1 HVACR - Refrigeration Series and Parallel Circuits

2 Series Circuits A series circuit has one single path for current flow. The loads are arranged so current must flow through load #1, then load #2, then load #3. If the connection is broken anywhere, or if one load fails, current flow stops in the entire circuit. A series circuit has one single path for current flow. The loads are arranged so current must flow through load #1, then load #2, then load #3. If the connection is broken anywhere, or if one load fails, current flow stops in the entire circuit.

3 Series Circuits Voltage is divided by all of the loads in a series circuit. In a series circuit, as each load consumes power there will be a voltage drop. Switches and contacts are not power consuming devices and should not cause any voltage drop. Voltage is divided by all of the loads in a series circuit. In a series circuit, as each load consumes power there will be a voltage drop. Switches and contacts are not power consuming devices and should not cause any voltage drop.

4 Simple Series Circuit Diagram

5 Series Circuits Total Resistance for Series Circuit −A series circuit has only one path for current flow. −The total resistance is the sum of all the resistances in the circuit. Total Resistance for Series Circuit −A series circuit has only one path for current flow. −The total resistance is the sum of all the resistances in the circuit.

6

7 Series Circuits The resistances of a series circuit can be added for the sum of the resistances of the total circuit. For example: R1 = 10 ohms R2 = 10 ohms R3 = 20 ohms RT = 40 ohms The resistances of a series circuit can be added for the sum of the resistances of the total circuit. For example: R1 = 10 ohms R2 = 10 ohms R3 = 20 ohms RT = 40 ohms

8 Parallel Circuits A parallel circuit has more than one path for current to flow. Parallel circuits will connect several loads across the same voltage source. The current flows through each load, independent of the others. The current flow through each load is not always equal. The voltage across each load is always equal. A parallel circuit has more than one path for current to flow. Parallel circuits will connect several loads across the same voltage source. The current flows through each load, independent of the others. The current flow through each load is not always equal. The voltage across each load is always equal.

9 Parallel Circuit Diagram

10 Parallel Circuits Total resistance in a parallel circuit: −A series circuit has more than one path for current flow. −Adding additional loads will decrease the total resistance in the circuit. −The total resistance is always less than the smallest resistance in the circuit. Total resistance in a parallel circuit: −A series circuit has more than one path for current flow. −Adding additional loads will decrease the total resistance in the circuit. −The total resistance is always less than the smallest resistance in the circuit.