InteliMains
NT
, SW version 3.2.0
InteliMains-NT-MCB-MGCB-3.2.0-Reference Guide.pdf,
©ComAp – April 2015
114
del
)
– i.e. logical binary output S
YS
START
/
STOP
activates. This output should be wired (or shared via
CAN) to gen-set controllers logical binary input S
YS
START
/
STOP
.
In some cases it may be crucial to choose when the MCB opens after Mains failure (i.e. when there is
protection of Mains protect or Mains protect with Reset
type active). It is possible to choose whether the breaker
opens directly when Mains failure is detected or when
there is healthy bus voltage detected (MGCB only) or
when there is at least one gen-set running. This is done
via setpoint
AMF setting:
MCB opens on.
When the Mains parameters become OK again it is possible to adjust the delay time
which must elapse before InteliMains starts the return to Mains procedure. This delay
is adjusted by
AMF setting:
Mains ret del.
This function is particularly useful when the
Mains fail happens several times in a row with short period of Mains being OK.
It is also possible to choose option that return to Mains needs manual confirmation
before InteliMains starts the return procedure. You can choose this by setpoint
AMF setting:
RetFromIsland
. For the full description of manual confirmation of return
procedure refer to the decription of the setpoint.
By default return to Mains (when the Mains parameters are OK again and
AMF setting:
Mains ret del
elapses) is done by reverse synchronization of gen-set group back to Mains, soft unload of gen-sets
and opening of their GCBs or by opening MGCB (in case of MGCB application).
When it is not possible to synchronize to Mains (Parallel operation is
not enabled, Synchronization is not enabled, Synchronization is
unsuccesfull etc.), return with break may be enabled to ensure that
the load returns to Mains even though parallel operation is not
possible.
AMF setting:
ReturnWithIntr
enables the return with break
(the duration of the break is given by the setpoint
AMF setting:
FwRet break
). If return with break is
disabled and it is not (for whatever reason) possible to synchronize back to Mains, the systems stays
running in Island operation even though the Mains is OK.
In some cases there may be no gen-sets running during the Mains fail (e.g. they are
not able to start, not able to start in time, there may be alarms on all the gen-sets,
they are not in AUT mode etc.). In this case AMF function recloses MCB back to
healthy Mains after delay given by
AMF setting:
MCB close del
elapses.
In MGCB application there is also setting for the duration of breaker overlap
available. This time (given by the setpoint
AMF setting:
BreakerOverlap
) defines
maximal time for run in parallel during return to once again healthy Mains (even
though soft unloading is not completed, after
AMF setting:
BreakerOverlap
elapses the MGCB is opened regardless of load on gen-sets).
In the version IM-NT-3.1.0, there has been change in the behaviour of logical binary output Sys
start/stop in AMF function. This behaviour prevents repetitive starting and stopping of gen-sets in case
of fluctuating Mains parameters. The following diagram shows what the behaviour is now.
The change influences the situation when the Mains parameters are not OK, AMF start sequence is
initiated but before gen-sets are capable to support the load Mains goes OK again. Previously the
gen-sets were stopped immediately and the
AMF setting:
MCB close delay
was counted down. Now
the gen-sets are kept in start sequence until the MCB is really closed. This prevents prolongued
periods of time when the no power was delivered to the load if Mains parameters kept fluctuating,
preventing continuous connection to Mains but also succesfull start and run of a gen-set group.
Mains fails
Breaker opens
immediately
Breaker opens
on Bus voltage
Brk opens on
gen-sets run
Mains is OK
again
Delay before
return procedure
(Manual
confirmation)
Return
procedure
Synchro-return
not possible
System stays in
Island operation
System perform
return with break
No gen-sets run
(Mains OK again)
Delay before
MCB reclosing
MCB recloses
Breaker overlap elapses
(soft unld not done)
MGCB opens
