Programming Settings for Time-Overcurrent Ground Protection

General The functions associated with time-overcurrent protection were established during configuration of protective functions (Section 5.1) at address . If address 

was set equal to 'HILQLWH7LPHRQO\, then only the settings for the definite-time elements are available.

At address )&711, ground time-overcurrent protection may be switched 21 or 2)) independent of the phase time-overcurrent protection.

Pickup values, time delays, and characteristic curves for ground protection are set separately from the pickup values, time delays and characteristic curves associated

F# LCD-Text Comment

1761 50(N)/51(N) PU 50(N)/51(N) O/C GENERAL PICKUP 1791 50(N)/51(N)TRIP 50(N)/51(N) GENERAL TRIP

F# LCD-Text Comment

1751 50/51 PH OFF 50/51 O/C switched OFF 1752 50/51 PH BLK 50/51 O/C is BLOCKED 1753 50/51 PH ACT 50/51 O/C is ACTIVE 1762 50/51 Ph A PU 50/51 Phase A picked up 1763 50/51 Ph B PU 50/51 Phase B picked up 1764 50/51 Ph C PU 50/51 Phase C picked up 1800 50-2 picked up 50-2 picked up

1805 50-2 TRIP 50-2 TRIP

1810 50-1 picked up 50-1 picked up

1815 50-1 TRIP 50-1 TRIP

1820 51 picked up 51 picked up

1825 51 TRIP 51 TRIP

1866 51 Disk Pickup 51 Disk emulation Pickup

1804 50-2 TimeOut 50-2 Time Out

1814 50-1 TimeOut 50-1 Time Out

1824 51 Time Out 51 Time Out

1851 50-1 BLOCKED 50-1 BLOCKED

1852 50-2 BLOCKED 50-2 BLOCKED

1855 51 BLOCKED 51 BLOCKED

1704 >BLK 50/51 >BLOCK 50/51 1721 >BLOCK 50-2 >BLOCK 50-2 1722 >BLOCK 50-1 >BLOCK 50-1

1723 >BLOCK 51 >BLOCK 51

with phase protection. Because of this, relay coordination for ground faults is indepen-dent of relay coordination for phase faults, and more sensitive settings can often be applied to ground protection.

50N-2 Relay Ele-ment

The pickup and delay of the 50N-2 relay element are set at addresses 1

3,&.83 and 1'(/$< respectively. The same considerations apply for these settings as did for 50-2 settings discussed earlier.

The delay set at address  is in addition to the 50N-2 element’s pickup time. The delay of the 50N-2 element may be set to ∞. The 50N-2 element will then pickup and generate a message, but will never trip. If the 50N-2 element is not required at all, then the pickup value should be set to ∞, thus preventing pickup, trip, and the generation of a message.

50N-1 Relay Ele-ment

The pickup value of the 50N-1 relay element (set at address 13,&.83) should be set below the minimum anticipated ground fault current in the relay’s zone of protection.

If the 7SJ62 relay is used to protect transformers or motors with large inrush currents, the energization stabilization feature may be used to prevent a false trip of the 50N-1 relay element. The configuration data for the energization stabilization feature is pro-grammed at address block 22 (see Subsection 6.5.2).

The delay of the 50N-1 element is set at address 1'(/$< and should be based on system coordination requirements.

The delay set at address  is in addition to the 50N-1 element’s pickup time. The delay of the 50N-1 element may be set to ∞. The 50N-1 element will then pickup and generate a message, but will never trip. If the 50N-1 element is not required at all, then the pickup value should be set to ∞, thus preventing pickup, trip, and the generation of a message.

51N Relay Element with IEC Curves

Pickup of the 51N relay element will occur for currents greater than or equal to 110 % of the 51N pickup value, and may or may not occur for currents between 100 % and 110 % of the 51 element’s pickup value. Dropout of the 51N relay element occurs when the current decreases to 95 % of the 51N element’s pickup value.

The pickup value of the 51N element is set at address 13,&.83. As is the case for the 50N-1 relay element, the pickup value of the 51N relay element should be set below the minimum anticipated ground fault current in the relay’s zone of protec-tion.

The 51N element time multiplication factor is set at address  17,0(',$/

and should be based on system coordination requirements.

The time multiplication factor may also be set to ∞. The 51N element will then pickup and generate a message, but will never trip. If the 51N element is not required at all, address  should be set to 'HILQLWH7LPH2QO\ during protective function con-figuration (see Section 5.1).

51N Relay Element with ANSI Curves

Pickup of the 51N relay element will occur for currents greater than or equal to 110 % of the 51N pickup value, and may or may not occur for currents between 100 % and

The pickup of the 51N element is set at address 13,&.83. As is the case for the 50N-1 relay element, the pickup value of the 51N relay element should be set below the minimum anticipated ground fault current in the relay’s zone of protection.

The corresponding time dial is set at address 17,0(',$/ and should be based on system coordination requirements.

The time dial may be set to ∞. The 51N element will then pickup and generate a mes-sage, but will never trip. If the 51N element is not required at all, address  should be set to 'HILQLWH7LPH2QO\ during protective function configuration (Section 5.1).

Manual Close Mode When a circuit breaker is closed into a faulted line, a high speed trip by the circuit breaker is often desired. The relay’s manual closing feature is designed to remove the delay from one of the time-overcurrent elements when a circuit breaker is manually closed into a fault. The time delay may be bypassed for one of the three time-overcur-rent phase elements and one of the three time-overcurtime-overcur-rent ground elements via an pulse from the external control switch, thus resulting in high speed tripping. This im-puls is prolonged by a period of 300 ms. Address 0$18$/&/26(02'( can be set such that the delay is defeated for the 50N-2 element, the 50N-1 element, the 51N element, or none of the elements (,QDFWLYH). Defeating the delay on just one of the three elements allows control over what level of fault current is required to initiate high speed tripping of a circuit breaker that is closed into a fault.

If the manual closing signal is not from a 7SJ62, that is, neither via the built-in operator interface nor via a series interface, but, rather, directly from a control acknowledgment switch, this signal must be passed to a 7SJ62 binary input, and configured accordingly so that the element selected for high speed tripping will be effective.

Interaction with Au-tomatic Reclosing Equipment

At address 1DFWLYH, it can be specified whether or not the 50N-2 ele-ments should be supervised by the status of an internal or external automatic reclosing device. If address  is set to ZLWKDFWLYH, the 50N-2 elements will not op-erate unless automatic reclosing is enabled. If address  is set to $OZD\V, the 50N-2 elements will always operate.

User-Specified Curves

If address  was set to 8VHU'HILQHG3LFNXS&XUYHor 8VHU'HILQHG

3LFNXSDQG5HVHW&XUYH during configuration of the user-specified curve option, a maximum of 20 value pairs (current and time) may be entered at address 

11 to represent the time-current characteristic curve associated with the 51N element. This option allows point-by-point entry of any desired curve.

If address  was set to 8VHU'HILQHG3LFNXSDQG5HVHW&XUYH during configuration of the user-specified curve option, additional value pairs (current and re-set time) may be entered at address 0RI385HV77(S to represent the reset curve associated with the 51N element.

Current and time values are entered as multiples of the address  and  set-tings. Therefore, it is recommended that addresses  and  be initially set to 1.00 to simplify the calculation of these ratios. Once the curve is entered, the settings at addresses  and  may be modified if necessary.

Upon delivery of the device, all time values are set at ∞, preventing pickup of the de-vice from initiating a trip signal.

When entering user-specified curve data, the same instructions apply as in Subsec-tion 6.2.2.1 for the phase elements.