Uninterrupted Transfer - Datakom D-500 MK2 User Manual

D-500 MK2 User Manual

29.2. UNINTERRUPTED TRANSFER

In this mode, the transfer will be made without power interruption from genset to mains. This implies
that both of the mains and generator contactors will be active during transfer.
The maximum duration that both contactors will be active is programmable. However this process may be
quicker with the use of one auxiliary feedback contact from each contactor. Thus the changeover will be
quite instantaneous, preventing any excess or reverse power condition.
To prevent a phase to phase short circuit below criteria must be met:
-The mains and generator voltages must be equal,
-The mains and generator voltages must have the same phase,
-The mains and generator voltages must have the same phase sequence.
The unit will allow an Uninterrupted Transfer only if all of the below conditions are fulfilled:
-Mains phase voltages within the programmed limits,
-Mains frequency within the programmed limits,
-Genset phase voltages within the programmed limits,
-Genset frequency within the programmed limits,
-Mains phase order correct (or phase order check must be disabled),
-Genset phase order correct (or phase order check must be disabled),
-The difference between mains and genset frequencies not more than programmed limit,
-The voltage difference mains-L1 and genset-L1 not more than programmed limit,
-The phase angle between mains-L1 and genset-L1 not more than programmed limit,
When an uninterrupted transfer cycle is started, the unit will wait until the expiration of the
Synchronization Fail Timer, to find a matching frequency, phase and voltage.
Usually, with frequencies matching at +/- 2Hz and voltages matching at +/-10 volts an Uninterrupted
Transfer is expected to successful.
If matching is found before the expiration of the Synchronization Fail Timer, then both contactors will be
activated. If contactor auxiliary contacts are used, the other contactor will release immediately. If
contactor auxiliary contacts are not used, the other contactor will release after contactor timeout .
The unit offers below parameters for the setup of the Uninterrupted transfer feature.
Parameter Definition Description
No Break Transfer
Enable
Synchronization Fail
Timeout
Synchronization
Contactor Timeout
Max Freq Difference
Max Volt Difference
Max Phase Difference
Phase Offset
0: only interrupted transfer enabled
1: no break transfer enabled
If the phase and voltage synchronization is not successful before the
expiration of this timer, then a Synchronization Fail warning is given and the
transfer will be performed with interruption.
When synchronization is detected, both contactors will stay closed during this
timer.
This is the maximum difference between mains and genset frequencies to
close both contactors.
This is the maximum difference between the mains phase-L1 and the genset
phase-L1 voltages to close both contactors. If voltage transformer is used, this
quantity is multiplied with voltage transformer ratio.
This is the maximum phase angle between the mains phase-L1 and the
genset phase-L1 voltages to close both contactors.
This parameter is used to compensate the phase angle introduced by voltage
transformers in case of MV synchronization. This angle value is added to the
phase differential during phase matching process.
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Firmware V-6.3