

We use to protect the circuit to connect fuse & circuit breakers in series with other appliances.

Series circuit don't get overhead easily due to high resistance when more load added in the circuit.

The lifespan of battery in series circuit is more as compared to parallel.

It is most simple method of electrical wiring and fault can be easily detected and repaired as compared to parallel or series-parallel wiring.

Parallel Circuit

Resistors, loads are said to be connected in parallel when the end of each of the resistors or loads have a common point or junction and the other ends are also connected to a common point or junction. Such circuits are known as parallel circuits.

Unlike the series circuit connection, when finding the total (effective) resistance in a parallel circuit, the reciprocal of the individual resistance is taken. Thus, when a number of resistances are connected in parallel, the reciprocal of the effective resistance is given by the arithmetic or algebraic sum of the reciprocal of the individual resistance.

1/Reff or 1/RT = 1/R1 + 1/R2 + 1/R3...1/Rn.

Parallel circuit connection have the same voltage flowing across all the branches of the circuits. Different resistors have their individual currents.

Uses & Application of Parallel Connection

Parallel circuit connection is very common in use. Various lamps and electrical appliances in our homes are connected in parallel so that each of the lamps or bobs and appliances can be operated independently. For us to have control over the individual lamps or loads, they have to be wired in parallel.

Each connected electrical device and appliance are independent from others. This way, switching ON / OFF a device won't affect the other appliances and their operation.

In case of breakage in the cable or removal of any lamp will not break all circuits and connected loads, in other words, other lights/lamps and electrical appliances will still work smoothly.

If more lamps are added in the parallel lighting circuits, they will not be reduced in brightness (as it happens only in series lightning circuits). Because voltage is the same at each point in a parallel circuit. In short, they get the same voltage as the source voltage.

It is possible to add more light fixtures and load points in parallel circuits according to future need as far as the circuit is not overloaded.

Adding additional devices and components will not increase the resistance but will decrease the overall resistance of the circuit, especially when high current rating devices are used such as air conditioners and electric heaters.

Parallel wiring is more reliable, safe and simple to use.

More size of cable and wire is used in parallel lighting wiring circuit.

More current needed when additional light bulb added in the parallel circuit.

Battery runs out quicker for DC installation.

The parallel wiring design is more complex as compared to series wiring.

Related Post: Which Bulb Glows Brighter When Connected in Series and Parallel & Why?

Series-Parallel Connections & Circuits

The circuit is series nor parallel in the following fig i.e. it is series-parallel circuit. The first three lamps (B1, B2 & B3) are connected in parallel while switches (S1, S2 & S3) are wired in series accordingly. B7, B8, B9 and B10 are in series with each other while they are in parallel with the first three bulbs (B1, B2 & B3) while the switches (S5 & S6) are in parallel connected with Bulb (B10). Also, bulbs (B4, B5 & B6) and switch (S7) are in series with each other while they are in parallel with (B1, B2 & B3) and so on.

As the circuit is a combination of series and parallel, we can not simplify the current, voltage, resistance and power by simple ohm's law. We have to apply different theorems like Norton's, Thevenin's, maximum power transfer theorem etc or will simplify the circuit in basic series and parallel circuits to find all those quantities.