Siemens Siprotec 7UM611 User Manual

2.17 Frequency Protection (ANSI 81)
111
7UM61 Manual
C53000-G1176-C127-3
specifications. In this context, frequency decrease protection ensures the power sta-
tion’s own demand by disconnecting it from the power system on time. The turbo reg-
ulator then regulates the machine set to nominal speed so that the station's own re-
quirements can be continuously provided at rated frequency.
Under the assumption that apparent power is reduced to the same degree, turbine-
driven generators can, as a rule, be continuously operated down to 95 % of nominal
frequency. However, for inductive consumers, the frequency reduction not only means
greater current consumption but also endangers stable operation. For this reason,
only a short-time frequency reduction down to about 48 Hz (for f
N
= 50 Hz) or 58 Hz
(for f
N
= 60 Hz) is permissible.
A frequency increase can, for example, occur due to a load shedding or malfunction
of the speed regulation (e.g. in an island network). In this way, the frequency increase
protection can, for example, be used as overspeed protection.
Setting example:
Time Delays The time delays T f1 to T f4 entered at addresses 4204, 4207, 4210 and 4213)
allow the frequency stages to be graded. The set times are additional time delays not
including the operating times (measuring time, drop-out time) of the protective func-
tion.
Minimum Voltage Address 4215 Umin is used to set the minimum voltage which if undershot, frequency
protection is blocked. A value of approx. 65 % U
N
is recommended. The parameter
value is based on phase-to-phase voltages. The minimum voltage threshold can be
deactivated by setting this address to 0.
2.17.3 Settings
Stage Cause Settings
for f
N
= 50 Hz for f
N
= 60 Hz Delay
f1 Disconnection
from the network
48.00 Hz 58.00 Hz 1.00 sec
f2 Shutdown 47.00 Hz 57.00 Hz 6.00 sec
f3 Warning 49.50 Hz 59.50 Hz 20.00 sec
f4 Alarm or tripping 52.00 Hz 62.00 Hz 10.00 sec
Addr. Parameter Setting Options Default Setting Comments
4201 O/U FREQUENCY OFF
ON
Block relay
OFF Over / Under Frequency Protec-
tion
4202 f1 PICKUP 40.00 .. 65.00 Hz 48.00 Hz f1 Pickup
4203 f1 PICKUP 40.00 .. 65.00 Hz 58.00 Hz f1 Pickup
4204 T f1 0.00 .. 600.00 sec 1.00 sec T f1 Time Delay
4205 f2 PICKUP 40.00 .. 65.00 Hz 47.00 Hz f2 Pickup
4206 f2 PICKUP 40.00 .. 65.00 Hz 57.00 Hz f2 Pickup
4207 T f2 0.00 .. 100.00 sec 6.00 sec T f2 Time Delay
4208 f3 PICKUP 40.00 .. 65.00 Hz 49.50 Hz f3 Pickup
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Siemens Siprotec 7UM611 Specifications

General

Brand	Siemens
Model	Siprotec 7UM611
Category	Relays
Language	English