Duplex reactors are three-phase current-limiting reactors with central tapping which can be a beneficiary option to the power system operation when connected certain configuration between two utility-fed distribution system buses and local generator source.
Reactors > Special Application Reactors
Duplex Reactors
Duplex reactors are generally installed at a juncture where a large source of power is split into two simultaneously, and equally, loaded buses. Duplex reactors can be applied to systems which always remain isolated.
The design feature of the Duplex reactors is to offer a low-rated reactance under normal operating conditions and high-rated reactance under fault conditions.
The operating principle of a duplex reactor is as follows:
- It consists of two magnetically-coupled coils per phase. This magnetic coupling dependent on the geometric proximity of the two coils determines the properties of a duplex reactor under steady-state and short circuit operating conditions.
A) Steady-state condition:
During steady-state operation, magnetic fields produced by two windings are in opposition, and therefore, the effective reactance between power source and each bus is at minimum.
B) Short-circuit condition:
In a short-circuit situation, the linking magnetic flux between the two coils becomes unbalanced, resulting in higher impedance on the faulted bus; thus restricting fault current.
- Voltage on unfaulted bus is supported significantly by the effects mentioned below, until the fault is cleared:
A) The effect of reactor impedance between faulted and unfaulted bus, and,
B) The “voltage boosting” effect caused by the coupling offaulted leg with unfaulted leg of duplex reactors.
