Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
252 words
A switching circuit for making and breaking an electrical load by means of an electromagnetic relay having electrical contacts for making and breaking said load and a primary coil for actuating said contacts, a bidirectively controlled contactless switch is connected in parallel with said contacts and an optical coupler having a light emitting section and a light sensitive section is connected to control said contactless switch, wherein at making, the bidirectively controlled contactless switch first will connect the load, and after a certain period of time, the electromagnetic relay contacts will be energized to connect the load; and at breaking, the electromagnetic relay contacts will first open, whereupon the bidirectively controlled contactless switch will disconnect the load at a zero voltage phase crossing; the optical coupler includes a zero voltage phase crossing detector, wherein after activation or deactivation of the light-emitting section, the zero voltage phase crossing detector will detect a zero voltage phase crossing of the load energy source so that the light-sensitive section activates or deactivates the bidirectively controlled contactless switch at a zero voltage phase crossing of the load energy source, and the primary coil of the electromagnetic relay is connected in series with a transistor, said transistor amplifies the voltage level from a first RC-network, comprising a first resistor and a first capacitor, said first RC-network is connected in parallel to the transistor and the primary coil, with the base of the transistor connected between the resistor and the capacitor, to delay the energizing of said primary coil.
Claim 2
Dependent Claim
252 words
A switching circuit for making and breaking an electrical load by means of an electromagnetic relay having electrical contacts for making and breaking said load and a primary coil for actuating said contacts, a bidirectively controlled contactless switch is connected in parallel with said contacts and an optical coupler having a light emitting section and a light sensitive section is connected to control said contactless switch, wherein at making, the bidirectively controlled contactless switch first will connect the load, and after a certain period of time, the electromagnetic relay contacts will be energized to connect the load; and at breaking, the electromagnetic relay contacts will first open, whereupon the bidirectively controlled contactless switch will disconnect the load at a zero voltage phase crossing; the optical coupler includes a zero voltage phase crossing detector, wherein after activation or deactivation of the light-emitting section, the zero voltage phase crossing detector will detect a zero voltage phase crossing of the load energy source so that the light-sensitive section activates or deactivates the bidirectively controlled contactless switch at a zero voltage phase crossing of the load energy source, and the primary coil of the electromagnetic relay is connected in series with a transistor, said transistor amplifies the voltage level from a first RC-network, comprising a first resistor and a first capacitor, said first RC-network is connected in parallel to the transistor and the primary coil, with the base of the transistor connected between the resistor and the capacitor, to delay the energizing of said primary coil.
Claim 3
Dependent Claim
21 words
A switching circuit according to claim 1, wherein a second RC-network is connected to delay the de-energizing of the contactless switch.
Claim 4
Dependent Claim
33 words
A switching circuit according to claim 2, wherein said second RC-network has a time constant greater than, or equal to one half of a period of the phase of the load energy source.