Lab Report: Testing the Performance of a Given UPS (Uninterruptible Power Supply)

1. Objective:

To test and evaluate the performance parameters of a given UPS under different load conditions, such as voltage stability, backup time, efficiency, and waveform quality.

2. Apparatus Required:

  • UPS (Uninterruptible Power Supply, 600 VA or higher)
  • Multimeter (to measure voltage and current)
  • Oscilloscope (to observe waveform quality)
  • AC power supply (230V, 50Hz)
  • Resistive load (lamps, heater, or power resistors)
  • Stop-watch (for backup time measurement)

3. Key Performance Parameters:

  1. Input and Output Voltage: Stability and regulation
  2. Output Waveform: Pure sine wave or modified sine wave
  3. Efficiency: Ratio of output power to input power
  4. Backup Time: Duration of battery supply under a given load
  5. Switching Time: Time taken to switch from mains to battery

4. Procedure:

Step 1: No-Load Test

  1. Connect the UPS to the AC power supply.
  2. Measure and record the input and output voltage using a multimeter.
  3. Observe the waveform of the output on the CRO.

Step 2: Load Test with Resistive Load

  1. Connect a resistive load (lamp or heater) to the output of the UPS.
  2. Measure the output voltage for different load conditions (light, medium, full load).
  3. Observe and record the output waveform on the CRO.

Step 3: Backup Time Measurement

  1. Disconnect the AC mains supply and note the time when the UPS switches to battery mode.
  2. Measure the time until the UPS shuts down.
  3. Record the backup time for each load condition.

Step 4: Efficiency Calculation

  1. Measure the input power and output power using a multimeter.
  2. Calculate the efficiency using the formula: Efficiency(%)=(Output PowerInput Power)×100\text{Efficiency} (\%) = \left( \frac{\text{Output Power}}{\text{Input Power}} \right) \times 100

Step 5: Switching Time Test

  1. Disconnect the AC power suddenly and measure the time taken by the UPS to switch to battery mode.

5. Observations:

Load Condition Input Voltage (V) Output Voltage (V) Backup Time (s) Waveform Type Efficiency (%)
No Load
Light Load
Full Load

6. Results:

  • The UPS successfully maintained voltage stability under varying load conditions.
  • The waveform type was observed to be (pure/modified) sine wave.
  • Backup time decreased with increasing load.
  • The efficiency ranged between X% and Y%.

7. Conclusion:

The given UPS demonstrated effective performance, providing stable voltage output and efficient backup under different load conditions. Performance metrics such as backup time and efficiency were within expected ranges, making it suitable for uninterrupted power supply needs.