User Manual

Description
2.3 Protection system
3WA Air Circuit Breakers
Equipment Manual, 05/2021, 92310000002-03
63
2.3.5.11 Enhanced protective functions EPF
Enhanced protective functions can be added to the function scope of the ETU600 electronic
trip unit. On the basis of the measured currents, voltages and frequency, overshooting or
undershooting of the resulting metering values can cause tripping of the circuit breaker.
The following enhanced protective functions can be used:
• Phase unbalance current (device number 46)
• Phase unbalance voltage (device number 47)
• Total harmonic distortion for current (device number THDC) and voltage (device
number 81THDV)
• Undervoltage (device number 27), overvoltage (device number 59)
• Forward power (ANSI 32F), reverse power (ANSI 32R)
• Underfrequency (device number 81U), overfrequency (device number 81O)
• Reverse-phase sequence protection (device number 46)
Note
Two different calculation methods are used for the calculation of phase unbalance.
• ANSI definition:
Ratio of the greatest difference of the phases from the arithmetic mean value of the
phases.
• IEC definition:
Ratio of the greatest difference of the phase from the phase with the highest load.
The method to be used can be parameterized on the electronic trip unit.
One of the enhanced protective functions trips the circuit breaker when the corresponding
measured value exceeds or falls below the set delay time.
The required voltage tap module is a component of the ETU600 electronic trip unit from
metering function type PMF-I on. The enhanced protective functions are part of the standard
scope of a circuit breaker with metering function from type PMF-II. For more information, see
Chapter Metering function (power metering function) (Page 103).
No external auxiliary voltage is required for the enhanced protective functions.