Soft Transfer - Datakom D-500 MK2 User Manual

D-500 MK2 User Manual

29.3. SOFT TRANSFER

In this mode, the transfer will be made without interruption like the Uninterrupted Transfer mode. But the
load will be gradually transferred under active and reactive power control.
The Soft Transfer sequence starts like an Uninterrupted transfer. But when both contactors are activated,
the unit starts transferring the kW and kVAr load to the mains with a predefined ramp (Active Power
Ramp, Reactive Power Ramp). The duration of the load transfer sequence is controlled by the Soft
Transfer Timer.
The unit offers a comprehensive set of protection functions to detect quickly a mains failure during parallel
operation with mains. The protections are enabled after the timeout defined by the parameter Parallel
Check Delay. 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 de-
energize, a general Parallel Mains Fail warning and a specific protection function warning will be
generated.
At the end of the Soft Transfer Timer, the load contactor will be released. If any alarm is encountered
during the Soft Transfer sequence, the controller will revert to the Interrupted transfer.
The controller has a set of programmable parameters to define the Soft Transfer operation. All
parameters used in Uninterrupted Transfer are also used in Soft Transfer. Additional parameters are:
Parameter Definition Description
Soft Transfer Enable
Soft Transfer Timer
Active Power Ramp
Reactive Power
Ramp
Ramp On High Limit
Ramp Off Low Limit
Parallel Check Delay
This parameter enables/disables the Soft Transfer feature.
This is the time duration of the Soft Transfer. At the end of this timer one of
the contactors will release to terminate the parallel operation
The load's active power (kW) will be transferred to the mains with this rate.
The load's reactive power (kVAr) will be transferred to the mains with this rate.
This parameter defines high limit of soft transferring from busbar to mains.
This parameter defines low limit of soft transferring from busbar to mains.
This is the delay after the mains contactor is energized (for parallel to mains)
and before the protections for mains failure are enabled.
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Firmware V-6.3