Static Power iSTS W - Input Transient Settings

iSTS W
– User Manual
Page 23
Phase
error detection break (ms)
Setting
this value to ‘0’ turns on the intelligent transfer delay mode where the device will automatically
calculate
a
break time based on the degree of difference between the two supplies. For more information refer
to
‘Prevention
of Transformer Saturation’ technical report.
Otherwise
this can be set from 10 – 150 msec with resolution of 10 msec. These are typical break insertion
times;
additional
time would be added as a result of thyristor turn-off delays.
NOTE
: In the scenario that two supplies are significantly out of synchronism, a break time will be insert to
prevent
inadvertent
damage to equipment, tripping of protection devices or opening of fuses.
6
.8 Input Transient Settings
These
figures define the upper and lower limits of deviation from the nominal voltage and current of the
input
power
that creates the fault condition to trigger the alarm and record the event.
S
1 transient high value (%)
Default
value of 115%, can be changed from a nominal value of 105 to 135. This number will be set
as
percentage
. Transient time constant for this parameter is defined by “transient over-sampling time constant 3
x
312
µsec”.
S
1 transient low value (%)
Default
value of 85%, can be changed from a nominal value of 70 to 95. This number will be set as
percentage.
Transient
time constant for this parameter is defined by “transient over-sampling time constant 3 x 312 µsec”.
S
2 transient high value (%)
Default
value of 115%, can be changed from a nominal value of 105 to 135. This number will be set
as
percentage
. Transient time constant for this parameter is defined by “transient over-sampling time constant 3
x
312
µsec”.
S
2 transient low value (%)
Default
value of 85%, can be changed from a nominal value of 70 to 95. This number will be set as
percentage.
Transient
time constant for this parameter is defined by “transient over-sampling time constant 3 x 312 µsec”.
Re
-transfer timeout (sec)
This
parameter defines the delay before a re-transfer back to the original preferred source after the fault
has
been
cleared and the source has returned to normal steady state conditions. The default value for this
parameter
5
seconds. If this is set to a value too small, an unstable condition could arise from the source not having
enough
time
to recover.
Re
-transfer max attempts
This
setting refers to the number of times the device will transfer back to the preferred source. A lock out
results
after
this but is re-set on a new fault alarm condition. The default value is 3. A setting of “0” inhibits retries
and
device
will not transfer back to the preferred source.
NOTE
: Adjustment may be required to the Transient values if the source supply voltages are distorted or above
or
below
nominal. Setting too close a limit to the actual operating Steady State voltage may cause erratic Static
Transfer
Switch
operation.