2 Functions
104
7UM61 Manual
C53000-G1176-C127-3
Figure 2-31
Logic diagram of the undervoltage protection
2.15.2 Setting Notes
General
The undervoltage protection is only effective and available if this function was set
during protective function configuration (Section 2.2, address
140
,
UNDERVOLTAGE
is
set to
Enabled
. If the function is not required
Disabled
is set. Address
4001
UNDERVOLTAGE
serves to switch the function
ON
or
OFF
or to block only the trip
command (
Block relay
).
Settings
It must be note that the positive phase-sequence voltages and thus also the pickup
thresholds are evaluated as phase-to-phase quantities (terminal voltage ·
√
3). The first
undervoltage protection stage is typically set to about 75% of the nominal machine
voltage, i.e. address
4002
U<
is set to 75 V. The user must select a value for the
4003
T U<
time setting that ensures that voltage dips which would affect operating stability
are disconnected. On the other hand, the time delay must be large enough to avoid
disconnections during admissible short-time voltage dips.
For the second stage, a lower pickup threshold
4004
U<<
e.g. = 65 V should be com-
bined with a shorter trip time
4005
T U<<
e.g. = 0.5 s to achieve an approximate ad-
aptation to the stability behaviour of the consumers.
All setting times are additional time delays which do not include the operating times
(measuring time, drop-out time) of the protective function.
The drop-out ratio can be adapted in small steps to the operating conditions at address
4006
DOUT RATIO
.
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Содержание Siprotec 7UM611
Страница 16: ...Contents 16 7UM61 Manual C53000 G1176 C127 3 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 232: ...2 Functions 232 7UM61 Manual C53000 G1176 C127 3 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 292: ...3 Mounting and Commissioning 292 7UM61 Manual C53000 G1176 C127 3 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 410: ...A Appendix 410 7UM61 Manual C53000 G1176 C127 3 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...
Страница 412: ...Literature 412 7UM61 Manual C53000 G1176 C127 3 w w w E l e c t r i c a l P a r t M a n u a l s c o m ...