Static Switching Module CTB2PH

The static switching module CTB2PH includes, in a compact size, all the components necessary to realize the switching of three-phase capacitors. CTB2PH modules use thyristors instead of electromechanical contactors. The static system is the most convenient in case of large and fast fluctuations of the load current (load changes lasting a few milliseconds to several seconds).

The advantages of the static system are the connection at zero crossing voltage and the disconnection at zero current crossing, thus avoiding inrush current transients. CTB2PH modules are composed of two basic parts: control module and power block. As an added accessory, both parts can be mounted with a polycarbonate cover.

Voltage230 V – 400 V
Switching Power12,5 kvar – 80 kvar
Current36 A, 72 A, 115 A
Frequency50/ 60 Hz
Control module power suply12 Vcc
VentilationFan convention
Protection control moduleBy means of thermostat NC. Max. 90º C
Fan protectionThermostat control. Contact NO 70º C
Switched phasesL1,L2 (L3 connected straight through)
Protection degreeIP00
AccessoryPolycarbonate cover. part number (COVERCTB2PH)
Datasheet19/11/20180.2 MB

Traditional reactive power compensation equipment with electromechanical contactors, has a well proven performance in installations where the load has, slow variations and it is not very sensitive to voltage fluctuations. Today, however, more and more industrial installations include electronic equipment very sensitive to voltage variations (PLC, computers, etc.) and also very fast changing working cycles (automatic welding machines, robots, etc.).

Reactive power compensation with static contactors offers the best answer to these new industry requirements.

LIFASA automatic capacitor banks with static contactors, use thyristors instead of traditional contactors. The thyristors switch-on capacitors on zero crossing voltage, and switch them off on zero current  situation. This firing strategy grants a totally transient free switching of power capacitors, avoiding any problem with transient overvoltages.

This transient free switching gives a very fast reaction time of the power factor equipment with sudden reactive power demand variations. This reaction time (the time to switch on or off a capacitor step) is usually not higher than 20 milliseconds. This means that up to 25 operations per second are possible.


LIFASA automatic capacitor banks with static contactors are supplied completely assembled and ready for use: it is only necessary to give them the operation signal from a suitable current transformer, and to connect them to the mains by cables of adequate section. They are composed of the following elements:


These banks use the MASTER FAST controllers, that are a fast response variation of the MASTER series of controllers. These controllers are specially designed for the control of thyristor capacitor banks and are characterized by their optically isolated outputs and also for having an extremely fast response time that can be up to 20 milliseconds.


It is composed by an electronic control circuit, that gives the triggering pulses to thyristors to switch on at zero cross voltage point and to switch off when zero cross current situation.

The control module is assembled on a printed circuit board and receives the action signal from the MASTER FASTER.


It is formed by thyristors, mounted with well-dimensioned heatsinks, protection fuses and limiting inductances.


These banks use FML/ FMLF/ POLB series of LIFASA power capacitors.

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