25
251/02 en
6
Parallel operation
6.2.2
Function tests, commissioning and
preliminary settings
The voltage regulators must be set to identical operating
parameters for the desired voltage, bandwidth, time delay 1,
and line compensation, if applicable.
The tap position indication at the regulators must function
correctly.
Select the "MANUAL“ operating mode at the voltage
regulators.
Individually set all on-load tap-changers involved in parallel
operation to identical voltage so that the voltage regulators
are in a balanced state
(no presignal appearing on the dis-
play).
Now switch the transformers to parallel operation connect
terminals 90/91. The voltage regulators must continue to
remain in a balanced state and the LED lamps "Parallel“ at
the regulators must respond. Switch the Follower voltage
regulator to the "AUTO“ operating mode.
Use the manual control to raise the MASTER regulating unit
engaged in the "MANUAL“ operating mode by one step; the
follower regulator now has to automatically drag along the
associated transformer to do the same.
During the short period while a tap position difference is
present, the message "TAP DIFFERENCE“ will appear in the
status line of the display. If a follower regulator fails to drag
along its associated transformer, regulating action will be
blocked and a signalling relay will respond (terminals 83/84/
85).
NOTE
T
he prerequisite for the proper functioning of parallel
operation is the commissioning of the voltage regulators
for individual operation.
6.3
Parallel operation with existing parallel control
unit SKB 30 based on "minimum circulating
reactive current"
The following menu item is used for the selection:
The menu item can be selected by pressing the SELECT key
and the
keys and then using the SET and
keys to select parallel operation with supplementary device
SKB 30.
To expand existing plants, the TAPCON® 230 VC voltage
regulator is equipped with a communication interface to an
existing SKB 30 parallel control unit.
The connection of the regulator with the parallel control
unit and the setting for parallel control are made as
described in operating instructions BA 117 (parallel control
unit SKB 30).
Terminals 90, 91, 92, 93, 94, and 95 on the TAPCON® 230 VC
have no function. The parallel operation signal, LED
and
signal relay (terminals 80, 81, 82) remain functional, how-
ever.
6.4
Disturbances during parallel operation
In parallel operation the following messages appear in the
status line (only for twin parallel operation, not for chap.
6.3).
If any of the above disturbances occur, the regulators will be
blocked.
PARALLEL OPERATION
TWIN PARALLEL
SKB/TWIN PARALLEL
25/30
Message
Cause
CIRCULATING
Circulat. reactive current
REACTIVE CURRENT
was exceeded
TAP DIFFERENCE
Synchronism disturbance
(tap difference
£
2 steps)
>1 MASTER
More than one Master
was selected
NO MASTER
No Master was selected
NO POSITION
Failure of position
indication
DIFF. METHOD
Different methods of
parallel operation were
selected