Operation
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6.4 DUMMY LOAD / LOAD SHEDDING CONTROL
This feature may be enabled by the system designer to ensure the loading on the generator is kept to
a nominal amount. If the load is low, ‘dummy loads’ (typically static load banks) can be introduced to
ensure the engine is not too lightly loaded. Conversely as the load increases towards the maximum
rating of the set, non-essential loads can be shed to prevent overload of the generator.
6.2.1 DUMMY LOAD CONTROL
The
dummy load control
feature (if enabled) allows for a maximum of five dummy load steps.
When the set is first started, all configured
Dummy Load Control
outputs are de-energised.
Once the generator is placed onto load, the generator loading is monitored by the
Dummy Load
Control
scheme.
If the generator loading falls below the
Dummy Load Control Trip
setting (kW), the
Dummy Load
Control Trip Delay
is displayed on the module display. If the generator loading remains at this low
level for the duration of the timer, the first
Dummy Load Control
output is energised. This is used to
energise external circuits to switch in (for instance) a static load bank.
The generator loading has now been increased by the first dummy load. Again the generator loading
is monitored. This continues until all configured
Dummy Load Control
outputs are energised.
Should the generator loading rise above the
Dummy Load Return
level, the
Dummy Load Return
Delay
begins. If the loading remains at these levels after the completion of the timer, the ‘highest’
active
Dummy Load Control
output is de-energised. This continues until all
Dummy Load Control
outputs have been de-energised.
6.2.2 LOAD SHEDDING CONTROL
The
Load Shedding Control
feature (if enabled) allows for a maximum of five load shedding steps.
When the generator is about to take load, the configured number of
Load Shedding Control Outputs
at Startup
will energise. This configurable setting allows (for instance) certain loads to be removed
from the generator prior to the set’s load switch being closed. This can be used to ensure the initial
loading of the set is kept to a minimum, below the
Load Acceptance
specification of the generating
set.
The generator is then placed on load. The
Load Shedding Control
scheme begins.
When the load reaches the
Load Shedding Trip
level the
Trip Delay
timer will start. If the generator
loading is still high when the timer expires, the first
Load shedding Control
output will energise. When
the load has been above the trip level for the duration of the timer the ‘next’
Load shedding Control
output will energise and so on until all
Load Shedding Control outputs are energised.
If at any time the load falls back below the
Load Shedding Return
level, the
Return Time
will start. If
the load remains below the return level when the timer has expired the ‘highest’
Load Shedding
Control
output that has been energised will be de-energised. This process will continue until all
outputs have been de-energised.
When the set enters a stopping sequence for any reason the
Load Shedding control
’ outputs will de-
energise at the same time as the generator load switch is signalled to open.
NOTE:- Refer to DSE7400 Series Configuration Suite Manual (DSE part 057-160) for further
details on configuration.
