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5. Switching strategy
Steps switching is based on the average value of the reactive power consumption of the load
during the switching delay time.
It allows:
• to control the PF in the presence of rapidly varying loads
• to use a longer switching delay time and as a result, to reduce the number of switchings.
On the basis of the reactive power demand measured during the switching delay time, the
RVC identifies the number of steps to be switched on.
It then automatically switches the bigger outputs first to avoid unnecessary intermediary
switchings.
During this switching sequence, a fixed 12-second delay time between each step is
introduced in order to avoid transient problems and to fulfil EMC requirements.
When several steps must be switched off, the controller does it in one shot because capacitor
switch-off is transient-free.
All the switching sequences are circular.
Circular switching increases the lifetime of capacitors and contactors by balancing the
switching stress among all the outputs.
In case of “double first step” (1:1:2:2…; 1:1:2:4:4:…; 1:1:2:4:8:8:..), the circularity applies to
the first two outputs and also on the outputs of higher value.
6. Modes
AUTO Mode
• Steps are automatically switched on and off to reach the target cos
ϕ
according to the
measurement of the reactive current, the C/k setting, the switching delay, the number of
outputs and the type of sequence
• The LCD display shows the actual cos
ϕ
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