User's manual
PFC max 6, PFC max 12 Page 6
1.3.1 Four quadrant regulators
This term is used to describe the regulators which are able to perform measure and control, either if the
active power flows from the utility to the customer network (the common case of a consuming facility) or if
it flows in the reverse sense. The later is the case of facilities containing power generation equipment
which export some amount of generated power to the utility.
1.3.2 FCP program (FAST PFCized Program)
The units having FCP program, control the switching of capacitor stages in order to minimize the number
of switching operations to reach the required PF compensation. Moreover, the program assigns the
capacitor stages to be connected or disconnected using a FIFO criterion (FIFO= First IN, first OUT), that
way the times of use of all stages are equalized.
1.3.3 Stages and steps
We must distinguish between these two terms. In this manual we call STAGE to each of the capacitor
groups that constitute the PF correction unit. The capacitor stages in PF correction equipment may have
all the same power or not, as explained in the following paragraphs.
The term STEP is used to describe the minimum fraction of reactive power in which the PF correction
equipment is divided. Usually this is the power of the lower stage.
1.3.4 Stages ratio program
Powers of successive capacitor stages in PF correction equipment generally follow certain patterns called
stages ratio program or simply “Program”. The stages program indicates the relationship between the
different capacitor stage powers. Most common stages ratio programs are the as follows:
Program 1:1:1. All capacitor stages have the same rated power (kvar). For instance, a 5-stage unit of
100 kvar would be formed by 5 equal stages of 20 kvar and would be described as a unit of (5 x 20) kvar.
Program 1:2:2. All capacitor stages from the second and up have a rated power (kvar) which is twice the
rated power of first stage. For instance, a 5-stage unit of 180 kvar would be formed by a first stage of 20
kvar and 4 equal stages of 40 kvar, and would be described as a unit of (20 + 4 x 40) kvar.
Program 1:2:4. The rated power of the second stage is twice the rated power of the first stage and the
rated power of third stage and up is 4 times the power of the first stage. For instance, a 5-stage unit of
300 kvar would be formed by a first stage of 20 kvar, a second stage of 40 kvar and 3 equal stages of 80
kvar, and would be described as a unit of (20 + 40 + 3 x 80) kvar.
Other switching programs. Other switching programs are also commonly available, like 1:2:2:4 or
1:1:2:2, etc. Abbreviated designation form, as can be deduced from previous cases, consists of a
sequence of numbers giving the relationship between the different stage powers (kvar), and the first
stage power, which value is taken as unit (1 ). The successive stages will be designated by 1, or 2 or 4,
etc. meaning that the kvar ratio of such stages with regard to first stage are equal, twice, four times, etc.
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