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The SMOR system recloser allows up to 4 attempts to reclose the line breaker.
For each of these attempts it is possible to set independently the time that should elapse before the reclosing
order is issued. In addition, it is possible to set which functions can initiate the recloser, and, after a given
reclosing, which functions can trip the breaker again. This makes it possible to implement certain protection
arrangements which required special wiring and functions in conventional units. For example, if the user
wants the first protection trip to be instantaneous and the second, after the reclosure, to be timed, in order to
allow time for the fuses of a feeder to blow. To do this, you only have to set the unit to allow only timed trips
after the first reclosure.
It may also be desirable for the reclosing function to be carried out only in certain circumstances, for instance
when there is a trip due to a current unbalance (activation of the negative sequence unit), but not when it is
due to an instantaneous unit.
At this point we should mention that the RECLOSE INITIATION comes into operation following a trip that has
been programmed to generate reclosing. The system also allows the possibility of initiating the recloser by
the activation of a digital input. In this way it is possible to co-ordinate reclosing with other protection
operations.
The recloser has a setting called "MAX TRIPS 1h" (maximum number of trips in one hour) (included in the
group of breaker settings), which can be set between 1 and 50 trips per hour. This setting prevents damage
of the breaker in certain cases, such as a storm for example, in which the protection could be tripping and
reconnecting an excessive number of times. To limit the number of operations, the relay creates a time
window of 1 hour in which it registers the number of trips that occur in that period. This window moves
continuously so that it always indicates the number of trips that have occurred in the hour up to the present
moment. If the number of trips exceeds the setting, the recloser stops working (and moves to the lock-out
status shown in figure 5).
From now on we will use the term "lock-out" instead of block to distinguish the situations in which blocking
occurs due to the activation of an input or by setting, by the desire of the user (the only ones in which we use
the term blocking) from any other type of blocking (no reclosing conditions, permanent fault, etc.).
There is another setting called "RESET TIME" which is the time the unit waits after a successful reclosing
before returning to the reset/ready status. This is also the time which the recloser waits before returning to
the reset/ready status following a manual closure. From now on we will refer to this value as the reset time.
The system allows the possibility of programming a series of conditions which must be fulfilled for the
reclosing to occur. These conditions are :
Condition 0:
Reclosing always occurs.
Condition 1:
While the input "Reclose inhibit" is active there is no reclose. Reclose takes place when this
input is deactivated.
Condition 2:
Reclosing occurs when there is voltage only on the busbar side.
Condition 3:
Reclosing occurs when there is voltage on the busbar side, regardless of the presence of
voltage on the line side.
Condition 4:
Reclosing occurs when there is voltage on the line and on the busbar side.
NOTE : The level of voltage both for the line and for the busbar is 80% of rated voltage.
If the "HOLD MODE" is set to "YES", the recloser waits for the time set in the "HOLD TIME" setting for the
reclosing condition selected in the "RECLOSE CONDITIONS" setting to be fulfilled. If this reclosing condition
is not fulfilled in this time, the recloser goes to the "lockout" status.
If the "HOLD MODE" is set to "NO", the recloser does not take into account the time programmed in the
"HOLD TIME" setting. See figure 5.
GEK-105593C
18
2.4.3. RECLOSER
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