Transient Earth Fault Relay Type EWR 22 - a. eberle - #1

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1 A. Eberle GmbH & Co. KG Technical Data a-eberle Transient Earth Fault Relay type: EWR 22 T854D201- issue 11/2003 Features · adjustable trigger value of the zero sequence voltage and the measured current · suppression of the transient earth fault signals depending on the selected minimum time of the zero sequence voltage · suppression of earth fault signals towards the bus bar (optional) · in case of a new earth fault the choice for retention or reset of the previous status and indication of actual direction of the earth fault is possible · signal status remains in case of power supply failure (bistable relay) · manual reset of the indication by an external signal or automatically after a selectable time · signal for zero sequence voltage UNE>U as LED and relay output available as * plug-in card 12 U * case for panel surface mounting * case for panel flush mounting * case for DIN-rail mounting 35mm Application Transient earth fault relays monitor each feeder of the bus bar and signal transient earth faults and transient earth faults with continuous earth faults. The different features of the relay and the easy change of parameters offer an optimal adaptation to the system. Description The chosen acquisition principle follows the proven technique of the transient earth fault relay EWR 2 and EWR 20/21. For the detection of an earth fault and its „direction“ the zero sequence voltage UNE and the zero-sequence-current are measured and their polarities are compared immediately after an earth fault event. To prevent an accidental reaction of the transient earth fault relay this comparison is only carried out in a very small time slot. The zero sequence voltage is used as a reference quantity for the direction of the zero-sequence-current. If both measured quantities have the same polarity the earth fault lies in the direction of the feeder, in case of an unbalanced polarity towards the bus bar. figure 1 function diagram of the EWR 22 1 measuring circuit zero-sequence-current 2 measuring circuit zero sequence voltage (3x 100/110 or open delta winding) 3 comparison and evaluation of signals 4 signal for continuous earth fault 5 signal for earth fault towards bus bar 6 signal for earth fault towards feeder 7 signal for operation 8 signal for malfunction 9 signal UNE higher than the limit >U 10 reset input (external) 11 power supply 12 test 13 reset key Signals The following indications can be configured with the DIPswitch S3 Retriggering of the indication of the transient earth fault With each new transient earth fault linked with a changed direction of the zero-sequence current the indication also changes when no reset was carried out manually or by signal. Between the transient earth faults the zero-sequence voltage must fall under the limit of >U No retriggering of the indication of the transient earth fault After the first transient earth fault the signal remains stored until it has been acknowledged. The following transient earth faults will not be signalled. (k) (l) U1N U2N U3N N 1 2 3 4 5 6 + - + - UH 7 Test 10 12 Reset 13 8 UNE 2 N 9 s1 s2 11 IE