Installation advice for automatic reactive power compensation(APFC)
Dec 18,2019

Single busbar compensation


An installation with a single LV busbar is that most often encountered. This type of installation requires that the reactive power can change with respect to the methods defined previously.

Compensation uses all the receiving devices of the installation and the amperage of the current transformer is determined according to the total current conducted through the main protection circuit breaker.

Precautions during installation

As mentioned previously, it will be necessary to ensure a complementary installation of the current transformer so that it can read the total consumption of the installation.

It is indispensable to set up the current transformer (CT) in accordance with Fig. 1,and installing the system at any of the points indicated by a cross would result in the system malfunctioning.

Compensation with several busbars

Independent LV busbars

Another installation possibility is to have the various independent busbars which do not require to be connected to two identical transformers. For this reason:the reactive power requirement will be different for each busbar and need to be evaluated separately using the methods defined previously. Compensation will use all the receiving devices and the amperage of each current transformer will be determined according to the total current through the main protection circuit breaker of each busbar.

Installation precautions

In a similar manner to the previous case, the location of each current transformer(CT) will need to be decided upon in the same way so that some transformers can read the consumption in each part of the installation separately.Refer to Fig.2

Compensation for a busbar supplied by various transformers

An installation differing from the above is one in which there are many transformers connected in parallel on the low voltage side.

Separate distribution transformers

Compensation in this installation can be obtained by placing together the two automatic batteries and their respective current transformers.

Equal distribution transformers

In this case, it will be possible to obtain compensation with a single bank in which the controller is powered by a summing transformer, itself powered by the two CTs of each transformer.

The maximum number of summing inputs is 5 (Fig. 3).

Installation precautions

Separate distribution transformers:

Each bank is powered by a separate CT connected to the output of each transformer.The settings and the installation must be made as if these were independentbusbars.

Equal distribution transformers:

Compensation uses a single bank and the only precaution is to be made on start up:the C/K relation that needs to be programmed into the controller must consider the sum of all the CTs feeding the summing circuit.

installation advice of automatic reactive power compensation
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