Multiple circuit overload protection device

• US 5,229,908 A
• Filed: 04/24/1991
• Issued: 07/20/1993
• Est. Priority Date: 04/24/1991
• Status: Expired due to Term

• Current Assignee: Nilfisk, Inc. (Japan) (Nilfisk Holding A/S)
• Original Assignee: U.S. Products, Inc.
• Inventors: Gurstein, Russell, Gurstein, Bernard
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): To, E.
• Application Number:
  US07/690,419
• Time in Patent Office: 818 Days
• Field of Search: 361/85, 361/47, 361/76, 307/471, 307/479, 307/511, 307/592, 307/127, 307/130, 307/86, 307/39, 307/34, 307/38, 307/11, 324/521, 324/86, 340/825.7, 340/658, 323/910
• US Class Current: 361/85
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

A sensor connected to two different phases of an electrical wiring system provides positive protection against overloading of any single phase by preventing operation of one circuit load when there is no phase difference between the wiring circuits.

Claims

1. An apparatus for prevention of overloading of a two-wire circuit of a three-wire electrical system comprising in combination:

a first voltage supply line and a second voltage supply line;

a first load and a second load, wherein said first load is connected to said first voltage supply line;

means for sensing when said first and second voltage supply lines are out of phase;

means responsive to said means for sensing for connecting said second load to said second voltage supply line when said first and second supply lines are out of phase; and

a bypass switch means for bypassing said means for connecting said second load to a second voltage supply line, regardless of whether said first and second voltage supply lines are in or out of phase.

2. The apparatus in accordance with claim 1, further comprising means for indicating when said switch means for bypassing is open or closed when said first and second voltage supply lines are out of phase.

3. The apparatus in accordance with claim 1, further comprising means responsive to said means for sensing for supplying a voltage to an indicator when said first and second voltage supply lines are out of phase.

4. The apparatus in accordance with claim 1, further comprising an indicator lamp for signaling the presence of out-of-phase power on said first and second voltage supply lines.

5. The apparatus in accordance with claim 1, further comprising a first exclusive OR gate for comparing the phase of voltages on said first and second voltage supply lines, and providing an output if said voltages are out of phase.

6. The apparatus in accordance with claim 5, further comprising a switch means responsive to said first exclusive OR gate for turning on and off a load connected to one of said first and second voltage supply lines.

7. The apparatus in accordance with claim 5, further comprising a second exclusive OR gate for detecting the presence of a voltage on one of said first and second voltage supply lines,

means responsive to said second exclusive OR gate and to said fist exclusive OR gate for providing an indication that a voltage is present on said second voltage supply line, and that the voltages on said first and second voltage supply lines are out of phase.

8. An apparatus for connecting a second load to a second circuit when said second circuit is out of phase with a first circuit having a first load comprising in combination:

means for sensing the phase of said first and second circuits;

means for automatically connecting said second load to said second circuit when said first and second circuits are out of phase; and

means for bypassing said means for sensing and for connecting said second load when said first and second circuits are in phase or out of phase.

9. The apparatus in accordance with claim 8, further comprising means responsive to said means for sensing, for comparing the phases of said first and second circuits, and means for producing a signal when said first and second circuits are out of phase.

10. The apparatus in accordance with claim 8, further comprising means for indicating when said first and second circuits are out of phase.

11. The apparatus in accordance with claim 8, further comprising means for indicating when said first load and said second load are respectively connected to said first and second circuits having different phases.

12. The apparatus in accordance with claim 8, further comprising means for indicating when said first and second circuits are out of phase and when said load is connected to said second circuit.

13. The apparatus in accordance with claim 8, further comprising manual switch means for preventing automatically connecting said second load to said second circuit when said first and second circuits are out of phase.