CIRCUTOR EMK Series - Manual (Page 9)

EMK series
Instructions Manual M98118701-01-12A 9
From the electrical standpoint, the unit is made up of the following blocks:
4.6.1 Fast regulator
Static capacitor banks are equipped with computer Max f, computer Smart f or computer Plus
TF fast regulators. The outputs of these regulators are static; that is to say, instead of an output via
relay contact they have a semiconductor-based switch which allows them to perform operations in
rapid succession, practically every network cycle. This type of output is prepared to drive COM and
ACT inputs on CPCxx zero switching controller
Fast regulators enable regulation with minimum delay, generally between 20 and 100 ms. (see
manual for the specific regulator being used)
4.6.2 CPC, zero switching controller
Static capacitor banks are equipped with CPCxx controllers (xx means that there are different
types according to the network voltage, control voltage and control type).
The role of the CPCxx is to control the switching of the thyristors at zero voltage during the turn
ON operation, thus avoiding current transients. The typical connection diagram of a single step is
shown in Fig. 4-3 and in more detail in the simplified wire diagram in section 10.
CPC controllers are powered with an auxiliary voltage U
aux
. The standard CPCs are mainly used
for networks with Umax = 440 V, nevertheless they have a dual-voltage supply circuit able to be
supplied at a rated voltage of 230V or 400 V (±10%) . There are special controllers, type CPC3i,
which are designed to operate on networks up to 690V. Notice that even for the latter case, the
auxiliary control voltage, U
aux
must be 400 V or 230 V. The CPC3i controllers allow three-phase or
individual phase-phase control, thanks to an RS-485 bus. However, the standard control is through
a voltage-free static contact (semiconductor-based), which opens or closes the circuit between the
controller's COM and ACT terminals.
Fig. 4-3 .- Basic connection diagram of the CPCxx to the power block
4.6.3 Power block:
The power block of an EMK unit is made up of 3 to 12 thyristors + capacitor groups, depending on
the type. Each group consists of a 6-terminal capacitor (three single-phase capacitors), three (*)
thyristor modules attached to a cooling heatsink and the suitable protection elements addapted to
the module's rated power (1 fuse and 1 inductance limiter of di/dt per phase).
(*) On some models the three thyristor modules are integrated into a single encapsulated package