CURRENT MONITOR

• US 3,573,782 A
• Filed: 05/23/1968
• Issued: 04/06/1971
• Est. Priority Date: 05/23/1968
• Status: Expired due to Term

• Current Assignee: John E. Williams
• Original Assignee: John E. Williams
• Inventors: Williams, John E.
• Application Number:
  US04/731,588
• Time in Patent Office: 1,048 Days
• US Class Current: 340/664
• CPC Class Codes: F42B 15/36 Means for interconnecting rocket-motor and body section; Multi-stage connectors; Disconnecting means
• CPC Class Codes: F42C 21/00 Checking fuzes; Testing fuzes
• CPC Class Codes: G01R 19/16509 using electromagnetic relays, e.g. reed relay magnetically driven reeds G01R9/06
• CPC Class Codes: H01H 47/001 Functional circuits, e.g. logic, sequencing, interlocking circuits

Abstract

A current monitor is provided for indicating the presence of the short duration current pulses necessary to detonate ordnance devices and simultaneously interrupt the ordnance firing circuit to simulate firing conditions. The current monitor consists of a reed switch magnetically linked to the firing circuit by a low resistance coil in series with the firing circuit. The normally opened reed switch is connected in series with the monitor power source and the control gate of a silicon controlled rectifier. The monitor source of power is also connected in series with a relay and the anode of the silicon controlled rectifier, the relay being adapted, upon activation, to both interrupt the firing circuit and to generate an instrumentation signal indicative of the presence of the required current flow in the firing circuit. In operation a current pulse sufficient to detonate the ordnance device will cause the reed switch to close and trigger the silicon controlled rectifier. When the silicon rectifier is triggered, the current will be permitted to flow through the relay thereby interrupting the firing circuit and producing the instrumentation signal. Since the current is no longer flowing through the firing circuit, the reed switch will open, but this will not interrupt the flow of current through the relay since the silicon controlled rectifier will continue to conduct once it has been triggered. Thus, the relay remains activated and the instrumentation signal is maintained until the circuit is reset.

Claims

1. A current monitor capable of detecting the flow of current of a predetermined level in a circuit to be monitored and capable of interrupting the circuit to be monitored upon the detection of a flow of current of said predetermined level therein, said current monitor comprising:

a. a source of DC power distinct from the source of power in said circuit to be monitored;

b. a latching switch comprising a normally nonconductive element and a trigger element adapted to render said nonconducting element conductive upon application of an electrical signal to said trigger element;

c. a normally open reed switch in series with said source of DC power and the trigger means of said latching switch;

d. a relay connected in series with said source of said DC power and the normally nonconductive element of said latching switch;

e. means for generating an instrumentation signal in response to the flow of current through said relay;

f. coil means for producing a magnetic field adequate to activate said reed switch upon the flow of current of said predetermined level through said coil g. a normally closed switch connected in series with said coil means said switch being operatively connected to said relay whereby said switch will open upon activation of said relay; and

h. means for connecting said coil means and said normally closed switch means in series with said circuit to be monitored;

whereby flow of a predetermined current level through said circuit to be monitored will cause said reed switch to close thereby permitting an electrical signal from said DC power source to be applied to said latching switch rendering said latching switch conductive and permitting the flow of current from said source of DC power through said relay to cause a generation of the instrumentation signal and the interruption of the circuit to be monitored.

2. The current monitor of claim 1 further comprising time delay circuit means operatively connected between said reed switch and the trigger of said latching switch, said time delay circuit means delaying the triggering of the latching switch until said current to be monitored has existed in said circuit for a predetermined period of time whereby the activation of said relay means is delayed.

3. The current monitor of claim 1 further comprising means for detecting the flow of a current in said circuit to be monitored at a second lower predetermined level for a predetermined period of time said means comprising:

a. a second latching switch comprising a normally nonconductive element and a trigger element adapted to render said nonconducting element conductive upon application of an electrical signal to said element;

b. a second normally opened reed switch in series with said source of DC power;

c. second coil means for producing a magnetic field adequate to activate said second reed switch upon the flow of a current of said second predetermined level through said second coil means;

d. time delay circuit means operatively connected between said second reed switch and the trigger of said second latching switch, said time delay means delaying the activation of said trigger means of said second latching switch until said current has existed in said circuit to be monitored at said second lower predetermined level for said predetermined period of time; and

e. current carrying means connecting the normally nonconductive element of said second latching switch to said relay;

whereby flow of current at said first predetermined level will generate an instrumentation signal and cause interruption of said circuit to be monitored by means of said first latching switch and whereby flow of current in said circuit to be monitored at a level equal to or greater than said second lower predetermined level but less than said first predetermined level will cause a generation of an instrumentation signal and interruption of said circuit to be monitored by means of said second latching switch only if said current exists for said predetermined period of time.

4. The current monitor of claim 1 wherein said latching switch comprises a silicon controlled rectifier.

5. The current monitor of claim 2 wherein said latching switch comprises a silicon controlled rectifier.

6. The current monitor of claim 3 wherein said first and second latching switches comprises silicon controlled rectifiers.