92 GC250 Technical Manual
EAAM057608EN
P.0229
Started engine threshold due
to frequency
20.0 %
10
P.0305
Minimum frequency threshold
90.0 %
45
P.0307
Maximum frequency
threshold
110.0 %
55
P.0202
Hysteresis
2.5 %
1.25
To the two settable thresholds (P.0305 and P.0307) the hysteresis is entirely applied in the
threshold input direction. This means that the frequency is out of tolerance if out of thresholds
P.0305 and P.0307. It is in tolerance if within the thresholds P.0305+hysteresis and P.0305-
hysteresis, otherwise it maintains the previous status.
0
Hz
.
Band A:
absent
5
Hz
.
Band B:
Hysteresis
10
Hz
.
Band C:
minimum
45
Hz
.
D band:
Hysteresis
46.25
Hz
.
Band E:
in tolerance
53.75
Hz
.
Band F:
Hysteresis
55
Hz
.
Band G: m
aximum
xxx
Hz
.
If the frequency is in “B”, “D”, “F” bands, it maintains the status it had before (hysteresis). For
example, if the frequency was in “E” band, and now is in “D” band, it is still considered in
tolerance. On the other hand, if it was in “C” band and now is in “D” band, it is considered
“Low”.
Thresholds P.0305 and P.0307 are used also to manage the generator/engine protections on
frequency. These protections can be individually disabled setting to zero the relevant
parameter that specifies the delay (respectively P.0306 and P.0308). Even if the protections
are disabled, thresholds are however used in order to define the frequency status: this allows
not to switch the loads on the generator if the electrical magnitudes are out of the tolerance
band.
9.3.2
Genset voltages
Several parameters are related to voltage measures of the generator:
P.0101: indicates if it is a three-phase generator (3) or a single-phase generator (1).
P.0102: rated generator voltage. Its value must be the nominal phase-to-phase
voltage for three-phase systems and phase
–to–neutral voltage for single-phase
systems. Thresholds are expressed as a percentage of it.
P.0202: hysteresis applied to all the thresholds related to generator voltage. It is a
percentage value of P.0102.
P.0226: threshold (percentage of P.0102) under which the engine is considered
stopped.
P.0227: threshold (percentage of P.0102) over which the engine is considered started.
P.0301: low generator voltage threshold (percentage of P.0102); under this value the
generator cannot be connected to the loads.
P.0303: high generator voltage threshold (percentage of P.0102); over this value the
generator cannot be connected to the loads.
Let us see a practical example upon how thresholds work, with default values for the
parameters we have seen.
