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Phase failure relay

Phase failure relay for phase monitoring

Phase failure relays are an economical investment that is simple to install.

A three-phase monitor relay protects against damage caused by phase loss as well as other three-phase fault conditions

Thiim A/S can offer phase failure relays for many applications, and multiple supply voltages.

phase-failure

Voltage & asymmetry

The phase failure relays are designed for applications where a three-phase system needs to be monitored for unbalance or deviation in balanced voltage.

The relays includes a standard timing function. In addition the PADI and PANI offers a true time delay on drop out even at total power failure. The relay works in "fail safe" mode and need no external power supply. If an external stable power supply is available the 45mm housing offers separate terminals for internal power.

A - function monitors the three-phase system for unbalance due to phase angle and phase voltage deviations eg. a blown fuse or a bad connection.

B - function monitors the three-phase system for both unbalance (as the A - function) and balanced under voltage.

C - function monitors the three-phase system for both unbalance (as the A - function) and balanced over voltage.

D - function Monitors the three-phase system for all possible deviations by monitoring unbalance and balanced under-and over voltage.

Unbalance due to phase angle and phase voltage deviations is very accurately measured by measuring the inverse phase system relatively to the main system. The method is independent of the actual balanced voltage and very insensitive to electrical noise. Balanced voltage is measured by rectifying and adding the threephase voltages.

Use to:

  • switch off motors automatically before damage due to faulty supply, and to switch them on again as soon as the supply is re-established. Eg. pumps, oilburners, ventilators and refrigerators.
  • monitor the three-phase main system and control the use of local emergency generators.
  • prevent motors from being switched on to a faulty supply e.g. cranes and elevators.

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Voltage, asymmetry & phase rotation

The PAHA & PAHI are 3 wire relays for sequence control and phase monitoring. The PAHI includes a true time delay.

The PAMA & PAMI are 4 wire relays for sequence control and phase and neutral monitoring. The PAMI includes a true time delay.

The phase sequence and phase and neutral monitoring relays are designed for applications where the sequence of a three-phase system needs to be controlled.

In addition to the sequence control the relays monitors the three-phase system for phase unbalance, and according to the selected setting, they can further monitor balanced under or over voltage, as well as both under and over voltage.

The relays work in "fail-safe" mode and the 35mm modules need no external power supply. If an external stable power supply is available, the 45mm modules offer separate terminals for the internal power.

Unbalance, due to phase angle and phase voltage deviation, is very accurately measured by measuring the inverse phase system relatively to the main system. The method is independent of the actual balanced voltage and perfect for the protection of three-phase motors, generators and transformers.

The measuring system is insensitive to higher harmonics and secures the relays from false triggering due to "noisy" power lines. As the measuring system includes the phase angles in the measurement, it provides full protection against regenerated phases. Balanced voltage is measured by adding the three individual rectified phase voltages.

Use to:

  • prevent motors from rotating in the wrong direction and connecting to a faulty supply.
  • motor protection by controlling the direction of rotation and switching on and off depending on the supply conditions. For example, pumps, compressors, fans and refrigerators.
  • automatic control of phase sequence and monitoring of phase and neutral voltages in mobile equipment such as refrigerated containers, control and distribution panels and machines used on construction sites and in service tasks.

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Voltage, asymmetry & frequency

The phase failure relays are designed for applications where a three-phase system needs to be monitored for unbalance or deviation in balanced voltage or deviation in frequency.

PADF includes a standard timing function.
The PADF offers seperate terminals for internal power.

A - function monitors the three-phase system for unbalance due to phase angle and phase voltage deviations e.g. a blown fuse or a bad connection.

B - function monitors the three-phase system for both unbalance (as the A - function) and balanced under voltage.

C - function monitors the three-phase system for both unbalance (as the A - function) and balanced over voltage.

D - function Monitors the three-phase system for all possible deviations by monitoring unbalance and balanced under-and over voltage.

Unbalance due to phase angle and phase voltage deviations is very accurately measured by measuring the inverse phase system relatively to the main system. The method is independent of the actual balanced voltage and very insensitive to electrical noise. Balanced voltage is measured by rectifying and adding the three-phase voltages.

Use to:

  • switch off motors automatically before damage due to faulty supply, and to switch them on again as soon as the supply is re-established. Eg. pumps, oilburners, ventilators and refrigerators.
  • monitor the three-phase main system and control the use of local emergency generators.
  • prevent motors from being switched on to a faulty supply e.g. cranes and elevators.
  • monitor grid frequency and control the use of local generators or standby supplies.
  • protect diesel generator systems from overspeed and underspeed.
  • protect electrical and electronic equipment from damage due to over- and under-frequency.

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