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975-0593-01-01 31
Circuit Level Advanced Settings
Priority
The Priority setting here is the same as the priority setting discussed in
“Circuit Priority” on page 17. The only difference here is that the change in
priority setting happens from the circuit-level screen in Advanced
Settings instead of from the Config screen.
Generator Soft Start
The purpose of having a generator soft start (GEN Soft Start) feature is
to allow generators to be loaded gradually after the transfer switch flips
from shore power to generator or when the generator is started. Without
engaging the GEN Soft Start feature, all the load circuits controlled by
Freedom Sequence will abruptly get connected to generator power. This
may cause the generator to experience a step load which may cause its
voltage/ frequency to dip and in turn cause nuisance tripping of sensitive
loads.
Each relay of Freedom Sequence that is associated to Line1 or Line2 can be
individually configured to two GEN Soft Start settings: Enabled or
Disabled.
By default, all relays associated to Line1 or Line2 are set to Disabled.
When Freedom Sequence receives the Generator Run (B+) signal high, it
will trigger the AC relays to disconnect load circuits that have GEN Soft
Start configured to Enabled. For AC relays configured to Disabled,
those AC relays will remain connected during the GEN Soft Start
process. After the Generator Run (B+) signal goes high, Freedom Sequence
will apply the Gen Warmup Delay. At the end of this Gen Warmup Delay,
the Freedom Sequence power manager assumes the transfer switch has
toggled and the power manager starts to reconnect the AC relays that have
been set to Enabled. Freedom Sequence will sequentially start to reconnect
all the load circuits in the priority order defined for AC relays.
EXCEPTION: If an AC load Circuit3 is set to a lower priority than an AC
load Circuit2 with a Generator Soft Start setting of Enabled,
Circuit3 will get disconnected to avoid a priority inversion
1
.
1.A priority inversion occurs when an AC load that has a higher circuit priority gets disconnected
first before another AC load that has a lower circuit priority.
AC LOAD
Circuit1
Circuit2
Circuit3
GEN SOFT START
Disabled
Enabled
Disabled
STATUS
ON
ON
ON
PRIORITY
[1]
[2]
[3]
GENERATOR IS OFF
AC LOAD
Circuit1
Circuit2
Circuit3
GEN SOFT START
Disabled
Enabled
Disabled
STATUS
ON
OFF
OFF
PRIORITY
[1]
[2]
[3]
DURING GEN WARM UP DELAY
AC LOAD
Circuit1
Circuit2
Circuit3
GEN SOFT START
Disabled
Enabled
Disabled
STATUS
ON
ON
ON
PRIORITY
[1]
[2]
[3]
GENERATOR IS ON
S
H
O
R
E
G
E
N
S
H
O
R
E
G
E
N
S
H
O
R
E
G
E
N
Circuit3 will get
disconnected to
avoid tripping due to
priority inversion.
Circuit2 will get
reconnected first
then Circuit3
follows, once the
generator power has
been fully ramped up
and stabilized.
FSequence IPM Owners Guide.book Page 31 Thursday, October 6, 2011 3:33 PM