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Setting Notes
2.8.3
General
The voltage protection can only operate if it has been set to Enabled during the configuration of the device
scope (address 137).
The overvoltage and undervoltage elements can detect phase-to-ground voltages, phase-to-phase voltages or
the symmetrical positive sequence system of the voltages; the symmetrical negative sequence system or the
zero sequence voltage can also be used for overvoltage. Any combination is possible. Detection procedures
that are not required are switched OFF.
NOTE
i
i
For overvoltage protection it is particularly important to observe the setting notes: Never set an over-
voltage element (V
into a state of permanent pickup which cannot be reset by any measured value operation. As a result, oper-
ation of the device would be impossible!
Overvoltage Phase-to-Ground
The phase voltage elements can be switched ON or OFF in address 3701 59-Vph-g Mode. In addition to this,
you can set Alarm Only, i.e. these elements operate and send alarms but do not generate any trip
command. The setting V>Alarm V>>Trip creates in addition also a trip command only for the 59-2 element
(V>>).
The settings of the voltage threshold and the timer values depend on the type of application. To detect steady-
state overvoltages on long lines carrying no load, set the 59-1-Vph PICKUP element (address 3702) to at
least 5 % above the maximum stationary phase-to-ground voltage expected during operation. Additionally, a
high dropout to pickup ratio is required (address 3709 59-Vph RESET = 0.98 = presetting). This parameter
can only be set in DIGSI at Display Additional Settings. The time delay 59-1-Vph DELAY (address 3703)
should be a few seconds so that overvoltages with short duration do not cause tripping.
The 52-2 phase (V
adequately high pickup value is set, e.g. the 1/
then sufficient for the time delay 59-2-Vph DELAY (address 3705).
Overvoltage Phase-to-Phase
Basically, the same considerations apply as for the phase undervoltage elements. These elements may be used
instead of the phase voltage elements or be used additionally.. Accordingly set address 3711 59-Vph-ph
Mode to ON, OFF, Alarm Only or V>Alarm V>>Trip.
As phase-to-phase voltages are monitored, the phase–to–phase values are used for the settings 59-1-Vpp
PICKUP (address 3712) and 59-2-Vpp PICKUP (address 3714).
For the time delays 59-1-Vpp DELAY (address 3713) and 59-2-Vpp DELAY (address 3715) the same
considerations apply as above. The same is true for the dropout ratios (address 3719 59-Vpp RESET). The
latter setting can only be altered in DIGSI at Display Additional Settings.
Overvoltage Positive Sequence System V
The positive sequence voltage elements can be used instead of or in addition to previously mentioned over-
voltage elements. Accordingly set address 3731 59-V1 Mode to ON, OFF, Alarm Only or V>Alarm
V>>Trip.
For symmetrical voltages an increase of the positive sequence system corresponds to a logical AND combina-
tion of the phase voltages. These elements are particularly suited to the detection of steady-state overvoltages
on long, weak-loaded transmission lines (Ferranti effect). Here too, the 59-1-V1 PICKUP element (address
3732) with a longer time delay 59-1-V1 DELAY (address 3733) is used for the detection of steady-state
overvoltages (some seconds), the 59-2-V1 PICKUP element (address 3734) with the short time delay
59-2-V1 DELAY (address 3735) is used for the detection of high overvoltages that may jeopardize insula-
tion.
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
, V
, V
) lower than an undervoltage element. This would put the device immediately
L-N
L-L
1
>>) element (address 3704) is provided for high overvoltages with short duration. Here an
ph
1
2.8 Undervoltage and Overvoltage Protection (optional) 27/59
-fold of the nominal phase-to-ground voltage. 0.1 s to 0.2 s are
2
Functions
115
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