Standby power supply

• US 4,956,563 A
• Filed: 11/09/1987
• Issued: 09/11/1990
• Est. Priority Date: 11/09/1987
• Status: Expired due to Fees

• Current Assignee: Wiremold Co (Legrand SA)
• Original Assignee: Perma Power Electronics Incorporated
• Inventors: Schornack, Louis W.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Logan, Sharon D.
• Application Number:
  US07/118,789
• Time in Patent Office: 1,037 Days
• Field of Search: 307/64, 307/66, 307/87
• US Class Current: 307/66
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A battery operated standby inverter power supply uses an electromechanical relay switching network to connect and disconnect line power between input and output terminals. An overcurrent relay pulser rapidly opens the switching system relay contacts upon transition to battery mode, and a breakover diode network accelerates field collapse in the relay coil attendant to reversion of the relay to its normally closed condition attendant to each battery to line transition. A fault detector establishes acceptable line voltage thresholds, the exceeding of either of which triggers operation from line to battery mode. These triggering thresholds are automatically pulled closer together during initial system startup. An overload detector senses the load current in line mode and prevents actuation to battery mode if the load connected to the power supply output exceeds the rated current value of the inverter. A wiring detector prevents initial power-up to line mode in the event that the house wiring has been miswired so as to interchange the house ground and the voltage return lines.

Claims

1. A power supply for providing electrical power to a load in case of power line voltage failure comprising:

input terminal means adapted for connection to electrical power lines;

load terminal means adapted for connection to said load;

battery-operated inverter means for providing electrical power to said load terminal means;

fault detector means responsively coupled to said input terminal means for producing a low-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude below a given valve and for producing a normal-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude above said given value;

control switching means responsively coupled to said fault detector and operable to a line-power state responsively to the presence of said normal-voltage-indicating condition and to a battery-power state responsively to the presence of said low-voltage-indicating condition and including means for transferring electrical power from said input terminal means to said load terminal means and operating said inverter means to an inactive condition in sad line-power state and means for interrupting said transfer and operating said inverter mans to an active condition providing electrical power to said load terminal means in said battery-power state;

disabling means for preventing transition of said control switching means from said line-power state back to said battery-power state for a given period of time after transition of said fault detector means from a low-voltage-indicating condition to a normal-voltage-indicating condition so that transient inrush currents into said load producing a momentary low-voltage condition on said power lines do not cause actuation of said control switching means back to said battery-power state.

2. The power supply of claim 1 wherein said disabling means includes means for actuating said fault detector means to maintain said normal-voltage-indicating condition during said given period of time.

3. The power supply of claim 1 wherein said control switching means includes master switching means operable between a power-off state and a power-on state and including means operable responsively to each operation to said power-off state for establishing a disabling condition disabling said inverter means and said control switching means from providing electrical power to said load terminal means:

means responsive to subsequent operation of said master switching means to said power-on state for removing said disabling condition and means for preventing transition of said control switching means from said line-power state to said battery-power state for a given interval of time upon the first provision of electrical power to said output terminal means.

4. A standby power supply for providing electrical power to a load comprising:

input terminal means adapted for connection to electrical power lines;

load terminal means adapted for connection to said load;

battery-operated inverter means for supplying electrical power to said load terminal means and having a given maximum output current rating;

fault detector means coupled to said input terminal means for producing a low-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude below a given value and for producing a normal-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude above said given value;

control switching means operable to a first state supplying electrical power from said input terminal means to said load terminal means and including means for disabling said inverter means to anon-power-supplying condition to said load terminal means and operable to a second state interrupting said supplying of electrical or from said input terminal means to said load terminal means and including means for actuating said inverter means to a power-supplying condition to said load terminal means, said control switching means further including means responsive to said fault detector means for actuating said control switching means to said second state responsively to the presence of said low-voltage-indicating condition and to said first state responsively to the presence of said normal-voltage-indicating condition;

current sensing means responsive to the current drawn by said load when said control switching system is in said first state for providing an overload-indicating signal condition when the current drawn by said load exceeds said maximum current rating of said inverter means; and

transition-disabling means responsive to said current sensing means for preventing operation of said control switching means from said first to said second state thereof responsively to the presence of said overload-indicating signal condition.

5. The power supply of claim 4 further including alarm means responsive to said power sensing means for producing an alerting alarm to the operator responsively to the presence of said overload-indicating condition.

6. The power supply of claim 4 wherein said inverter means includes an output transformer connected to said load terminal means to supply electrical power thereto, switching drivers for switchingly applying battery voltage to the input of said transformer responsively to excitation voltages applied to said drivers, and oscillator means for supplying said excitation voltages, and said control switching means includes inverter control logic means for disabling said inverter means by disconnecting said oscillator means from said drivers responsively to the presence of said normal-voltage-indicating signal condition.

7. A power supply for providing electrical power to a load in case of power line voltage failure comprising:

input terminal means adapted for connection to electrical power lines;

load terminal means adapted for connection to said load;

battery-operated inverter means for providing electrical power to said load terminals;

fault detector means responsively coupled to said input terminal means for producing a low-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude below a given value and for producing a normal-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude above said given value;

control switching means responsively coupled to said fault detector and operable to a line-power state responsively to the presence of said normal-voltage-indicating condition and to a battery-power state responsively to the presence of said low-voltage-indicating condition and including electromechanical relay means having coil means and contact means operable to a closed condition to transfer electrical power from said input terminal means to said load terminal means in said line-power state and including means for operating said inverter means to an inactive condition in said line-power state and including means for interrupting said transfer by operating said contact means to an open condition in said battery-power state and for operating said inverter means to an active condition providing electrical power to said load terminal means in said battery-power state, said relay means being characterized by a known release time delay after a change of energization state of said coil means before said contact means actuate to said open condition and a known drop-in time delay after a reversal of said energization state until said contact means actuate to said closed condition; and

synchronizing means responsive to the presence of said low-voltage-indicating condition for delaying actuation of said inverter means to said power-supplying condition by an amount slightly greater than said release time delay, and including means responsive to power line voltage waveform sensings and the presence of said normal-voltage sensing condition for reversing the energization state of said coil means at a preset time prior to an axis crossing, said preset time being such as to cause closure of said contact means in the immediate vicinity of said axis crossing and means for operating said inverter means to a non-power-supplying condition immediately prior to such closure.

8. The power supply of claim 7 wherein said contact means are in a normally-closed state with said coil means in a de-energized condition, and said control switching means energizes said coil means during a transition from a line-powered state to a battery-powered state, said coil means being characterized by a given minimum opening current to open said contact means and a given holding current to maintain an open condition thereafter, said switching control means further including pulsing means for providing to said coil means a transient current substantially greater than said minimum opening current and for thereafter providing thereto a maintenance current not substantially greater than said minimum holding current.

9. The power supply of claims 7 or 8 wherein said inverter means includes output transformer means connected to said load terminal means and battery charging means powered by said output transformer means when said control switching means is in said line-powered state.

10. The power supply of claim 7 wherein said coil means includes a plurality of diodes connected across said coil means to shuntingly absorb transient voltages from said coil means during the de-energization thereof and having a reverse breakdown in excess of the d.c. voltage drop across said coil means when energized and a forward voltage drop in excess of that of any one of said diodes, said forward drop being chosen to regulate the rate of field collapse in said coil means to a chosen value.

11. The power supply of claim 10 wherein said plurality of diodes includes s breakover first diode having a given reverse breakdown voltage connected in series with a second diode in a blocking direction with respect thereto, so that the forward drop of said diode means is approximately the reverse breakdown voltage of said first diode and the reverse breakdown voltage of said diode means is approximately the reverse breakdown voltage of said second diode.

12. In a standby power supply for providing electrical power to a load and including input terminal means adapted for connection to electrical power lines, load terminal means adapted for connection to said load, battery-operated inverter means for supplying electrical power to said load terminal means, fault detector means coupled to said input terminal means for producing a low-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude below a given value and for producing a normal-voltage-indicating condition responsively to the presence of a power line voltage having an amplitude above said given value, the improvement comprising:

electromechanical relay means having coil means and contact means for transferring therethrough electrical power from said input terminal means to said load terminal means, said coil means being responsive to the application of a control current therethrough to operate said contact means to a change of state;

control switching means operable to a first state actuating said relay means to transfer said electrical power therethrough and including means for operating said inverter means to a non-power-supplying condition to said load terminal means and operable to a second state actuating said relay means to interrupt said supplying of electrical power from said input terminal means to said load terminal means and including means for actuating said inverter means to a power-supplying condition to said load terminal means, said control switching means further including means responsive to said fault detector means for actuating said control switching means to said second state responsively to the presence of said low-voltage-indicating condition and to said first state responsively to the presence of said normal-voltage-indicating condition; and

diode means comprising a plurality of diodes connected across said coil means to shuntingly absorb transient voltages from said coil means during the de-energization thereof and having a reverse breakdown in excess of the d.c. voltage drop across said coil means when energized and a forward voltage drop in excess of that of any one of said diodes, said forward drop being chosen to regulate the rate of field collapse in said coil means to a chosen value.

13. The power supply of claim 12 wherein said diode means includes a breakover first diode having a given reverse breakdown voltage connected in series with a second diode in a blocking direction with respect thereto, so that the forward drop of said diode means is approximately the reverse breakdown voltage of said first diode means is approximately the reverse breakdown voltage of said second diode.