Applications
An analogue output with a power value may be wired to a switchboard instrument, to help with troubleshooting. For example, use
Section
|
PMS P avail. [kW]
to troubleshoot load-dependent start and stop.
7.3 Genset priority
7.3.1 Genset start and stop priority order
Each genset has a priority that the power management system (PMS) can use to determine which genset to start (or stop) when a
genset start (or stop) is needed. The operator can determine the genset priority. Alternatively, the PMS can determine the genset
priority.
The priorities are used to create a genset priority order, as shown in the following example. The gensets with priority 1 and 2 are
running, while the gensets with priority 3 and 4 are stopped. All the GENSET controllers are in AUTO mode.
G
G
G
G
Priority 1
Priority 2
Priority 3
Priority 4
Genset start
Genset stop
If a genset start is needed, the first non-running genset in the priority order is started. Note that the GENSET controller must also be
in AUTO mode, and the genset must be
Ready for operation
.
In this example, the genset with priority 3 is started. If the genset fails to start, or if the PMS needs another genset to start, the next
genset in the order (the genset with priority 4) is started.
Similarly, if a genset stop is needed, the last running genset in the priority order is stopped. In this example, the genset with priority 2
is stopped.
INFO
Poorly selected genset priorities can lead to inefficient operation in a system that consists of gensets of different sizes. This
is because the PMS ensures that the gensets run according to their priority order, even if it is not the most efficient
configuration.
Genset priority example
The system consists of genset A (1000 kW), genset B (500 kW) and genset C (200 kW). The system requires 800 kW.
•
If genset A has priority 1, then only genset A will run to supply the load.
•
However, if genset C has priority 1, and genset B priority 2, then all three gensets have to run. This is because the
PMS ensures that the gensets run according to their priority order to provide the power required by the load.
Priority in the system
The PMS has one genset priority order, which includes all the GENSET controllers in the system. The genset priority order does not
change when tie breakers open to create new sections. The order does not change when tie breakers close to join sections.
Priority in sections
Within a section, the PMS uses the genset priority order for the GENSET controllers that are in the section.
If a tie breaker opens and splits the section, then the genset priority order for each section consists of only the GENSET controllers
in each section.
DESIGNER'S HANDBOOK 4189340911K UK
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