Arc detector for electric rod furnace

Claim 2

Apparatus for detecting repetitive arcing in an electric furnace supplied by an electrical direct current source wherein an electrical current surge accompanies each arc event comprising detector means responsive to surges in the direct current flow for producing an arc pulse each time the current change exceeds a predetermined rate, a counter preset for a given count and connected to the detector means to count each arc pulse for producing a counter signal when the counter reaches the said given count, timer means for producing a regular series of reset pulses defining predetermined sample periods, the reset pulses being coupled to the counter to reset the counter at the occurrence of each reset pulse so that the counter is able to reach the given count only when the required number of arc pulses occurs within a single sample period, and output circuitry for producing an output when the counter produces a counter signal.

Claim 3

Apparatus for detecting and stopping repetitive arcing in an electric rod furnace supplied by an electrical direct current source wherein an electrical current surge accompanies each arc event comprising means sensing the direct current flow to the furnace and generating an electrical signal substantially proportional thereto, detector means responsive to surges in the signal for producing an arc pulse each time the signal change exceeds a predetermined rate, a counter preset for a given count and connected to the detector means to count each arc pulse for producing a counter signal when the counter reaches the said given count, timer means for producing a regular series of reset pulses defining predetermined sample periods, the reset pulses being coupled to the counter to reset the counter at the occurrence of each reset pulse so that the counter is able to reach the given count only when the required number of arc pulses occurs within a single sample period, and output circuitry coupled to the current source of turning off the current when the counter produces a counter signal.

Claim 4

Apparatus for detecting and stopping repetitive arcing in an electric rod furnace supplied by an electrical direct current source wherein an electrical current surge accompanies each arc event comprising means sensing the direct current flow to the furnace and generating an electrical signal substantially proportional thereto, detector means responsive to surges in the signal for producing an arc pulse each time the signal change exceeds a predetermined rate, a counter preset for a given count and connected to the detector means to count each arc pulse for producing a counter signal when the counter reaches the said given count, timer means for producing a regular series of reset pulses defining predetermined sample periods, the reset pulses being coupled to the counter to reset the counter at the occurrence of each reset pulse so that the counter is able to reach the given count only when the required number of arc pulses occurs within a single sample period, and output circuitry coupled to the current source of turning off the current when the counter produces a counter signal.

Claim 5

Apparatus for detecting and stopping repetitive arcing in an electric rod furnace supplied by an electrical direct current source wherein an electrical current surge accompanies each arc event comprising detector means responsive to surges in the direct current flow for producing an arc pulse each time the current change exceeds a predetermined rate, a counter preset for a given count and connected to the detector means to count each arc pulse for producing a counter signal when the counter reaches the said given count, timer means for producing a regular series of reset pulses defining predetermined sample periods, the reset pulses being coupled to the counter to reset the counter at the occurrence of each reset pulse so that the counter is able to reach the given count only when the required number of arc pulses occurs within a single sample period, and output circuitry including a latch means for producing a continuous output for energizing a relay when the counter produces a counter signal, the relay being coupled to the current source to turn off the current upon relay energization.

Claim 6

Apparatus for detecting and stopping repetitive arcing in an electric rod furnace supplied by an electrical direct current source wherein an electrical current surge accompanies each arc event comprising detector means responsive to surges in the direct current flow for producing an arc pulse each time the current change exceeds a predetermined rate, a counter preset for a given count and connected to the detector means to count each arc pulse for producing a counter signal when the counter reaches the said given count, timer means for producing a regular series of reset pulses defining predetermined sample periods, the reset pulses being coupled to the counter to reset the counter at the occurrence of each reset pulse so that the counter is able to reach the given count only when the required number of arc pulses occurs within a single sample period, and output circuitry including a latch means for producing a continuous output for energizing a relay when the counter produces a counter signal, the relay being coupled to the current source to turn off the current upon relay energization.