Understanding series and parallel connections is one of the most important fundamentals in electrical engineering. Whether it is home wiring, electrical panels, or industrial control circuits, every system is designed using a combination of series and parallel circuits. In this guide, we will understand the difference, working principle, formulas, and practical applications of series and parallel connections.
ELECTRICAL PANEL
In any machine panel, there are 2 types of wirings- ‘Control wiring’ & ‘Power wiring’.
1. Control Wiring
Control wiring as name suggests; controls the power circuit of the machine. Control wiring has very little current at lower or equal voltage than the voltage present at power wiring side.
2. Power Wiring
Power wiring is the heavy wiring which is designed for heavy load current at higher or equal voltage than voltage at control wiring side.
In DOL Starter, which contains Contactor & thermal overload relay. The wiring which contains NO push button to start, NC push button to stop, Supply to contactor coil & NC of thermal overload relay which is used in controlling the entire circuit; is known as Control wiring. The three phase power supply from thermal overload relay to contactor & from contactor to the motor is known as Power wiring.
Every single component is connected in particular connection that is series or parallel. Like NC of stop & NO of start are connected in series while the hold NO is connected in parallel. Power wiring from thermal overload relay to contactor to electrical motor, All is connected in series.
Both the wirings control & power are shown in an image below :
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Series & Parallel connections
- All the Appliances in our premises; connected parallel to power supply so that equal voltage appear across all the appliances.
- Switch connected for ON&OFF function of the appliance; is connected in series with appliance So that current flows through the switch.
Both the above said examples are simplest one !
Series connection
In this connection, Components are connected end to end so that current remains the same through out all the connected components & Voltage get divided.
- In series, Currents remains the same throughout this connection. Current flowing through the circuit; is the total current of the circuit.
- In series, Voltage get divided. Algebraic sum of voltage drop across each component is the total voltage across the circuit.
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Parallel connection
In this connection (components with two ends ) ends of the components from the both sides are connected; so that two junction points are obtained. Voltage is being applied on these two junctions. In parallel connection voltage remains the same while current is get divided.
- Applied voltage is same across all the components Which is the total voltage of the circuit.
- The algebraic sum of current on each component is the total current of the circuit.
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Series vs Parallel Circuits (Comparison Table)
| Feature | Series Circuit | Parallel Circuit |
|---|---|---|
| Current | Same through all components | Divided among branches |
| Voltage | Split across components | Same across all components |
| Paths | Single path | Multiple paths |
| Reliability | Low | High |
| Failure effect | Entire circuit stops | Other branches continue |
| Wiring required | Less | More |
Importance of series & parallel connections
Whatever the type of Electrical circuit, series & parallel connections are always there. In next 2 discussed examples we easily understand the importance of series & parallel connections.
1. Importance in Electrical Machine panel
In bulky Electric panel, Many functions are working together. At first sight, It is quite difficult to understand.
But when we get know that how many functions are working parallel than it is get easy to observe one single function from all the parallel connection at time. Than it becomes easy to understand the panel wiring.
Any particular machine works with logics. This logic is created with in the PLC or hard wired. Series & parallel connection is very important to understand to create logical circuit.
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2.Importance of Battery connections in series & parallel connections
- When we need output of 72 VDC with capacity of 150Ah. This voltage can be achieved by connecting all the 6 batteries in series. Series connection should be connected in alternate polarity; positive with negative & negative with positive. As shown in image below:
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- When we need output of 12VDC with capacity of 900Ah. This can be achieved by connecting all the 6 batteries in parallel. Positive with Positive & Negative with Negative As shown in an image below:
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- We need output of 36VDC with capacity of 300 Ah. This can be achieved by connecting 2 set of batteries in parallel, Each set contains 3 batteries in series. As shown in an image below:
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Advantages and Disadvantages
✅ Advantages of Series Circuits
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Simple design
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Less wiring required
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Easy to analyze
❌ Disadvantages of Series Circuits
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Poor reliability
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Voltage drops across components
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Not suitable for household or industrial use
✅ Advantages of Parallel Circuits
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High reliability
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Constant voltage supply
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Suitable for domestic and industrial wiring
❌ Disadvantages of Parallel Circuits
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Requires more wiring
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Slightly complex design
Real-Life Applications
🔹 Series Circuit Applications
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Decorative lighting strings
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Voltage divider circuits
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Battery packs (for increasing voltage)
🔹 Parallel Circuit Applications
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Household wiring
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Industrial power distribution
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Street lighting systems
SUM UP
- Series & parallel connections are very important in Electrical system. From a basic switch circuit to complex logic; it plays a very important role.
- All the appliances & devices connected in our premises are connected in parallel While switching to these appliances through on-off switches is being done in series manner.
- Voltage remains the same in parallel connections while in series connections, Current remains the same.
- Current get divided in parallel connections while in series connection, Voltage get divided.
Frequently Asked Questions (FAQs)
Q. What happens to current in a series circuit?
The current remains the same through all components because there is only one path.
Q. Why does voltage divide in a series circuit?
Voltage divides according to the resistance of each component.
Q. Which circuit is safer: series or parallel?
Parallel circuits are safer and more reliable for practical use.
Q. Can series and parallel circuits be used together?
Yes. Most real electrical systems use a combination of series and parallel connections.
Q. Which circuit consumes more power?
Parallel circuits usually consume more power because each branch operates at full voltage.