The paper gives comparative characteristic of a continuously adjustable and stepwise adjustable (switchable) filter-compensating installations (FCI) in the traction network of AC railways. Technical and economic calculations were carried out to increase throughput and reduce electric power losses. Effectiveness of switchable FCI is substantiated, taking into account features of traction.

Feasibility of using regulated FCIs at the traction network at the partitioning station is mainly determined by the need to increase the railway capacity by increasing the voltage on electric locomotive current collector, as well as due to the reduction of electric power losses in the traction network and in the external power supply system.

Efficiency of increasing the carrying capacity of the voltage in the traction network is determined by the maximum power of the FCI, and if these powers in the continuously adjustable, stepwise adjustable and unregulated units are equal, then the effect in increasing the carrying capacity will be the same. The effectiveness of reducing power losses in the traction network when using FCI installation at a partition station is generally limited, firstly, by the fact that electric locomotive is distributed throughout the entire inter-substation zone and, secondly, electric locomotive current is distributed between the partitioning post and the traction substations, and therefore FCI can compensate for only part of the electric locomotive current. This explains the limited possibilities in reducing power losses in the traction network of continuously adjustable FCI.

As a rule, in most cases, according to the operating experience of domestic traction power supply, the nominal power of FCI at the partitioning station is 3–5 Mvar. In the future, as the traction load increases, its capacity will increase to 7–10 Mvar. With an increase in the power of FCI over 10 Mvar, one should consider a distributed system of FCI in the inter-substation zone.