Siemens SIPROTEC 4 Manual page 192

Functions
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
part of Figure "Directional characteristic for cos-ϕ-measurement" in the functional description of the sensitive
ground fault detection).
Information on the Configuration of the Current Threshold
With devices with sensitive ground fault input, generally settings may be entered in primary values with
consideration given to the ratio of the applicable current transformer. However, problems related to the reso-
lution of the pickup currents can occur when very small settings and small nominal primary currents are
involved. The user is therefore encouraged to enter settings for the sensitive ground fault detection in secon-
dary values.
EPTR, TNP - General Information
The function EPTR is switched on or off at address 3501 EPTR.
The function TNP is switched on or off at address 3502 Trans. Neutral.
You can switch between the functions using the connection-type setting CT Connect., address 251). If A,
B, C, (Gnd) is set, EPTR works. If A,G2,C,G; G->B or A,G2,C,G; G2->B is set, TNP works.
EPTR, TNP - Logarithmic-Inverse Knee-Point Characteristic Curve (AMZ)
The logarithmic-inverse characteristic curve for EPTR is set at the following addresses:
3503 Pickup current
3505 EPTR I Tmax, pickup current with maximum delay
3507 EPTR I Tmin, pickup current with minimum delay
3509 EPTR I Tknee, current at the knee-point
3511 T knee, tripping time for the knee-point, the transition of the 2 characteristic-curve sections with
different slope.
3512 T min, minimum delay when the current threshold EPTR I Tmin picks up.
3513 T max, picks up EPTR I Tmax picks up
T min and T max determine the range of the tripping time.
The logarithmic-inverse characteristic curve for TNP is set at the following addresses:
3504 Pickup current
3506 TNP I Tmax, pickup current with maximum delay
3508 TNP I Tmin, pickup current with minimum delay
3510 TNP I Tknee, Strom an Kniepunkt
3511 T knee, tripping time for the knee-point, the transition of the 2 characteristic-curve sections with
different slope.
3512 T min, minimum delay when the current threshold TNP I Tmin picks up.
3513 T max, maximum delay when the current threshold TNP I Tmax picks up.
T min and T max determine the range of the tripping time.
With address 3514 T Function you set the time delay for the complete function.
192 SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017