Siemens SIPROTEC 4 7VK61 Manual Download

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In the event of a single cycle reclosure this interrogation is usually sufficient. Since, for example, the air pres-
sure or the spring tension for the circuit breaker mechanism drops after the trip, no further interrogation
should take place.
For multiple reclosing attempts it is highly 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 moni-
toring 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 1-pole tripping this applies to each individual circuit 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

, 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 circuit 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 (3-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, in addition, when signals taken from the CB
auxiliary contacts indicate that the CB (pole) has opened.
If, after a 1-pole trip command, the CB has opened 3-pole, this is considered as a 3-pole tripping. If 3-pole
reclose cycles are allowed, the dead time for 3-pole tripping becomes active in the operating mode with trip
command (see margin heading “Operating modes of the automatic reclosure”, above). If 3-pole cycles are not
allowed, the reclosure is blocked dynamically. The trip command is final.
The latter also applies if the CB trips two poles following a 1-pole trip command. The device can only detect
this if the auxiliary contacts of each pole are connected individually. The device immediately initiates 3-pole
coupling which results in a 3-pole trip command.
If the CB auxiliary contacts indicate that at least one further pole has opened during the dead time after 1-pole
tripping, a 3-pole reclose cycle is initiated with the dead time for 3-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 3-pole trip command provided that the forced 3-pole trip
is activated (see Section

2.2.2 Setting Notes

at margin heading “Forced 3-pole trip”).

Sequence of a 3-pole reclose cycle

If the automatic reclosure function is ready, the fault protection trips 3-pole for all faults inside the stage
selected for reclosure. The automatic reclosure function is 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) dead time is started. If, when
configuring the protection functions, at address 134

AR control mode

with Pickup

was set, different

dead times can be parameterised depending on the type of fault recognised by the protection.
If the fault is cleared (successful reclosure), the reclaim time expires and all functions return to their quiescent
state. The fault is cleared.
If the fault has not been eliminated (unsuccessful reclosure), the short-circuit protection initiates a final trip
following a protection stage active without reclosure. Any fault during the reclaim time leads to a final trip.
After unsuccessful reclosure (final tripping) the automatic reclosure function is blocked dynamically (see also
margin heading “Reclose Block”, above).

Siemens SIPROTEC 4 7VK61, Manual

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