Siemens Sentron SB TP01 Series - Undervoltage; Voltage Unbalance

Extended Protective Relaying
37
7.5 Undervoltage
If the amount of voltage on any phase goes below a specified
level, the trip unit can alarm or trip by setting the parameters
from the Undervoltage selection of the Protective Relays
Menu . To alarm, or to trip and alarm, on undervoltage:
1. From the Protective Relays Menu , select Under Voltage.
The Alarm checkbox is highlighted, but alarming has not
yet been set.
2. To enable alarming, press the Up Arrow key, then press
Enter . If you have enabled alarming, a checkmark
appears and the pickup settings are highlighted.
3. Select a pickup value by pressing the Up or Down
Arrow keys until the value is at the desired level. The pos-
sible pickup values depend on the rating of the breaker;
see the table in the appendix, Parameter Settings . Press
Enter .
4. Then select a delay time by pressing the Up or Down
Arrow keys until the value is at the desired level. Possi-
ble time delay settings are 1, 2, 3, 4, 5, 7, 10 and 15 sec-
onds. Press Enter .
7.6 Voltage Unbalance
Voltage unbalance is a protective relay function that protects
against an unbalance in the line to line voltages. Each line-to-
line voltage is compared to the arithmetic average of the three
voltages. Tripping or alarming occurs when any voltage
exceeds the unbalance pickup for a period of time equal to the
delay time setting. To alarm, or to trip and alarm, on current
unbalance:
1. From the Protective Relays Menu , select Voltage Unbal-
ance . The Alarm checkbox is highlighted, but alarming
has not yet been set.
2. To enable alarming, press the Up Arrow key, then press
Enter . If you have enabled alarming, a checkmark
appears and the pickup settings are highlighted.
3. Select a pickup value by pressing the Up or Down
Arrow keys until the value is at the desired level. The pos-
sible pickup values depend on the rating of the breaker;
see the table in the appendix, Parameter Settings . Press
Enter .
4. Then select a delay time by pressing the Up or Down
Arrow keys until the value is at the desired level. Possi-
ble time delay settings are 1, 2, 3, 4, 5, 7, 10 and 15 sec-
onds. Press Enter .
If you want to
enable...
Then...
alarming only follow steps 2–4 and press Escape
. Then press Enter at the verifi-
cation screen.
alarming and tripping follow steps 2–4, press Enter to
highlight the Trip checkbox, then
repeat the process you used in
steps 2–4 to set pickup and delay
values. After setting both the alarm
and trip values, press Escape .
Then press Enter at the verifica-
tion screen.
If you want to
enable...
Then...
alarming only follow steps 2–4 and press Escape
. Then press Enter at the verifi-
cation screen.
alarming and tripping follow steps 2–4, press Enter to
highlight the Trip checkbox, then
repeat the process you used in
steps 2–4 to set pickup and delay
values. After setting both the alarm
and trip values, press Escape .
Then press Enter at the verifica-
tion screen.