Description of Controls
Page 71 of 90 057-233 ISSUE: 1
4.12 LOAD SHEDDING CONTROL
This feature may be enabled by the system designer to ensure the loading on S2 is kept to a nominal
amount. Conversely as the load increases towards the maximum rating of the set, non-essential loads
can be shed to prevent overload of S2.
4.12.1 LOAD SHEDDING CONTROL
NOTE: Refer to DSE335 Configuration Suite Manual (DSE part 057-237) for further details
on configuring, monitoring and control.
The Load Shedding Control feature (if enabled) allows for a maximum of five load shedding steps.
When S2 is about to take load, the configured number of Load Shedding Control Outputs at Startup
energises. This configurable setting allows (for instance) certain loads to be removed from S2 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 S2.
S2 is then placed on load. The Load Shedding Control scheme begins.
When the load reaches the Load Shedding Trip level the Trip Delay timer starts. If S2 loading is still
high when the timer expires, the first Load shedding Control output energises. When the load has
been above the trip level for the duration of the timer the ‘next’ Load shedding Control output
energises 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 starts. If the
load remains below the return level when the timer has expired the ‘highest’ Load Shedding Control
output that has been energised is de-energised. This process continues until all outputs have been
de-energised.
When the set enters a stopping sequence for any reason the Load Shedding control’ outputs are de-
energised at the same time as the S2 load switch is signalled to open.
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