Multifunctional phase detector - Detects the state of the open phase and the sequence of phases using LED indicators and a buzzer, helping verify correct wiring and safe operation. Frequency range and indicators - Frequency range: 20 Hz to 400 Hz. - Equipped with red, green and yellow LEDs and a buzzer to clearly indicate status during use. Performance and safety - Fast and accurate measurement with stable performance. - Efficient, reliable, and easy to use, providing safe operation during daily tasks. Durable construction - Made of high-quality ABS material; lightweight, resistant to wear and corrosion; long service life. Key benefits - Quickly confirms correct phase sequence and detects open phases to prevent miswiring and equipment damage. - Clear visual and audible signals reduce interpretation errors on site. - Simple operation supports routine electrical maintenance and troubleshooting with minimal training. Applications and use scenarios - Field installation and commissioning of three-phase systems: verify phase sequence and ensure there is no open phase before startup. - Motor troubleshooting: check for incorrect phase order or single-phase faults that could cause improper motor operation. - Daily electrical panel maintenance in workshops or facilities: perform fast checks to confirm correct wiring and safe system status. This device provides a compact, reliable solution for phase identification and open-phase detection, suitable for electricians, maintenance technicians and electrical engineers.