
3
Directional or Non-Directional 
Earth-Fault Relay
Technical Reference Manual
REJ 527
1MRS 750616-MUM
Issued: 07.07.99
Version: B/05.07.2002 
Checked: A.S.
Approved: L.N.
We reserve the right to change data without prior notice.
Contents
1. Introduction ...............................................................................5
1.1. About this manual .........................................................................5
1.2. The use of the relay ......................................................................5
1.3. Features ........................................................................................5
1.4. Guarantee .....................................................................................6
2. Safety information .....................................................................7
3. Instructions ................................................................................8
3.1. Application .....................................................................................8
3.2. Requirements ................................................................................8
3.3. Configuration .................................................................................8
4. Technical description .............................................................10
4.1. Functional description .................................................................10
4.1.1. Product functions .............................................................10
4.1.1.1. Schema of product functions ..............................10
4.1.1.2. Earth-fault current, zero-sequence voltage and 
intermittent earth-faults ......................................10
4.1.1.3. Inputs .................................................................11
4.1.1.4. Outputs ...............................................................11
4.1.1.5. Circuit-breaker failure protection unit .................11
4.1.1.6. Disturbance recorder ..........................................11
4.1.1.7. HMI module ........................................................11
4.1.1.8. Non-volatile memory ..........................................11
4.1.1.9. Self-supervision ..................................................12
4.1.2. Measurements .................................................................12
4.1.3. Configuration ....................................................................13
4.1.4. Protection .........................................................................13
4.1.4.1. Block diagram ....................................................13
4.1.4.2. Directional or non-directional earth-fault 
current unit 14
4.1.4.3. Zero-sequence voltage unit ................................18
4.1.4.4. Protection against intermittent earth-faults .........19
4.1.4.5. Time/current characteristics ...............................20
4.1.4.6. Settings ..............................................................29
4.1.4.7. Technical data on protection functions ..............37
4.1.5. Indicator LEDs and alarm indication messages ...............38
4.1.6. Commissioning test ..........................................................39
4.1.7. Disturbance recorder .......................................................39