Phase fault relays
Thiim Relays / Products / Phase fault relays
Advantages of our phase fault relays
- Reliable detection of phase faults and phase imbalance
- Protection against phase loss, incorrect phase rotation, and asymmetry
- Supports multiple supply voltages and network types (TT/TN/IT)
- Suitable for industrial motors, electrical panels, and power supply systems
- Easy installation and quick fault diagnosis
Phase fault relays
Phase fault relays – protect your AC installations against critical phase faults
Phase faults can cause serious damage to motors, transformers, and converters—often without warning. With a reliable phase fault relay from Thiim, you get an effective solution for monitoring AC supplies, ensuring early detection of phase imbalance, phase asymmetry, phase rotation, and phase voltage.
Our relays monitor three-phase installations in both grounded (TT/TN) and ungrounded (IT) systems and warn of deviations in phase frequency, phase deviation, and phase loss. This makes them indispensable in systems with sensitive or expensive components, such as AC motors, converters, and transformers.
Here you can see a selection of our many phase fault relays – contact us to find out more.
Voltage and phase rotation

PNDA-PNDI
Voltage and phase rotation – PNDA-PNDI
The PNDA/PNDI relays detect undervoltage in each phase (3P+N power grid).,
and phase rotation to ensure that star-connected AC motors and drive systems
is correctly supplied and rotates in the desired direction.
Advantages:
- Devices for all common nominal system voltages 100 VAC-480 VAC
- 3 user-selected nominal voltages in the same unit
- Wide range of sensitivity, undervoltage level, and time delay settings
- 6-second self-powered backup in case of total power loss (PNDI version)
Tension and asymmetry

PADA-PADI-PANA
Phase asymmetry and tension – PADA-PADI-PANA
PADA/PADI and PANA/PANI phase fault relays are used to detect phase-to-phase faults.
outages and imbalances due to phase angle or phase voltage deviations.
They can be used to automatically shut down AC motors before damage occurs as a result of power supply faults, and to restart them when the correct supply has been restored.
Advantages:
- Devices for a wide range of nominal system voltages 100 VAC-480 VAC
- Selection of 3 nominal voltages in one unit
- Powered from the installation or separate power supply
- 6-second self-powered true time delay as backup (PADI and PANI versions)
Voltage, asymmetry, and phase rotation

PAHA-PAHI-PAMA
Phase asymmetry, voltage, and phase rotation – PAHA-PAHI-PAMA
PAHA/PAHI and PAMA/PAMI relays detect phase failure and imbalance due to phase angle or phase voltage deviations, as well as phase rotation in 3-phase systems with or without neutral connection.
Advantages:
- Devices available for all common nominal voltages 100 VAC-480 VAC
- 3 nominal voltages selectable in one unit
- Supplied from the installation or from a separate external power supply
- 6-second self-powered true time delay as backup (PAHI and PAMI versions)
- Individual adjustment of unbalanced and balanced under- and overvoltage levels
Voltage and frequency

PAFA-PAGA
PHASE ASYMMETRY, VOLTAGE, AND FREQUENCY – PAFA-PAGA
PAFA and PAGA relays detect phase failure and phase restoration in 3-phase systems with or without neutral connection. They are designed to monitor imbalances caused by phase angle and phase voltage deviations, as well as deviations in nominal frequency.
Advantages:
- Devices available for all common nominal voltages 100 VAC-480 VAC
- 3 nominal voltages selectable in one unit
- Separate power supply that ensures continuous functionality in the event of a total power failure in the monitored system
- Individual adjustment of unbalanced and balanced under- and overvoltage levels
- Further adjustment of under- and overfrequency (% deviation from nominal)

PAFB-PAGB
Phase asymmetry, voltage, frequency, and phase rotation – PAFB-PAGB
PAFB and PAGB are phase fault relays that offer combined monitoring of multiple
electrical parameters in 3-phase systems, with and without neutral connection.
They primarily detect phase failure and imbalance caused by phase angle or phase voltage deviations, as well as phase rotation. In addition, they also detect deviations in nominal frequency.
Advantages:
- Units available for all common nominal voltages 100 VAC-480
- 3 nominal voltages selectable in one unit
- Separate power supply that ensures continuous functionality in the event of a total power failure in the monitored system
- Individual adjustment of unbalanced and balanced under- and overvoltage levels