Applications and Features:
The XU1-E of the PROFESSIONAL LINE is a digital relay for earth fault detection in isolated and resistively earthed medium voltage systems. Digital filters ensure a suppression of harmonics.
The relay can be connected to the open e-n winding of the voltage transformer.
When compared to conventional protection equipment all relays of the PROFESSIONAL LINE reflect the superiority of digital protection techniques with the following features:
· High measuring accuracy by digital data processing
· Fault indication via LEDs
· Extremely wide operating ranges of the supply voltage by universal wide range power supply
· Very fine graded wide setting ranges
· Data exchange with process management system by serial interface adapter XRS1 which can be retrofitted
· RMS - measurement
· Extremely short response time
· Adjustment of rated data
· Compact design by SMD-technology
· Adjustable trip delay
Unit XU1-E has a single step earth fault voltage supervision. The noise signals caused by inductive and capacitive coupling are supressed by an analog RC- filter circuit.
The analog voltage signals are fed to the A/D- converter of the microprocessor and transformed to digital signals. The analog signals are sampled with a sampling frequency of 16 x fn, namely, a sampling rate of 1.25 ms (1,04 ms) for every measuring quantity at 50 Hz (60 Hz).
The earth fault voltage is compared with the set reference value. Pickup of the supervision circuit is indicated by flashing of the LED UE>, after tripping it is steady lit.