초록 ▼

A DC arc suppression circuit is disclosed for suppressing arcs which occur across a mechanical switch or circuit breaker. Several embodiments are described which employ a bipolar transistor to actively shunt the load current around the mechanical switch when the contacts are opened for a period of t

A DC arc suppression circuit is disclosed for suppressing arcs which occur across a mechanical switch or circuit breaker. Several embodiments are described which employ a bipolar transistor to actively shunt the load current around the mechanical switch when the contacts are opened for a period of time long enough to enable the contacts to be separated by a sufficient distance to prevent arcing. Arcing is prevented when contact bounce occurs upon closure of the contacts, by providing a diode connected in parallel with the base-emitter portion of the circuit which restores the arc suppressing capacity of the circuit almost immediately upon the first closure of the contacts.

대표청구항 ▼

An active arc suppression circuit connected in parallel with a first and second contacts of a relay switch to be protected while switching DC currents, said switch having a characteristic delay for opening said contacts and having said first contact connected to the positive terminal of a DC power s

An active arc suppression circuit connected in parallel with a first and second contacts of a relay switch to be protected while switching DC currents, said switch having a characteristic delay for opening said contacts and having said first contact connected to the positive terminal of a DC power supply and said second contact connected to a load, comprising: an NPN bipolar transistor having its collector connected to said first contact and its emitter connected to said second contact, and a base; a capacitor connected between said collector and said base of said transistor having a capacitance sufficiently large to require an interval longer than said characteristic delay to charge up, for passing load current from said first contact to said base when said contacts are opened, turning on said transistor to shunt said load current around said contacts until said capacitor charges up after said characteristic delay, at which time said transistor turns off; a diode having its cathode connected to said base and its anode connected to said emitter of said transistor, for quickly discharging said capacitor when said contacts are closed; whereby arcs which may occur across said contacts upon opening are suppressed.