# Series & Parallel Circuit Comparison

Series | Parallel | |||
---|---|---|---|---|

Voltage | additive | constant | ||

Current | constant | additive | ||

Resistance | additive | additive | ||

Power | additive | additive | ||

Voltage Drop | ||||

## Series Circuits

- Closed Loop circuit with only one path where current may flow
- Used for Controls and Signaling mostly

Series Circuit Rules | |
---|---|

Rule 1 | Current total equals the current in any part of the circuit |

Rule 2 | Voltage total equals the sum of all voltages |

Rule 3 | Resistance total equals the sum of all resistances |

**Series circuit Total current: I=E _{s}/R_{t}**

**Series Circuit Calculations:**

- Determine each circuit resistors resistance
- Calculate circuit
**total resistance**- R
_{t}= R_{1}+ R_{2}+ R_{3}…

- R
- Calculate the
**current**- I = E
_{s}/ R_{t}

- I = E

### Series Circuit Summary

- Resistors are measured across
- Current is same value through all resistances
- Source voltage = Sum of all resistances voltage drops
- All resistances power consumed sum = Total power consumed by the circuit

## Parallel Circuits

- Open-Loop Circuit with more than one path for current to flow
- Resistance is additive
- Voltage Drop across each resistance is equal to the voltage drop supplied by the power source

Parallel Circuit Rules | |
---|---|

Rule 1 | Current total equals the sum of all currents in all circuit branches |

Rule 2 | Voltage total equals the sum of all voltages |

Rule 3 | Resistance total is found by applying Ohm’s Law to the total values (Rt=Et/It) NEED SUPERSCRIPT CODE Note: Total resistance is always less than the resistance of any branch. |

### 3 Methods to calculate Total Resistance in Parallel Circuits

- Equal Resistance
**R**_{t}= 1 resistor Ω / number of resistors- Note: All resistors must have same resistance

- Product-over-Sum
**R**_{t}= (R_{1}x R_{2}) / (R_{1}+ R_{2})- Note: Only uses 2 resistors per equation
- If more then 2 resistors, then use the equivalent resistance of the last 2 resistors as a ‘new’ resistance for the next equation

- Note: Only uses 2 resistors per equation

- Reciprocal
**R**_{t}= 1/_{[(1/R1) + (1/R2) + (1/R3)…]}- Note: Preferred method because this can be used for as many resistors as contained within a circuit

### Parallel Circuit Summary

- Voltage is same across each circuit component
- Total power Consumed = Sum of the Power in all branches
- R
_{t }is always less then smallest individual resistor - R
_{t}calculation = 1/_{[(1/R1) + (1/R2) + (1/R3)…]} - Has 2 or more paths for current to flow
- Total Current = is provided by Source voltage and sum of all currents in all branches

### Series-Parallel Circuit Summary

*Obtain different voltages of series circuits combined with different currents of parallel circuits*

# Power Supplies

Series-Connected | Parallel-Connected |
---|---|

voltage is additive | Voltage constant |

current constant | current increases |

### Series-connected

- voltage is additive
- current constant

### Parallel-connected

- Voltage constant
- current increases

### Series-connected Delta/Delta

- Transformer power supply, 3Ø = 3 transformers connected in series