Siemens Siprotec 7VK61 Manual page 47

Especially when multiple reclosing attempts are programmed, it is recommended to monitor the circuit breaker
condition not only prior to the first, but also before each following reclosing attempt. Reclosure will be blocked
until the binary input indicates that the circuit breaker is ready to complete another CLOSE-TRIP cycle.
The time needed by the circuit breaker to regain the ready state can be monitored by the 7VK61. This monitor-
ing time CB TIME OUT (address 3409) starts as soon as the CB indicates the not ready state. The dead time
may be extended if the ready state is not indicated when it expires. However, if the circuit breaker does not
indicate its ready status for a longer period than the monitoring time, reclosure is dynamically blocked (see also
above under margin heading „Reclosure Blocking").
Processing the circuit breaker auxiliary contacts
If the circuit breaker auxiliary contacts are connected to the device, the reaction of the circuit breaker is also
checked for plausibility.
In the case of single-pole tripping this applies to each individual breaker pole. This assumes that the auxiliary
contacts are connected to the appropriate binary inputs for each pole („>CB1 Pole L1", No. 366; „>CB1
Pole L2", No. 367; „>CB1 Pole L3", No. 368).
If, instead of the individual pole auxiliary contacts, the series connections of the normally open and normally
closed contacts are used, the CB is assumed to have all three poles open when the series connection of the
normally closed contacts is closed (binary input „>CB1 3p Open", No. 411). All three poles are assumed
closed when the series connection of the normally open contacts is closed (binary input „>CB1 3p Closed",
No. 410). If none of these input indications is active, it is assumed that the breaker is open at one pole (even if
this condition also exists theoretically when two poles are open).
The device continuously checks the position of the circuit breaker: As long as the auxiliary contacts indicate
that the CB is not closed (three-pole), the automatic reclosure function cannot be started. This ensures that a
close command can only be issued if the CB has previously tripped (out of the closed state).
The valid dead time begins when the trip command disappears or signals taken from the CB auxiliary contacts
indicate that the CB (pole) has opened and that the trip command has disappeared.
If, after a single-pole trip command, the CB has opened three-pole, this is considered as a three-pole tripping.
If three-pole reclose cycles are allowed, the dead time for three-pole tripping becomes active in the operating
mode with trip command (see margin heading „Operating modes of the automatic reclosure", above); in
control by pickup the pickup diagram of the starting protective function(s) still applies. If three-pole cycles are
not allowed, the reclosure is blocked dynamically. The trip command was final.
The latter also applies if the CB trips two poles following a single-pole trip command. The device can only detect
this if the auxiliary contacts of each pole are connected individually. The device immediately initiates three pole
coupling which results in a three-pole trip command.
If the CB auxiliary contacts indicate that at least one further pole has opened during the dead time after single-
pole tripping, a three-pole reclose cycle is initiated with the dead time for three-pole reclosure provided that this
is permitted. If the auxiliary contacts are connected for each pole individually, the device can detect a two-pole
open CB. In this case the device immediately sends a three-pole trip command provided that the forced three-
pole trip is activated (see Section 2.2.2 at margin heading „Forced three-pole trip").
Sequence of a three-pole reclose cycle
If the automatic reclosure function is ready, the fault protection trips three pole for all faults inside the stage
selected for reclosure. The automatic reclosure function is then started. When the trip command resets or the
circuit-breaker opens (auxiliary contact criterion) an (adjustable) dead time starts. At the end of this dead time
the circuit-breaker receives a close command. At the same time the (adjustable) reclaim time is started. If
during configuration of the protection function address 134 AR control mode was set = with Pickup ...,
different dead times can be set depending on the pickup type of the protective element.
If the fault is cleared (successful reclosure), the reclaim time expires and all functions return to their quiescent
state. The fault is cleared.
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
2.2 Automatic reclosure function (optional)
Functions
47