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Functions
2.13 Dir. Intermittent earth fault protection
Pickup
The setting of parameter Pickup defines under which conditions pickup is detected and fault recording started.
For with Vgnd/3V0>, pickup is initiated once the threshold Vgnd> / 3V0> has been exceeded. For with
oper. dir., pickup is initiated when a pulse is detected in the direction specified at address 3402. The pickup
disappears when the displacement voltage has fallen below the threshold Vgnd> / 3V0> and the time
Monitoring time has expired.
Alarm/Trip
The setting of parameter Direction defines whether the function operates in forward or in reverse direction.
The pulses in the specified direction are counted. If the pulse counter reaches the threshold value set in pa-
rameter No. of pulses, the function trips or generates an alarm. It is possible that not every ignition pulse
is recognized as such. If two ignition pulses are very close to one another in respect of time, they may not be
detected separately. This is not relevant from the protection perspective, because during an intermittent fault
many ignition pulses occur and the counter threshold is certainly reached.
The directional pulse counter is reset under the following conditions:
• A different direction than the set Direction is detected. An undefined direction result does not reset the
counter.
• The monitoring time Monitoring time has elapsed. No other pulse in the set direction was detected
during that time. This time can be understood as a criterion for the disappearing of the intermittent fault. The
function thus also drops out if the intermittent fault develops into a static fault.
• V0 is lower than the set threshold Vgnd> / 3V0> and the time Monitoring time has expired.
Interaction with other Functions
The directional intermittent ground fault protection does not interact with the automatic reclosing function. The
function cannot start the automatic reclosing function.
The directional intermittent ground fault protection interacts with the circuit-breaker failure protection. The func-
tion starts the circuit-breaker failure protection.
2.13.2
Setting Notes
General
Configuration of the protection functions at address 134 Dir. Interm. EF defines whether the directional
intermittent ground fault protection is Enabled or Disabled.
At address 3401 Dir. Interm. EF the directional ground fault protection is switched on or off. The following
setting options are available:
ON enables the function with tripping and fault record log.
•
• ON with GF log enables the function with tripping, fault record log and ground fault log.
• Alarm Only generates the ground fault log only. Tripping and fault record log are not possible.
• OFF disables the function.
The pickup threshold for the displacement voltage is set at address 3405 Vgnd> / 3V0>. Exceeding this
threshold is the criterion for detecting the intermittent ground fault.
The direction to be protected Forward or Reverse is set in address 3402 Direction.
Address 3403 No. of pulses allows you to specify how many pulses must be detected in the set direction
before the alarm or tripping is initiated. It is possible that not every ignition pulse is recognized as such. If two
ignition pulses are very close to one another in respect of time, they may not be detected separately. This is
216
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012
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