The present disclosure relates generally to switching devices, and particularly to switching devices employing resistance wires.
The electrical current required to charge a capacitor is related to the capacitor's state of charge. In response to the capacitor having a fully discharged state, the charge current flowing into the capacitor will be at a maximum. As the state of capacitor charge increases, the charging current decreases, until the capacitor reaches a fully charged state, at which point the charging current will be zero. A fully discharged capacitor provides no restriction to the flow of charging current. Accordingly, switches (also herein referred to as contactors) for use with capacitors may include a parallel connected auxiliary switch that incorporates resistor wires to control the current flow within desired limits. These types of contactors are referred to as capacitor switching contactors.
Such switch arrangements are configured to incorporate a delay to close an auxiliary circuit (defined by the auxiliary switch and including the resistor wires) prior to closing a main circuit (absent the resistor wires). Therefore, the current to provide an initial charge to the capacitor is maintained at or below a desired limit by the resistor wires. Subsequently, in response to closing the main circuit, the charging current is controlled by the charge state of the capacitor.
Connection of the resistor wires between a set of main terminals and a set of auxiliary terminals may be accomplished utilizing a housing assembly. Such housings may incorporate individually insulated chambers, each chamber having a connecting terminal in connection with one of the resistance wires, and additional components configured to connect with the main terminals. Such housings may restrict airflow surrounding the resistance wire and obstruct access to the main terminals. Alternatively, a cylindrical resistor wire, absent the housing and additional components, maybe utilized in direct, mechanical contact adjoining a set of phase conductors within a connection space provided by each of the main terminals. Direct contact of the cylindrical resistance wire and phase conductor may not provide the strongest mechanical connection. Accordingly, there is a need in the art for a resistor wire arrangement that overcomes these drawbacks.
USPTO Backgrounds
USPTO Backgrounds