Under / Over Frequency Relay || Power System Lab || EE

Summary

This experiment demonstrates the process of detecting over and under frequencies using a frequency relay system. The setup involves a three-phase supply, power meter, step-down transformer, and an over/under frequency relay. The procedure includes configuring relay settings for both over and under frequency detection, performing self-checks, and measuring the time taken for the relay to trip under specific frequency conditions. By following this procedure, users learn how the frequency relay responds to frequency deviations and how to set parameters for both over and under frequency detection.

Takeaways

• 😀 The experiment involves testing over and under frequency detection in a three-phase system.
• 😀 The three-phase system setup includes a direct online starter panel, power meter, step-down transformer, and frequency relay.
• 😀 The multi-function power meter (EMT 34) measures key parameters like current, voltage, power, power factor, and energy.
• 😀 The step-down transformer converts the supply voltage from 415V AC to 110V AC.
• 😀 The over frequency experiment focuses on setting up the relay to detect frequencies above a specific threshold.
• 😀 In the over frequency experiment, relay settings include values for frequency, time delay, and drop-off frequency.
• 😀 For the over frequency test, the time it takes for the relay to trip is recorded (3.6 seconds in this case).
• 😀 The under frequency experiment follows a similar process, but it focuses on detecting frequencies below a threshold.
• 😀 Both experiments require configuring the relay through menu settings and adjusting values for frequency, time, and drop-off frequency.
• 😀 After configuring the relays, a bypass switch is engaged, and the system performs a self-check before the relay trips.
• 😀 The time taken for the relay to trip in response to frequency deviations is a key measurement in both experiments.

Q & A

What is the primary focus of the experiments described in the script?

The primary focus of the experiments is to study the working of under-frequency and over-frequency detection systems.

What equipment is used to measure the three-phase current, voltage, power, and power factor?

A three-phase multi-function power and energy meter panel, referred to as EMT 34, is used to measure the three-phase current, voltage, power, power factor, and energy.

What is the voltage specification of the three-phase Step Down Transformer?

The three-phase Step Down Transformer has a primary voltage of 415V AC and a secondary voltage of 110V AC.

What is the purpose of the over and under frequency relay in the experiments?

The over and under frequency relay is used to monitor and detect frequency deviations. It is set up for both over-frequency and under-frequency detection in the experiments.

How is the relay setting configured for over-frequency detection?

For over-frequency detection, the relay setting involves configuring the frequency to 49.8Hz, with a drop-off frequency of 1.5Hz, a time of 5 seconds, and a value of 1.01 for channel 1 and 48Hz for channel 2.

What must be done after the relay settings are configured?

After configuring the relay settings, the relay should be reset and the bypass switch must be turned to the right-hand side, followed by pushing the push button and the EMT1 start button simultaneously.

How is the time taken for the relay to trip measured in the over-frequency experiment?

The time taken for the relay to trip is measured by the time it takes for the frequency relay to detect the frequency deviation and initiate a trip, with the result showing a time of 3.6 seconds in the example.

What is the relay setting process for under-frequency detection?

For under-frequency detection, the relay settings involve configuring a frequency value of 52Hz for channel 1, 49.8Hz for channel 2, and a drop-off frequency of 0.1Hz for both channels, with a time setting of 5 seconds.

What does the relay display indicate after the self-check process?

After the self-check process, the relay display shows the configured settings and indicates whether the relay trips based on the frequency values set for the experiment.

What happens when the frequency drops below the channel one value during the under-frequency experiment?

When the frequency drops below the channel one value, the relay trips, and the time taken for the relay to detect the under-frequency condition is measured.