GE KVGC 202, Техническое руководство

Страница: 41 / 150

Technical Manual KVCG202/EN M/H11
KVGC202
4.4.3.3 Intertap Delay
If additional tap changes are required to bring the voltage back within the deadband limits
a definite intertap delay determines the delay between subsequent tap change initiations.
The inter-tap delay will start after the tap pulse duration has elapsed.
While the regulated voltage remains outside the deadband the output relay will continue
to give pulsed closure for the tap pulse duration at intervals determined by the Intertap
Delay. Reduction of the intertap time to 0 seconds will result in a continuous output
indicated by a continuously illuminated red ‘Control’ LED.
4.4.3.4 Tap Pulse Duration (tPULSE)
The tap change initiating signal to ‘Raise Volts’ or ‘Lower Volts’ uses the same tap pulse
duration to increment or decrement the tap position by one. The tap pulse duration is
user selectable, 0.5-5s.
4.4.4 Operating Sequences
For a large voltage deviation outside the set deadband the tap changer is required to
perform a multiple tap change sequence. Two main methods of controlling such a
sequence are as follows:
4.4.4.1 Method 1
This is the standard method and is suitable where rapid correction of large voltage
deviations is required to give better regulation.
The initial delay setting (tINIT) determines the delay in initiating any tap change
sequence. After the set initiating pulse (tPULSE) the inter-tap delay setting determines
the delay between subsequent tap change initiations. This process continues until the
system voltage is restored to within the deadband limits.
For rapid restoration of nominal voltage conditions the inter tap delay can be set equal to
the operating time of the tap changer mechanism, the limitation being that the tap
changer should be able to respond to an output from the VRR.
Although this method of operation provides better system voltage regulation, it may also
result in excessive operation of the tap changer mechanism. An alternative method of
operation is described below which can significantly increase the total time to restore
nominal voltage whilst correcting larger voltage deviations more rapidly.
Figure 6: Initial and inter tap delay used for multiple tap change sequence
4.4.4.2 Method 2
For this method a normally open contact operated by the tap changer mechanism is
connected to an opto assigned to BLOCK. This contact is closed whilst the mechanism is
operating to block the relay. This resets the initial delay timer (tINIT) during each tap
change step and hence the initial timer (tINIT) operates after completion of each tap
change.