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voltage which is coupled in at full network displacement. The setting value is finally de-
termined during commissioning with primary values.
The stator earth fault trip is delayed by the time set under address 5005 T S/E/F.
Delay
For the delay time, the overload capacity of the load equipment must be considered.
All set times are additional delay times and do not include operating times (measure-
ment time, reset time) of the protection function itself.
Addresses 5003 and 5004 are only of importance for machines in busbar connection,
Earth Current
where 150 S/E/F PROT. = directional or non-dir. U0&I0 has been set. The
following considerations are not applicable for unit connection.
The pick-up value 5003 3I0> is set so that for an earth fault in the protected zone,
the earth current safely exceeds the setting.
Since the residual earth current in a resonant-earthed network is very small, also to be
independent of network conditions in general, an earthing transformer with an ohmic
loading resistor is normally provided to increase the residual wattmetric current in the
event of an earth fault. Instructions for dimensioning the earth current transformer and
loading resistor are contained in the publication "Planning Machine Protection Sys-
tems", Order No. E86010-K4500- A111-A1.
Since the magnitude of earth fault current in this case is determined mainly by the
loading resistor, a small angle is set for 5004 DIR. ANGLE, e.g. 15°. If the network
capacitances in an isolated network are also to be considered, then a larger angle (ap-
prox. 45°) can be set which corresponds to the superimposition of the capacitance
network current onto the load current.
The directional angle 5004 DIR. ANGLE indicates the phase displacement between
the neutral displacement voltage and the perpendicular to the directional characteris-
tic, i.e. it is equal to the inclination of the directional characteristic to the reactive axis.
If, in an isolated network, the capacitances to earth of the network are sufficiently large
for earth current creation, it is also possible to operate without an earthing transformer.
In this case an angle of approximately 90° is set (corresponding to sin ϕ connection).
Example busbar connection:
With full neutral displacement voltage, the load resistor supplies
7UM61 Manual
C53000-G1176-C127-3
2.21 90-%-Stator Earth Fault Protection (ANSI 59N, 64G, 67G)
Loading resistance
Voltage divider
Toroidal c.t.
Protected zone
10 Ω
10 A
continuous
50 A
for 20s
500 V / 100 V
60 A / 1 A
90 %
133
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