Contact protection circuit and high voltage relay comprising the same

A contact protection circuit for arc suppression, comprising:

• a main switch for interrupting a flow of current through a load path of an electrical circuit;
• an auxiliary switch;
• a PTC device;
• and
• a current sensitive coil adapted to operate the auxiliary switch;
• wherein the auxiliary switch, the PTC device and the current sensitive coil are connected in a series arrangement, and the series arrangement is connected in parallel to the main switch;
• and
• wherein if the main switch is operated to interrupt the flow of current through the load path while the auxiliary switch is closed, the auxiliary switch is maintained closed by the current sensitive coil during a given time interval after the main switch opens,
• wherein the given time interval depends on a transition of the PTC device from a low resistance state to a high resistance state.

A switching device, comprising:

• a main switching mechanism comprising a main switch for electrically interrupting a flow of current through a load path, the main switching mechanism and the main switch being provided as a main relay comprised of:
• a main coil for operating the main switch via an energizing coil voltage;
• and
• a main coil protective element connected to the terminals of the main coil and adapted to control the decay of magnetic inductance stored in the main coil when the energizing coil voltage is disconnected;
• an auxiliary switching mechanism comprising an auxiliary switch;
• and
• a PTC device connected with the auxiliary switch in a series arrangement, the series arrangement being connected in parallel to the main switch;
• wherein the auxiliary switching mechanism is adapted to maintain the auxiliary switch closed during a given time interval after the main switch is operated to open, the given time interval depending on a transition of the PTC device from a low resistance state to a high resistance state.

A switching device, comprising:

• a main switching mechanism comprising a main switch for electrically interrupting a flow of current through a load path;
• an auxiliary switching mechanism comprising:
• an auxiliary switch;
• a first coil for operating the auxiliary switch via an energizing coil voltage;
• and
• a first coil protective element connected to the terminals of the first coil and adapted to control the decay rate of the magnetic inductance stored in the first coil when the energizing coil voltage is set to zero;
• a PTC device connected with the auxiliary switch in a series arrangement, the series arrangement being connected in parallel to the main switch;
• and
• wherein the auxiliary switching mechanism is adapted to maintain the auxiliary switch closed during a given time interval after the main switch is operated to open, the given time interval depending on a transition of the PTC device from a low resistance state to a high resistance state.