Measure voltage, current and power in a 1-phase circuit with resistive load. (Feee)

Aim:  To measure the voltage, current, and power in a single-phase AC circuit with a purely resistive load.

 Objective

To measure the voltage, current, and power in a single-phase AC circuit with a purely resistive load.

Apparatus Required

1. AC Power Supply (Single-phase, 230V, 50Hz)
2. Resistive Load (e.g., a heating element or resistor)
3. Voltmeter (Range: 0-300V, AC)
4. Ammeter (Range: 0-10A, AC)
5. Wattmeter (Optional, Range: 0-2kW)
6. Connecting Wires

Circuit Diagram

Include a circuit diagram showing:

• The resistive load connected to the AC power supply.
• The ammeter in series with the load.
• The voltmeter connected in parallel with the load.
• (Optional) The wattmeter connected to measure power.

Theory

A single-phase AC circuit with a resistive load is one of the simplest and most fundamental types of electrical circuits. In such a circuit, the load is purely resistive, meaning it only has resistance (R) and no inductance (L) or capacitance (C). The behavior of the circuit can be described using Ohm's Law and basic AC circuit theory.

In a single-phase AC circuit with a resistive load:

1. Voltage (‘V’) is measured across the load.
2. Current (‘I’) is measured through the load.
3. Power (‘P’) is calculated as: $$P = V \times I$$
   • Since the load is purely resistive, the power factor (‘pf’) is 1.

Procedure

1. Safety Precautions:

   • Ensure all equipment is in good working condition.
   • Use proper ranges on measuring devices to avoid damage.
   • Ensure all connections are secure and insulated.

2. Circuit Setup:

   • Connect the resistive load to the AC power supply.
   • Connect the ammeter in series with the load.
   • Connect the voltmeter across the load.
   • If using a wattmeter, connect the current coil in series and the voltage coil in parallel with the load.

3. Measurement:

   • Switch on the power supply.
   • Record the voltage across the load using the voltmeter.
   • Record the current through the load using the ammeter.
   • If a wattmeter is used, note the power directly from its reading.

4. Power Calculation:

   • Calculate the power using the formula: $$P = V \times I$$

Observation Table

Sample Calculation

Suppose the measured values are:

• Voltage (‘V’) = 230V
• Current (‘I’) = 5A

Power Calculation:

$$P = V \times I = 230 \times 5 = 1150 \text{ W (Watts)}$$

Result

The measured values of voltage, current, and power for the single-phase circuit with a resistive load are as follows:

• Voltage: ______ V
• Current: ______ A
• Power: ______ W

Precautions

1. Ensure the power supply is switched off before making any connections.
2. Use measuring instruments with appropriate ranges.
3. Avoid loose connections to prevent sparking or damage.
4. Verify all connections before switching on the circuit.

Conclusion

The voltage, current, and power in the single-phase circuit with a resistive load were successfully measured, and the calculated power matched the expected value for the given load conditions.

---