DATAKOM DKG-705 User’s Manual
705_USER.doc
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8. PARALLELING WITH MAINS: PEAK LOPPING
The Peak Lopping feature consists on the use of the genset as a backup to the mains in cases
where the mains power rating is insufficient to supply the load.
The peak lopping application is only possible with slowly varying loads.
When peak lopping is enabled and the unit is in
AUTO
mode, the genset will start and enter in
parallel with the mains if mains power exceeds the parameter
P_A29
(genset start limit). As the mains
power limit is not exceeded it will not supply power to the load.
When the total load power exceeds the parameter
P_A28
(mains power limit) the unit will allow the
mains to deliver only
P_A28
(mains power limit) to the load. The exceeding quantity will be supplied by the
genset.
When the total load power falls below the parameter
P_A30
the generator contactor will release
and the genset will stop following a cooldown cycle.
The parameter
P_A30
should be less than the parameter
P_A29
in order to prevent immediate
stopping of the genset after start.
The unit includes a comprehensive set of protection functions to detect quickly a mains failure
during parallel with mains operation. The protections are enabled after the timeout defined by the
parameter
P_A23
. These protections will be explained with more detail in the following chapter.
If a
mains failure
occurs during parallel with mains operation, the mains contactor will immediately
deenergize, a general
Parallel Mains Fail
warning and a specific protection function warning will be
generated. The load will be supplied by the genset without interruption. When mains is restored again, the
genset will synchronize with the mains and resume to parallel operation.
The DKG-705 has a set of programmable parameters to define the Peak Lopping operation. All
parameters used in No Break Transfer and Soft transfer are also used in Peak Lopping. Additional
parameters are:
P_A27 Peak Lopping Enable:
This parameter enables/disables the Peak Lopping operation.
P_A28 Mains Power Limit:
This is maximum active power that the mains may deliver.
P_A29 Genset Start Limit:
This is the mains active power limit for the start of the genset.
P_A30 Genset Stop Limit:
This is the total load active power for the stop of the genset.
