What is phase loss protection?

Phase Loss Protection is a critical motor protection mechanism designed to monitor the phase sequence in the power supply and protect the motor from damage. The following is a detailed introduction to phase loss protection.

Background Of Phase Loss Protection

Phase sequence refers to the sequence of three-phase voltage waveforms in the power supply. Under normal operating conditions, the phase sequence of a three-phase power supply should provide power in a specific sequence (usually ABC or 123).

However, under certain circumstances, such as a power system failure or during maintenance operations, the phase sequence of the power supply may change. In this case, if the motor continues to run, it may cause damage to the motor or cause safety risks.

PR240 Phase Loss Protection Relay

Extention type for Phase failure, Phase unbalance, phase loss protection

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The Principle Of Phase Loss Protection

Phase loss protection is designed to detect the phase sequence in the power supply and take action to stop the operation of the motor if a phase sequence error is detected. Its working principle is usually based on the following steps:

Sensor or detection device: Phase loss protection systems typically use phase sequence
sensors or detection devices to monitor the phase sequence in the power supply. These devices are installed in the motor control system to monitor the voltage waveform of the three-phase power supply in real-time.
Phase sequence comparison: The phase sequence sensor compares the detected voltage waveform with the standard phase sequence. If it is detected that the voltage waveform does not match the standard phase sequence, the system will determine that there is a phase sequence error.
Trigger protection action: Once the system detects a phase sequence error, it will trigger a protection action. Protective action may include cutting off the power supply to the motor, usually by closing the main contactor or circuit breaker. This will prevent the motor from operating in the wrong phase sequence, thereby preventing damage or hazardous conditions.

Applications Of Phase Loss Protection

Phase loss protection is widely used in industrial fields that require highly reliable motor operation, especially those applications that require high motor performance and safety. Here are some common application areas:

Pump Stations and Fan Systems: In water and ventilation systems, the proper operation of motor-driven pumps and fans is critical to keeping the infrastructure operational. Phase sequence loss protection ensures that these systems operate with the correct phase sequence.
Manufacturing:
In manufacturing, many machines and equipment use electric motors. Phase sequence loss protection can prevent motors in the production line from being damaged due to phase sequence errors, ensuring production continuity.
Elevators
and lifting equipment: Elevators and lifting equipment usually use electric motors as the driving force source, so they require reliable phase sequence loss protection to ensure safe operation.
Air conditioning and refrigeration systems: Electric motors in air conditioning and refrigeration systems require a stable power phase sequence to ensure efficient operation.

Phase Loss Protection with PR260 Motor Protection relay

Our PR260 Phase loss protection relay can be a good choice for you if you need a phase loss protection device to protect your motor or other equipment. This phase loss protection relay can monitor the phase sequence of the voltage waveform and take action to prevent failure when a problem is detected. They can quickly detect loss of phase sequence and cut off power or take other necessary measures to protect equipment and power systems. The Phase loss protection of the PR260 Phase loss protection relay: Any two phase current > 25% Rated current, AND the other phase current < 12.5% Rated current, the phase failure protection will be activated.

Parameters:

Protect action	OFF / Alarm / Trip DO
Action delay	0.1 ~ 50.0 s

Note:

This protection will be valid in both the starting and running periods.

Conclusion

In summary, phase loss protection is an important part of motor protection. It can detect and prevent the motor from operating in the wrong phase sequence, thereby protecting the motor from damage and reducing potential safety risks. This is crucial in various industrial applications to ensure the reliability and safety of production processes.