Vision Selectronics Ltd

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Tech-E Solutions Capacitors compensation equipment helps customers improve performance through energy savings and better power quality. With our products and solutions customers save money and reduce the environmental impact of their operations.

Low voltage capacitor units are manufactured by using the latest methods. Capacitor elements of metallized polypropylene film are self-healing and dry without impregnation liquid. Each capacitor element is individually protected with patented internal protection. Capacitors have low losses and are constructed to be light in weight.

There is an increasing number of electrical equipment with non-linear voltage-current characteristics connected to the network. Harmonic currents produced by them cause harmonic voltages in network impedances, which add to the fundamental system voltage resulting in voltage distortion. This voltage distortion is experienced by all electrical equipment connected to the network leading to higher thermal loading of motors, transformers, capacitors, switchgear and cabling. Some of the electrical equipment develop more audible noise when supplied with distorted voltage. Sensitive electronic protection, control and ripple control systems are likely not to operate properly when supplied with distorted voltage.

The most effective way to eliminate harmonics is by using an active filter. Tech-E Solutions active filter is based on  Direct Phase Current Control (DPCC) technology. It provides your network with efficient and fast harmonics reduction and reactive power compensation.

Tech-E Solutions Capacitor DW-series automatic capacitor banks with blocking reactors are intended for power factor correction in systems where harmonic distortion is present.



New modular and compact design provide space saving and flexible mounting options for wall or floor mounting. DW-series is available in two variants, standard and extension. Extension types includes space for fast and easy power extension. Reactive power compensation is controlled with high performance reactive power controller N-6.

Automatic capacitor banks are used for central power factor correction at main and group distribution boards. Power factor correction means that reactive power charges levied by electricity suppliers can be avoided. Automatic capacitor banks consist of stages controlled by a power factor controller which ensures that the required capacitor power is always connected to the system. In wall-mounted automatic capacitor banks all components (capacitor units, contactors and fuses) are built into a compact steel enclosure. This makes installation easy and capacitor banks can also be easily expanded if necessary. Expansion is allowed for in the cabling recommendations.



When power ratings in excess of 100 kvar are required cubicle type automatic capacitor banks are used. When selecting compensation for a system which contains a harmonic generating load, check the automatic capacitor bank is suitable for the purpose. In systems where harmonics are present, compensation must be by means of an automatic capacitor bank with blocking reactors (de-tuned filter) or a harmonic filter (tuned filter).

Harmonic filters consist of capacitors connected in series with a reactor. Capacitors produce reactive power at the filter's fundamental frequency ant the circuit is designed to achieve the required power factor correction. The inductance of the reactor is chosen so that the filter forms a very low impedance series resonant circuit at the harmonic frequency. This ensures that a high proportion of the harmonics enter the filter. A typical harmonic filter consist of three series resonant circuits tuned to the most common harmonics (5th, 7th and 11th harmonics). The filters are housed in steel cubicles. Each consists of a contactor, thermal over current relay, reactor and capacitors. The unit is generally connected to the fused feeders on the main distribution board.

Nonlinear one-phase loads such as fluorescent illuminators and computers which are connected between phase and neutral are generating third harmonic and multiple of it. All harmonic currents cause both current and voltage distortion. In addition to this third harmonic currents accumulate in the neutral wire increasing the risk of overloading and caused magnetic field having frequency of 150 Hz. By filtering third harmonic from the network the above mentioned problems can be eliminated.

3rd harmonic filter consists of capacitor units which are connected in series with reactors. The harmonic filter produces reactive power at fundamental frequency in order to reach the target power factor. The inductance of the reactor has been chosen to create very low impedance series resonance circuit for 3rd harmonic. As a result of this most of 3rd harmonic current can be filtered. The filter cubicle has a contactor, a thermal overload relay, reactors, capacitors and a voltage control relay.

Thyristor switched capacitor banks equipped with a fast control are designed to support the line voltage and to compensate the reactive power of the load. Thyristor switches make possible that a fast response is achieved without any mechanical wear, noise or excessive transient associated with contactor switching. A control signal can be brought from the compensated equipment and so it is achieved reactive power compensation almost without delay. All steps of the capacitor bank are switched on during one network period. Each step of the bank consists of a capacitor unit with a blocking reactor. These form a series resonant circuit tuned to a frequency below that of the lowest harmonic.



Capacitor bank is chosen to be suitable for load according to the control system, compensation power and load switching. The compensated equipment can be symmetrical or unsymmetrical for main or phase voltage switched loads.
 

Fixed detuned filters are used to compensate the reactive power in individual, standard-power devices or groups of devices in networks affected by harmonics.

A fixed detuned filter consists of a reactor connected in series with the power capacitor unit. With this construction a resonance phenomenon between network inductance and capacitor capacitance is avoided.

A fixed detuned filter is usually connected in parallel with the device or the group of devices to be compensated. In this way, the capacitor is switched on and off simultaneously with the load. When necessary, a contactor can be installed inside the box in a case when the detuned filter is wanted to be controlled separately.