The capacitor bank was to be power capacitor based with automatic control by power factor regulator. This type of device was chosen as a compensator, because of its price compared i.e. to active filters.
Since the detuning factor for the project was given as p=7%, one knows that the capacitor bank needs to be equipped with reactors. For this reason, some calculations have to be performed, in order to fit the power of the capacitors and its rated voltage taking into account reactive power of a detuning reactors.
Considering power capacitor with rated power of 20 kvar and rated voltage of 440V supplied by mains at Un=400V. This type of calculation is true, if there is no reactor connected in series with capacitor. Once we know the total reactive power of the capacitors, we can choose series of capacitors for PF correction.
The first capacitor in the series will have a power of 20kvar. If the remaining power will be managed in a smart way, it will be possible to reduce the cost of the power factor regulator choosing the one, that has 6 outputs instead of 12. Each capacitor by the company is described by the specific name such as CSADG or CSADP.
If the capacitor bank is to be placed in the same place as the main switchgear or utility room next to it, IP 20 is enough. Section construction – in a device for reactive power compensation particular sections can be determined, placing them in separate partitions or within the same cubicle. 1. Enclosure
Q – rated power of the capacitor at rated mains voltage. Not only capacitors should be protected against short circuit, but the whole capacitor bank as well. Usually, in the switchgear from which the CB is supplied, there is an additional circuit breaker for the capacitor bank. Its value should be selected as: